Nepean Power AUDIT CHECK SHEET

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AS 4871.2012 Part 1

AS 4871.2012 Part 1

2.1 2.1.1 Risk Management

Risk management techniques shall be employed. This includes identification, assessment, control, implementation and validation, covering the full life cycle including the design and use of the equipment. Techniques may include hazard analysis, risk assessment, failure mode and effect analysis, and functional safety analysis. Control measures shall be implemented as appropriate to account for all foreseeable hazards. Reference should be made to AS 4024 (series), AS/NZS 4240 series , AS/NZS ISO 31000, AS 60204.1, AS 61508 series and AS 62061. The end user/operator should provide adequate information relating to the mine or quarry’s Environment, electrical systems and protection schemes to the equipment designer. NOTE: Information to be supplied by the purchaser is listed in Appendix A. Where personnel may be in proximity of any moving machinery or plant during normal mining activities, consideration should be given to appropriate technologies such as proximity detection of persons to provide a means of ensuring power is removed if personnel are in an area not deemed to be a safe working zone, i.e. personnel entering an area of danger and not required to be there as part of normal operation of the equipment.NOTES: 1 For information on integrated control systems refer to Appendix B. 2 The use of programmable electronic systems introduces an additional possibility of failure or defeat if access to safety related software is not properly designed and monitored.

2.1.2 Supply System

The supply system associated with power to mining and quarrying equipment and machines covered by this Standard shall have earth-fault current limitation, i.e. an IT system. NOTE: AS 3007 provides detail of the IT system and other systems. Except for battery powered mobile machines, electrical equipment shall be suitable for operating on a power supply that incorporates earth-fault current limitation. Consideration should be given to voltage and frequency regulation, when designing equipment.

2.1.3 System Faults

Consideration shall be given to the fault levels of electrical circuits to ensure the electrical equipment and cabling are selected and installed to match the system design fault level. Any protection study undertaken should consider the affects of minimum and maximum possible fault levels.

2.1.4 Equipment Section

For further information, selection of equipment is covered by AS 60204.1. Electrical components and devices shall — (a) be suitable for their intended use; (b) conform to relevant standards where such exist; and (c) be applied in accordance with the supplier’s instructions. The electrical equipment should be suitable for the switching and interrupting capacity relevant to rated voltages and short-circuit currents.

2.1.5 Temperature Rating

To protect against the risk of burn injury, the maximum external surface temperature of Accessible parts of electrical equipment enclosures intended to be touched shall not exceed 70˚C under normal operating conditions. Refer to AS 60204.1 for use of appropriate warning signs. Additional precautions may be necessary to prevent the risk of injury to persons. Refer to Section 3 for hazardous areas. The temperature rating of all selected electrical/electronic equipment to be installed within the enclosure shall be suitable for use at the operational temperature within the enclosure, at maximum load. In accessing service temperature, the ambient temperature at the mine or quarry shall be considered. NOTE: See Appendix A, Paragraph A1.

2.1.6 Assembly

The equipment shall be assembled so as to guard against mechanical and electrical failure under normal conditions of use, and to maintain the degree of protection (IP rating) required by component parts. The equipment shall be arranged to be accessible for mounting, wiring, maintenance and replacement. Operating devices such as handles, push buttons and levers, shall be accessible and designed and arranged to minimize the risk of inadvertent operation or damage. Components should be installed and wired in such a manner that proper functioning is not impaired by interactions, including heat, arcs, vibration and fields of energy under normal and rated-through-fault conditions.

2.1.7 Construction

Consideration, during the design stage, shall be given to the arduous handling and transportation conditions to which the equipment is to be subjected. Suitably rated lifting and towing points, skid bases, fork lift facilities and the like should be included in the design.

2.1.8 Arc Blast Protection

Consideration shall be made for the prevention of arc blast injury. This shall include the positioning of operating handles, explosion vents, integrity and guarding of windows. Consideration should be given to the use of remote switching. NOTE: Further information is given in IEEE 1584 and NFPA-70E.

2.2 Enclosure Enquires

2.2.1 General

The design of all enclosures used in both safe and hazardous areas shall consider the following parameters: (a) Component layout. (b) Shock loading and vibration levels. (c) Operator safety by means of— (i) doors, fixed panels and partitions to prevent contact with live conductors and exposure to arcing products; (ii) an enclosure rated to contain or control the effects of the prospective fault energy; (iii) vents located in a position to direct any arc products away from the operator; and (iv) pressure relief to atmosphere for any abnormal pressures developed in safe area equipment directed away from and with due regard to the safety of the operator. The location and size shall be adequate for the nominated fault rating and to Limit internal pressures to safe limits for the equipment. (d) Operating environment.

2.2.2 Ingress Protection (IP)

Enclosures shall - (a) have a minimum degree of protection IP 55 in accordance with AS 60529; or (b) be located in a controlled environment that eliminates exposure to water spray. NOTE: In selecting an appropriate IP rating, consideration should be given to the intended Operating environment including physical location and level of exposure to water and dust. Refer to Appendix A for guidance on supplying information. This requirement applies to non-hazardous and hazardous areas.

2.2.3 Internal Segregation

Where possible, components and wiring of high voltage, low voltage and extra-low voltage installed in a common enclosure, should be segregated. Where compartmental segregation is not possible then techniques including insulation, earth barrier, restraint, creepage and clearance between different voltages should be employed.

2.2.4 Withdraw-able and plug-in equipment

Enclosures with withdraw-able and plug in equipment shall be constructed so the equipment modules cannot be dislodged from their position during normal operation. Withdrawable and plug-in equipment containing power circuits shall not operate unless fully engaged.

2.2.5 Unused openings and threaded entries

Unused openings and threaded entries shall be closed or plugged so the degree of protection (see Clause 2.2.2) or the explosion-protection integrity of the enclosure or both is maintained. Precautions shall be taken to prevent release during normal service conditions.

2.2.6.1 General

The requirement to fit interlocking shall be determined by risk management. The following factors shall be considered when determining if and where required: (a) Exposure to live conductors. (b) Accessibility to the enclosure. (c) Special fasteners and tools. (d) Live line indication. Equipment shall be designed to minimize the risk of inadvertent exposure to live electricity. Interlocking shall not be relied upon as a means of isolation to gain access to enclosures supplied with greater than extra-low voltage. The system shall be designed to prevent the easy or inadvertent removal of access covers on enclosures when the power is switched on, and in addition shall prevent restoration of power to the enclosure while the access cover is open. Access covers shall be interlocked with a switching device, or padlocked or bolted with warning signs so it is not possible to inadvertently open or remove the cover with the power on. Interlocking systems shall have a category of protection consistent with AS 4024.1501 or safety integrity levels consistent with AS/NZS 62061. If the enclosure to which the cover provides access contains live conductors above ELV that either— (i) can be contacted by persons; or (ii) are not protected by acceptable insulation material of thickness and grade appropriate to the voltage, to prevent inadvertent contact by a person, then covers and access covers shall be marked in accordance with Clause 5.4.

2.2.6.2 Interlocking

Every interlocking system that dies not have a rigid mechanism link between the isolating device and the latch on the enclosure being protected shall be designed using functional safety principles. Refer Clause 2.1.1 Acceptable interlocking methods are as follows: (a) Mechanical interlocking - where mechanical system of interlocking may be used in conjunction with an isolating switch, the following may apply: (i) The isolating switch, assembly shall be arranged so that, when mounted in its enclosure it is only possible for the actual position of the isolating switch contacts to correspond to the external position indicator forming part of the operating handle (ii) A method of captive interlocking will be acceptable as mechanical interlocking between the isolating switch and enclosures(s). (b) Electrical interlocking - Undervoltage releases, providing the function of 'no volt, no close' is the preferred form of the electrical release for electrical interlocking. Where a shunt trip device is the only form of tripping, a safety appraisal in Accordance with Clause 2.1.1 shall be undertaken. Appropriate facilities to monitor or test the functionality shall be provided as determined in the safety appraisal. Only totally enclosed interlock switches of robust construction shall be used. Switch terminals shall be shrouded. Any electrical interlocking switch circuit shall be ELV. (c) Electromechanical interlocking — Where electromechanical interlocking is used, it shall comply with the relevant parts of the requirements in Items (a) and (b), to achieve an equivalent level of safety. NOTE: It is recognized that methods of interlocking to prevent inadvertent access to HV enclosures may not be possible due to the use of HV supply cables not having pilot cores (e.g. PILSWA cable). Consideration should be given to alternate control measures such as an audio/visual device inside the enclosure to warn if the cover is removed with the enclosure energized.

2.2.6.3 Electrical interlocking of restrained plugs

Where restrained plugs and receptacles above ELV are used and there is likelihood of a person coming in contact with live pins, provision shall be incorporated to automatically disconnect electricity when the plug is removed, and to prevent automatic restoration of electricity on the insertion of the plug into its receptacle. The interlocking shall not be relied upon as a means of isolation.

2.2.7 Protection against direct and indirect contact

Design considerations shall include protection from electric shock caused by direct or indirect contact with electricity. NOTE: See Appendix C. Also refer to AS/NZS 3000, AS 60204.1 and AS 60204.11 for guidance.

2.3 Component Requirements

2.3.1 Creepage and clearance

It is recommended that the characteristics of the component and the insulation of the associated circuit be examined to assess the need for protection against transient over voltages that may occur during closure or interruption of the circuit. Consideration should be given in the design to the selection and construction of electrical components to prevent the occurrence of an arcing fault. The following provisions apply: (a) All insulation other than battery cells and boxes shall have a minimum comparative tracking index (CTI) of 400 in accordance with AS/NZS 60112 or a suitable BIL or impulse level. Refer to AS 1824.1. (b) Insulation techniques, creepage and clearance dimensions shall be appropriate for each system voltage and operating condition. NOTES: 1. Appendix D provides recommendations for minimum creepage and clearance distances in air and in clean environments. In abnormally dusty, moist or corrosive environments greater distances should be considered. 2. In IT systems the phase-to-earth creepage and clearances distances should match the phase-to-phase distances. On a three-phase impedance earthed (IT) system, the two Unfaulted phases will rise from phase-to-earth voltage to phase-to-phase voltage. (c) Impulse testing may be applied as an alternative to establish suitable creepage and Clearances distances. Refer to Clause 4.5 and Appendix H, Paragraph H1.5. The manufacturer's recommendations shall be followed regarding special measures to prevent a gradual reduction in the insulation values due to unfavourable ambient conditions (e.g. deposits of conductive dust and chemical attack). (d) Components shall be adequately rated. (e) Interphase barriers shall be either earthed metal or insulated types. (f) Cable terminations shall meet the general electrical requirements and, where relevant, the specific standards relating to explosion-protection techniques.

2.3.2 Switching Devices

2.3.2.1 General

Switching devices, as detailed below, shall comply with a relevant standard appropriate to the application. Reference should be made to manufacturers published performance data to ensure the Protection provided is appropriate to the application, including maximum and minimum fault currents and maximum clearance time. Consideration shall be given to the mechanical endurance requirements of switching devices, the electrical switching capacity (including short-circuit) and low power factor when subject to frequent operation. All switching devices shall be mounted, keeping spaces, clearances and orientation in accordance with the manufacturer’s instructions and in a manner provides optimum accessibility for maintenance purposes. Where the switching device is required for the purpose of isolation for the safety of personnel carrying out maintenance or repair, provision shall be made for locking the switching device in the off position. Where the switching device is required to be operated by the general workforce at the mine or quarry, the device should not be capable of being locked in the on position. A safety Assessment shall be conducted where a device is capable of being locked in the on position. See also Clause 2.3.2.2(c). Where required, switching devices may have provision for the following features associated with the means of isolation: (a) Test position. (b) Earth position. (c) Phase reversal position.

2.3.2.2 Isolating switches (disconnectors)

Isolating switches shall be mounted for ‘dead front’ operation. Isolating switches shall be of the following types: (a) Fault make, fault break. (b) Fault make, load break. (c) Off load make, off load break. Where used, this type shall be equipped with and interlocking device that removes the load before the device is operated and has a suitable category or safety integrity level relevant to the risk. Refer to Clause 2.1.1. Isolating switches shall be capable of being locked into the open position.

2.3.2.3 Circuit Breakers

The mounting of the circuit breaker shall provide for ‘dead front’ operation. Where a trip-free mechanism forms part of the main power supply switching device, it shall not be possible for the moving contacts to close onto the fixed contacts while the trip mechanism is held in the tripped position, either by manual means or under the influence of a de-energized under voltage release. The circuit breaker tripping device shall trip the circuit breaker operating mechanism by one or more of the following methods: (a) Direct electromechanical operation. (b) Operation of an undervoltage release. (c) Operation of a shunt release. Where a shunt release is provided as the only means to trip the circuit breaker, the following requirements shall apply: (i) The shunt release system shall be subject to a safety assessment in accordance with Clause 2.1.1. Where a shunt release is used as the only form of tripping it shall have two energy sources available for normal operation. One source may be a stored energy type that is capable of operating the shunt release at least once when the normal power supply is removed. Appropriate facilities to monitor or test the functionality shall be Provided as determined in the safety assessment. (ii) Where access to the stored energy device is required, tripping of the circuit breaker shall occur and access to the stored energy device shall not be possible until the stored energy device has discharged to a safe level.

2.3.2.4 Contactors

Electrically operated contactors, where used, shall comply with the relevant standards. All contactors shall be mounted— (a) so the contactor cannot close inadvertently; (b) in accordance with the manufacturer’s recommendations, including adequate arc ventilation for air break contactors; and (c) so as to provide optimum accessibility for maintenance purposes. Where more than one contactor is required to maintain an operation sequence and reversing or speed changing and failure of a contactor may create a risk due to incorrect movement or damage to equipment then suitable interlocking shall be employed.

2.3.3 Transformers

2.3.3.1 General

Transformers can be dry, gas filled (pressurized) or contain an insulating liquid as a coolant.

2.3.3.2 Power Transformers

Power transformers shall comply with AS 60076.1 or an equivalent and applicable standard. NOTE: Consideration should be given to the duty cycle to which the power transformer will be subjected. The core of all power transformers and any associated non-current-carrying metal shall be effectively connected to the enclosure earth by an earthing conductor.

2.3.3.3 Control Transformers

Control Transformers Control transformers shall comply with the following requirements: (a) Be of the dry type construction. (b) Have separate input and output windings electrically isolated from each other. (c) Have an earthed shield placed between the primary and secondary windings.

2.3.3.4 Current and instrument transformers

Current and instrument transformers used for measurement or protection shall be selected relative to the requirements of the protection or instrumentation equipment duty. Current transformers shall comply with AS 60044.1. Instrument transformers shall comply with AS 60044.2.

2.3.4 Measuring Instruments

Where measuring instruments are fitted, they shall comply with the following requirements: (a) Measuring instruments shall be adequately protected from impact damage. (b) Measuring instruments shall not be connected into any protective circuit such that the measuring instrument may impair the operation of the protective circuit.

2.3.5 Terminals

The method of termination should be suitable for and maintain contact pressure for conductors rated to the proposed current and prospective fault level. Terminals intended for the connection of external conductors should be so arranged that they are readily accessible. The method of termination shall be such that conductors of dimensions compatible with the rated current values may be readily connected and that contact pressures are permanently maintained without detriment to the conductors. NOTE: The majority of mining cables have flexible multi-stranded conductors and consideration should be given to the different cross sections and manufacturers recommendations when selecting the dimensions of the terminals and crimp lugs to which they may be connected. Where connecting screws are employed, tightening of the screws shall be possible without excessive turning or displacement of the terminal and displacement of the conductor. The effectiveness of a terminal shall not depend upon pressure on insulating material which may shrink or deform in service.

2.3.6 Cable Connections

Facilities shall be provided for the connection of cable(s) so as not to compromise the enclosure integrity regarding the degree of protection (see Clause 2.2.2) or explosion- protection characteristics.

2.3.7 Motors

All motors shall comply with the relevant standards. For all types of motors, maximum surface temperature is an important consideration. It is recommended that all motors be fitted with internal temperature detection. It is recommended that motor enclosures have a minimum IP rating of IP 55 in accordance with AS 60529 unless in a controlled environment. Motor connection operating temperatures should be considered when selecting motor cables.

2.3.8 Variable Speed Drives

Variable speed drive (VSD) systems shall comply with this Standard. In particular, Section 4 tests shall apply having regard to the full range of operating conditions, including speed range, voltage and supply frequency. VSD technology represents a range of operating conditions that may be different to the normal electrical conditions expected, such as with motor drives running at relatively constant speed and on 50 hertz sinusoidal supply. These different operating conditions may create increased levels or new types of risk not covered by the traditional protection measures covered elsewhere in this Standard. With the rapidly changing range of technologies, switching devices and operating conditions of use, it is not possible to specify in this Standard all possible risks and control measures. Manufacturers and users of these technologies should consider the differences that may create additional or new hazards, e.g. changing operating power supply frequency, high frequency switching harmonics, power segregation and common mode voltages between incoming and outgoing VSD circuits. Before installing any VSD, operators should review the manufacturer’s recommendations for the safe use of this equipment to make sure the device is used within its safe limits. NOTE: Appendix E provides a list of possible risks and guidance notes. This list is not exhaustive, but is a reference list of the typical range of possible risks that need to be considered with any VSD system when complying with this Standard. Undesirable outcomes may exist where an inappropriate combination is used or where one component is not compatible with the application.

2.3.9 Resistors

Where resistors are used, they shall be designed so that any operating condition shall not cause the enclosure surface temperature to rise above that specified in Clause 2.1.5.

2.3.10 Electronic Based Systems

2.3.10.1 General

Where any electronic/programmable electronic based system (E/PE system) is employed and relied upon for safety critical applications on any plant or equipment, these shall be subjected to a safety assessment in accordance with AS 62061 or AS 61508 series. Overall system functional safety is of prime importance. It is recommended that management plans be implemented at all phases of the life cycle of the equipment. This will include definitions of responsibility, risk assessment, safety integrity levels, commissioning, maintenance, and revision control. The complexity of these plans should be appropriate for the E/PE system. NOTE: AS 62061 provides typical guidelines for the design and management of safety related E/PE systems.

2.3.10.2 Hardware

Electronic-based systems shall be manufactured in accordance with a recognized Standard, appropriate to the application. All printed circuit boards shall be adequately protected from the environment. The maximum internal temperature of the enclosure shall be no greater than the temperature rating of any component. The power supply to these units should have suitable noise immunity and performance for the intended application. Where microprocessors or other electronic equipment are used they shall be installed in an enclosure that provides a minimum degree of ingress protection suitable for the applicationand design of the equipment. NOTE: Environmental conditions or the type of machine may call for the flameproof enclosures to have a degree of protection that complies with either the first or second numeral or both, according to the assessed condition of operation. All electronic apparatus shall be designed to satisfy the maximum internal temperature that may occur in the enclosure in which it is installed. (This applies to microprocessors, barriers, electronic devices and protection/relays.) In accessing service temperature, the Ambient temperature at the mine or quarry shall be considered. NOTE: See Appendix A, Paragraph A1.

2.3.10.3 Isolation of data and communication lines

Where data communications devices are used they should be arranged to minimize the coupling of hazardous voltages onto data communications lines. In particular, data modems that connect or couple to power cables should be suitably rated for the application and type tested to withstand the expected voltage range. This should include consideration of any coupling to any energized circuits at remote locations and possibly different voltages to ensure, these circuits are effectively isolated. NOTE: For hazardous areas, this requirement applies to all non-IS applications.

2.3.10.4 Software

Software shall be considered an integral part of any safety related E/PE system. An appropriate software quality management plan should be adopted for any E/PE system or piece of equipment. The plan shall cover the complete life cycle and include responsibilities, risk management, specification and safety integrity levels, commissioning, change control, and documentation. NOTE: AS 61508.3 provides typical guidelines for software management.

2.3.11 EMC Immunity and Emission

The equipment shall not generate electromagnetic disturbances above levels that areappropriate for its intended operating environment. In addition, the equipment shall have a level of immunity to electromagnetic disturbances so it can function in its intended environment. The equipment shall be installed in accordance with manufacturer's recommendations. NOTES: 1 Measures to limit the generation of electromagnetic disturbances and enhance the immunity are provided in AS 60204.1. 2 Refer to AS/NZS 61000 series for guidance. Spectrum management for radio controlled equipment shall be considered. Refer to AS/NZS 4240 (series).

2.4.1 Conductor Isulation

Adequate steps should be taken in the selection of conductor insulation and the types of terminations and materials employed to prevent insulation deterioration which, due to partial discharge and surface tracking, could result in an arcing fault. Insulating materials should comply with relevant standards.

2.4.2 Protective Earthing Covers

The minimum cross-sectional area of any earthing conductor shall comply with AS/NZS 3000 or AS 3007 or as specified for cables in Clause 2.4.7. This may be as detailed in Table 5.1 of AS/NZS 3000 for copper earthing conductor sizes or by calculation.

2.4.3 Neutral Earthing Conductors

The cross-sectional area of the neutral earthing conductor between the transformer neutral terminal and the earth-fault limitation device shall be one of the following: (a) Fifty percent of the cross-sectional area of the main power conductor, up to and including 70 mm2. (b) Thirty-three percent of the cross-sectional area of conductors above 70 mm2, with a minimum cross-sectional area of 35 mm2. (c) Rated by calculation for the full unrestricted phase to earth-fault current and clearing time (I2t). NOTE: Cables need not exceed 95 mm2 when provided with additional mechanical protection and should be kept as short as practical. The conductor connecting the earth-fault limiting device to earth shall be rated at twice the fault limited current or have a minimum cross-sectional area of 4 mm2, whichever is the greater. The conductors shall be mechanically protected.

2.4.4 Power Conductors

When selecting the conductor insulation type and size, the cyclic (RMS) loading and the fault capacity for the time taken to interrupt the fault shall be taken into account. NOTES: 1 Refer to AS/NZS 3008, Parts 1.1 and 1.2, for calculating the cyclic loading and fault capacity. 2 Consideration should be given to conductors for any through feed/extension supply.

2.4.5 Control, protection and auxiliary conductors

Where there is a reduction of cross-sectional area of conductors connecting the power source to an auxiliary circuit protective device, the conductors shall be double insulated and as short as possible.

2.4.6 Internal Wiring

Internal wiring in the enclosure shall be restrained to prevent mechanical damage and the fouling of moving components. Through-conductors should maintain the same phase rotation on any extension supply. All wiring and conductor ends shall be identified with a durable system of marking. All wiring shall be selected, installed and protected in accordance with the particular environment, including exposure to high temperatures.

2.4.7 Cables

Cables used for power supply and distribution in any mine or quarry for equipment covered In this Standard shall be suitable for the intended application, duty and environment, Including exposure to high temperatures. Cables shall comply with one of the following as appropriate for the application: (a) For below ground reeling and trailing cable applications, power cables shall comply with AS/NZS 1802. (b) For below ground machine cable applications, cables shall comply with AS/NZS 1972 Or AS/NZS 1802. Refer also to Section 3.9 for hazardous areas. (c) For above ground reeling and trailing cable applications, power cables shall comply with AS/NZS 2802. NOTE: This Standard does not exclude the use of polymeric cables in other parts of the mining operation.

2.5 Connection Facilities For Earthing And Equipotential Bonding Conductors

2.5.1 General

A connection facility for the connection of an earthing conductor shall be provided inside any electrical enclosure. Metal gland(s) and cable armouring (if any) shall be connected or bonded to earth. Electrical apparatus, operating above ELV, with a metallic enclosure shall have an additional external connection facility for an equipotential bonding conductor. This external connection facility shall be electrically continuous with the internal earthing connection facility. NOTE: The expression ‘electrically continuous’ does not necessarily involve the use of a conductor. The connection facility shall be suitable for the effective connection of at least one conductor with a cross-sectional area as required by Clause 2.4.2 and shall be protected against corrosion. The connection facility shall be designed so that the conductors are secured against loosening and twisting and maintain contact pressure. The main incoming earth shall be electrically bonded to the equipment frame.

2.5.2 Cables containing only analog/or digital signals

For screened cable containing only analog and/or digital control signals, the screen should be earthed, at one end only, usually at the non-field end.

2.5.3 Circuits requiring earthing

2.5.3.1 General

Where it is necessary to provide for earthing of circuits, an earth switch shall be provided on the load side of the isolating switch. Where the earth switch does not earth external circuits, an additional earthing facility shall be provided to discharge the external circuits. The earth switch should be fault-make rated equivalent to the fault rating of the enclosure with its contacts. The earth switch shall be interlocked with the circuit isolating switch. Where a fault-make rating is not practicable, the interlock shall be rated in accordance with a functional safety analysis. Circuit earthing procedures shall be clearly identified.

2.5.3.2 Visibility of contacts

The position of the disconnector and earth switch blades shall be visible from outside the enclosure housing the live parts or be indicated by means of a mechanical linkage directly coupled to the switch contacts that can only indicate open when all contacts are open and indicate closed when all contacts are closed. Live line indication shall be provided.

2.5.3.3 Live Line Indication

Live line indication shall be provided. The location of the indication shall be determined by safety assessment and may be on the line side, load side or both.

2.6 Protection Requirements

2.6.1 General

For electrical protection of circuits and equipment, automatic circuit opening devices of adequate rating shall be used. The range of recommended settings of each device shall be specified for overload and short circuit currents consistent with the normal operating loads, maximum fault current of the electrical equipment, and current rating and impedance of cables. The resetting of any electrical fault protection device shall not result in automatic restarting.

2.6.2 Earth Protection Scheme

2.6.2.1 General

The electrical earthing protection strategy shall be such that the level of step and touchpotential and time exposed is limited to acceptable levels when the equipment is under fault conditions. The acceptable levels of prospective touch voltage and operating time shall be obtained from Figure 1. NOTE: Refer to Appendix C for guidance. To ensure touch potentials caused by electrical faults on equipment are managed to acceptable levels, the complete electrical system should be designed and assessed and a protection scheme implemented in accordance with design and assessment. The protection system design shall consider the total clearance time of protection and switching devices. The protection scheme limits the risk of— (a) an ignition of gas or dust; (b) high resistance earth return paths; (c) explosion or fire initiated by electrical arcing; and (d) exposure to electrical contact with live parts. NOTE: The relevant regulatory authority may specify additional requirements and setting values. This Clause does not apply to battery-powered machines or alternator systems associated with diesel powered machines. Refer to AS/NZS 4871.5 and AS/NZS 4871.6 for requirements for these systems. The protection scheme shall employ each of the following (see Clause 2.6.2.2 to 2.6.2.6) as required.

2.6.2.2 Earth-fault Current Limitation

Where earth-fault limitation is required under Clause 2.6.2.1, a device complying with the performance and construction requirements of AS/NZS 2081 shall limit the earth-fault current. The ratio of earth-fault current to earth leakage protection trip should be at least 10. For systems where capacitive charging currents may cause spurious tripping, a lower ratioof at least 5 may be used subject to a detailed system assessment, including charge current and time, component reliability and operating tolerance. For reliable operation, the earth- Fault limitation should be as low as possible and the tripping ratio should be as high as possible. NOTE: A system assessment should take into account the functional safety of the protection systems.

2.6.2.3 Earth-continuity Protection

Earth-continuity protection devices complying with the performance and construction requirements of AS/NZS 2081 shall be used to protect any circuit employing restrained receptacles or supplying mobile or portable equipment through trailing or reeling cables. In the event the earth impedance exceeds the value as nominated in the mine or quarry’s earth-protection scheme, the device shall cause switching device controlling the power to the supply cable to— (a) open, if it is in the closed position; and (b) not to close if it is in the open position. Each earth-continuity monitoring circuit shall have a test facility to verify the operation of the protection system. See Clause 3.4.3 for special requirements for hazardous zones.

2.6.2.4 Earth Leakage Protection

On external circuits where the supply is above ELV, earth-leakage protection devices shall be used to detect earth-leakage currents and shall comply with the design and construction requirements of AS/NZS 2081. Facilities to prevent resetting by unauthorized persons shall be provided. Each earth leakage protection circuit shall have a test facility to verify the operation of the protection system. The test leakage current should not exceed 1.2 times the earth-protection trip setting.

2.6.2.5 Earth-fault Lockout Protection

Where power is supplied to a mobile or portable machine by a trailing or reeling cable, protection shall be provided to prevent the introduction of electrical power if an earth-fault is detected on the circuit to be energized. Lockout earth-fault protection devices shall comply with the requirements of AS/NZS 2081. See Clause 3.4.5 for special requirements for hazardous zones.

2.6.2.6 Neutral-connection Current Limitation System Integrity Protection

Where an earth-fault current limitation device is used, a facility shall be provided to test the state of the earth-fault current limitation circuit. This may be a current limited phase to ground test for testing of earth leakage or a neutral monitoring device.Where a neutral monitoring device is used, it shall comply with the performance and construction requirements of AS/NZS 2081. NOTE: The purpose is to ensure the earth-fault current limitation circuit remains effective. An open circuit failure would allow a single earth-fault to go undetected, and a second earth-fault may then create unsafe touch voltages.

2.6.3 Protection Devices

2.6.3.1 General

General In addition to earth-protection requirements in Clause 2.6.2, the requirements for protection devices in following Clauses 2.6.3.2 to 2.6.3.8 shall apply. The selection of protection devices shall be based on sound electrical protection principles and be provided for the safe operation of the electrical equipment and outgoing circuits, including the protection of persons and the operating environment. Protection settings shall be in accordance with the mine’s electrical protection scheme. Protection devices shall comply with the relevant standard.

2.6.3.2 Emergency Stop Devices and Associated Circuitry

Emergency stop devices and associated circuitry The requirement for emergency stop devices shall be determined by a risk management process. This should consider the integration of individual machines within a system. Emergency stop devices and associated circuitry shall stop all processes or movements that may become hazardous irrespective of the mode of control. Resetting of the emergency stop shall not cause an unplanned or automatic restart. Emergency stop circuits shall be considered a safety function and shall be subject to a functional safety analysis. Control/machine stop devices shall not be used as an emergency stop device. The device shall be of the stop lockoff (latching-in) manual reset type unless allowed otherwise by the risk management process and shall cause the electrical equipment to stop all functions irrespective of the mode of control.

2.6.3.3 Short Circuit Protection

Short-circuit protection Short-circuit protection shall be provided to protect in the event of a short-circuit occurring in any part of the circuit being protected. Short-circuit protection may be incorporated in or external to the electrical equipment. Facilities to prevent resetting by unauthorized persons shall be provided for circuits that supply reeling, trailing or feeder cables. For other circuits, facilities to prevent resetting by Unauthorized persons should be provided where possible. These facilities may be a part of the short-circuit detection device or a part of a separate device that will prevent restoration of power to the faulted circuit while providing indication of the trip.

2.6.3.4 Overload Protection

Overload protection shall have inverse time characteristics appropriate to the load or circuit being protected. Service factor of the protective device shall be considered when determining trip settings.

2.6.3.5 Undervoltage Protection

Where undervoltage protection is fitted, the undervoltage release device shall open the switching device when the voltage across the terminals of the release device falls below a predetermined value.

2.6.3.6 Loss of Vacumm/Frozen Contact Protection

Where a switching device is used for the control of restrained outlets, and elsewhere where determined by the risk management process, an upstream switching device shall be fitted with a shunt and/or undervoltage release to remove power from the faulted switching device. Where loss of vacuum/frozen contact protection is required, the device shall operate under the following conditions: (a) The switching device failing to open when required. e.g. welded contacts. (b) The loss of the insulating medium of the switching device. The protection shall prevent reclosure of the circuit under the above conditions. Facilities shall be provided to prevent resetting by unauthorized persons. Loss of vacuum/frozen contact protection devices shall comply with the requirements of AS/NZS 2081.

2.6.3.7 Under/Over Pressure Protection

Equipment that is dependent upon the maintenance of a relatively constant pressure within its enclosure shall be fitted with a pressure sensing device to automatically cut off the power supply to the incoming switching device when the pressure reaches a predetermined value.

2.3.6.8 Over Temperature Protection

Where fitted, an overtemperature device shall automatically cut off the power supply to the protected device when the temperature reaches a predetermined value.

2.6.4 Transformer Protection

The primary winding of all transformers shall be protected by a suitably rated fault-break device in each supply line.

2.6.5 Motor Protection

Each motor shall be protected by devices that detect overload and/or short-circuit. The overload device shall have an inverse time characteristic. Temperature sensing devices may be built into the motor to initiate a control-circuit trip when a predetermined temperature is exceeded and may be arranged for automatic reset. NOTE: Temperature and other sensing devices should not be connected into intrinsically safe circuits where there is a possibility of a breakthrough of mains voltage without further protection.

2.6.6 Control, Protection or Auxiliary Circuits

Where control, protection or auxiliary circuits are connected across the power circuit, they shall be protected by a suitable over-current protection device located as close as possible to the power circuit connection point (see Clause 2.4.5). Where the control supply is earthed via the centre tap of a transformer, operating coils shall not hold in at a voltage that exists between one leg and the earth point. NOTE: This may require the addition of further protection such as 30 mA earth-leakage protection or insulation monitoring. Where the control supply is earthed at one leg of a transformer, operating coils shall have one side directly connected to the earthed leg via a dedicated return conductor. Extra-low voltage a.c. and d.c. circuits may need to be referenced to earth, to prevent inadvertent operation of equipment. NOTE: This may not apply to IS circuits, where the conditions of certification must be followed.

2.7 Remote Control

For remote control of mobile mining machinery, refer to AS/NZS 4240 series. For remote operation of equipment or plant, such as a circuit-breaker operated by a pendant or a pump float control, the safety of the control shall be taken into account and shall be rated in accordance with a functional safety analysis.

2.8 Proximity Detection

A generic approach is needed to identify hazards relevant to each application where personnel may be in proximity of any moving machinery or plant during normal mining activities. Appropriate technologies should be considered such as proximity detection of persons to provide a means of ensuring power is removed if personnel are in an area not deemed to be a safe working zone, i.e. personnel entering an area of danger and not required to be there as part of normal operation of the equipment. Refer to AS/NZS 4240 Series for information.

2.9 Thermography

Thermography may be considered as a means of preventative maintenance for identifying hot joints in high current applications. Consideration shall be given to potential hazards associated with installation of thermopraphic viewing windows. These may include switchgear manufacturer’s validation of type tests for switchgear enclosures, operator access level (front, rear, lateral, etc.), venting direction of explosion vents, and material of viewing windows if used in underground coal mines.

Section 3: Hazardous Area Requirements

3.1 Scope

This section sets out additional requirements for electrical equipment located in hazardous areas.

3.2 Explosion Protection

All electrical equipment and circuits shall comply with the AS/NZS 2381 series or the AS/NZS 60079 series. Not withstanding any regulatory requirements, designated hazardous areas in underground coal mines shall be regarded as gas group I. Hazardous areas for other applications shall be as determined in AS/NZS 60079.10.1. NOTE: Equipment certified to the AS 2380 series may be deemed to comply with this Clause.

3.3 Aluminium Or Light Metal Alloys Parts

Any item, structure or plant used in gas group I hazardous areas shall not be made of alloys of aluminium, magnesium, titanium and zirconium in which the total content of these metals exceeds 15% by mass and in which the content of magnesium, titanium and zirconium together exceeds 7.5% by mass, where exposed. NOTES: 1 This is to avoid the potential of an incendive spark. 2 Special arrangements for transport should be considered for replacement of any internal electrical components such as heat exchangers, containing aluminium or light alloy.

3.4 Interlocking

3.4.1 General

The requirement to fit electric interlocking shall be determined in accordance with Clause 2.2.6.1, with due consideration for the additional risk of inadvertent ignition of gas in the hazardous zone. Where electrical interlocking is deemed to be not required, a warning label shall be permanently fixed to any enclosure (See Clause 5.4), stating the following: DANGER: ISOLATE ELSEWHERE BEFORE REMOVING COVER NOTE: The purpose of this interlocking is to prevent a non-intrinsically safe energy source being present when the enclosure is in a non-explosion protected state.

3.4.2 Electrical Interlocking

Any circuitry used for electrical interlocking shall be intrinsically safe while the access cover is open. Only totally enclosed interlock switches of robust construction shall be used. Switch terminals shall be shrouded. Consideration should be given to the prevention of defeating of the switch. Adjacent to each interlock switch shall be a warning label (See Clause 5.4) stating the following: WARNING: SAFETY INTERLOCK—DO NOT OPERATE

3.4.3 Pilot Protection Restrained Receptacles

In addition to the requirements of Clause 2.6.2.3, the circuit shall be intrinsically safe in Accordance with Clause 3.4.5. Refer also Clause 3.11.1. This feature shall ensure the power is removed prior to the power connections being separated (shorter pilot pin interrupts the control circuit first). This feature ensures the flameproof integrity of the plug and socket is maintained while the plug is energized and prevents inadvertent contact with live parts.

3.4.4 Earth-fault Lockout

Earth-fault lockout circuits used in a hazardous zone shall be intrinsically safe in Accordance with Clause 3.4.5.

3.4.5 Earth Continuity and Earth-fault Lockout Protection in Hazardous Zones

Earth continuity and earth-fault lockout protection in hazardous zones For the applications in Clause 3.4.3 and 3.4.4 it is possible that earth continuity and earth- fault lockout systems used in a hazardous zone may be energized in a cable or machine that Is located in an area outside the area containing the supply outlet and which may contain a high level of methane. These systems should be certified to Ex ‘ia’ standards. Where a mine is able to demonstrate that it is not possible for these circumstances to existat their mine, then Ex ‘ib’ certification may apply. A suitable warning label (See Clause 5.4) shall be fitted adjacent to outlets. A typical warning label is as follows: WARNING: Ex ‘ib’ INTERLOCKS. NOT TO BE USED FOR SUPPLY TO CIRCUITS INSIDE A HAZARDOUS ZONE WHEN AN ELEVATED LEVEL OF GAS IS DETECTED.

3.5 Enclosures

3.5.1 Stored Energy Devices Other than Batteries

Enclosures that contain stored energy devices other than batteries conforming to Clause 3.7 or components that may have a surface temperature above the temperature class of the electrical apparatus and may be opened faster than the time necessary to allow the devices to discharge or the components to cool shall comply to the requirements of AS/NZS 60079.0. The enclosure shall be marked with the following warning: AFTER DE-ENERGIZING, DELAY Y MINUTES BEFORE OPENING Y being the value in minutes of the delay required. NOTE: Consideration needs to be given to the risk of electric shock and open arcing in the design of this type of system.

3.5.2 Explosion-protected Enclosures

Explosion-protected enclosures Explosion-protected enclosures shall comply with AS 60079 series and shall be certified for the relevant gas group. See Clause 3.2. For flameproof enclosures Ex ‘d’ special attention shall be given to the following aspects: (a) Lubricants Only lubricants that have been tested and verified by the manufacturer to Show that they will not cause a flame transmission shall be used on flanges, spindles and push button operators. Some lubricants have extremely low flashpoints and during an internal explosion they could transmit flame to the outside atmosphere. Lubricants, if applied, shall be of a type that does not harden because of aging, does not contain an evaporating solvent and does not cause corrosion of joint surfaces. (Refer to AS/NZS 60079.1) (b) Fasteners Fasteners used for joints on flameproof enclosures shall not be used for any other purpose. (c) Sealing Where conductors are extended through a common wall between two flameproof enclosures or from a flameproof enclosure to external atmosphere, they shall be sealed in accordance with the enclosure certification. Where multicore or data cables, including fibre optic, are used they shall be sealed with a certified barrier gland or be verified by test for non-transmission of flame. This requirement is not applicable to cables complying with AS/NZS 1972 or AS/NZS 1802. NOTE: Cables complying with AS/NZS 1972 type 9 require verification by test in accordance with AS/NZS 1972.

3.5.3 High Energy Arcing Faults

High energy arcing faults The design of flameproof enclosures should take into account high energy faults that can be detrimental to the integrity of flameproof enclosures. NOTE: See Appendix F for additional information on flameproof enclosures.

3.5.4 Temperature Rating

To protect against fire caused by heating of coal dust, the maximum external surface Temperature of accessible electrical equipment enclosures shall not exceed 150˚C under all Conditions of operation including overloads and faults. Additional precautions may be necessary to prevent the risk of injury to persons. Refer to Clause 2.1.5 and Appendix H.

3.6 Motors

All motors shall be fitted with overtemperature protection devices.

3.7 Batteries

Batteries and energy devices used for memory backup and real time clock batteries used in hazardous areas that are not certified as explosion protected and any associated circuits (except batteries covered by AS/NZS 4871.5 and AS/NZS 4871.6) shall be assessed by an IEC Ex recognized test laboratory to one of the following: (a) Be Ex ‘ia’ or Ex ‘ma’ Ex ‘s’ (zone 0) when the mains supply is removed from the enclosure. (b) Conform to AS/NZS 60079.11 ‘simple apparatus’ requirements. (c) Pass a conformity assessment undertaken in accordance with AS/NZS 60079.14. (d) Be housed in explosion protected enclosures meeting the requirements of EPL Ma as documented in AS/NZS 60079.14. NOTES: 1 Unless demonstrated otherwise it should be assumed all programmable logic controllers and like devices reliant on programming or memory include a battery. 2 The requirements of this Standard may be read in conjunction with, but do not take precedence over, regulations of a regulatory authority that may apply in a specific area.

3.8 Cable Hose

Where protective cable hose is used it shall be flame resistant and anti-static in accordance with AS 2660. Consideration should be given to the identification of hoses and to differentiate between electrical and other applications, e.g. hydraulics.

3.9 Machine Cables

3.9.1 General

Cables should be selected for their suitability to the electrical, mechanical and physical environment. This shall include operating temperatures, chemical exposure, mechanical damage exposure and flexibility.

3.9.2 Machine Power Cables

Machine power cables rated in excess of 20 A a.c. shall be symmetrical and comply with AS/NZS 1972 or AS/NZS 1802.

3.9.3 Machine Control Cables and Extra-low Voltage Power Cables

Machine control cables and extra-low voltage power cables Machine control cables and extra-low voltage power cables shall comply with AS/NZS 1972 or AS/NZS 1802. Type 1 machine cables complying with AS/NZS 1972 shall be protected by flame resistant cable hose where not mechanically protected.

3.9.4 Intrinsically Safe Data or Fibre Optic Cables

Where intrinsically safe data and fibre optic cables are not installed or bundled with power/control cables and are run clear of fire hazard areas and clear of grease or oil areas, the sheath need not be flame resistant.

3.9.5 Fibre Optic Cable and Light Source

Refer to AS/NZS 60079.28 for guidance on protection of systems using optical equipment and transmission systems using optical radiation.

Intrinsically Safe Cables

Intrinsically safe cables shall be in accordance with the relevant sections of AS/NZS 60079.11 and AS/NZS 60079.14.

Intrinsically Safe Cable Parameters

Intrinsically safe cable parameters Cables forming part of a system concept certification shall comply with the conditions of certification. For cables used with entity concept certified components, the following important characteristics need to be assessed, to determine maximum cable lengths, for compliance to the component certification: (a) Resistance per unit length. (b) Capacitance per unit length. (c) Inductance per unit length or L/R ratio. Intrinsically safe circuits shall comply with AS/NZS 60079.14. They may be run in the same multicore cable. Consideration shall be given to the following: (i) Faults between circuits. (ii) Protection against mechanical damage. (iii) The cable being adequately secured. (iv) Each circuit occupying adjacent cores.

3.9.8 Non-intrinsically Safe Data and Communication Cable

Non-intrinsically safe data and communication cables shall comply with AS/NZS 1972 or AS/NZS 1802 and shall be assessed for the system energy levels and appropriate protection methods adopted as determined by the risk management process. NOTE: Type 9 cable to AS/NZS 1972 is one type of cable suitable for these applications.

3.9.9 Light Alloy Screening

Light alloy screening is acceptable provided the cable is sheathed and protected against damage.

3.10 Intrinsically Safe Plugs and Sockets

Plugs and sockets used for the connection/disconnection of intrinsic safety circuits shall comply with the requirements of AS/NZS 60079.0 and AS/NZS 60079.11 in respect of the following: (a) Facilities for connection of external circuits. (b) Insulation. (c) Creepage and clearance. The plug or socket assembly shall carry a minimum IP 54 rating, in accordance with AS 60529. The in-line plug or socket shall incorporate a cable clamping/restraining facility. The cable clamping/restraining facility shall— (i) be sized to the cable, to maintain the IP rating; and (ii) be installed in such a manner that tension on the cable is not transmitted to the electrical connections. Electrical continuity of screening, where applicable, shall be maintained through plug and socket connections.

3.11 Intrinsically Safe Conductors

3.11.1 General

Plugs and sockets used for the connection/disconnection of intrinsic safety circuits shall comply with the requirements of AS/NZS 60079.0 and AS/NZS 60079.11 in respect of the following: (a) Facilities for connection of external circuits. (b) Insulation. (c) Creepage and clearance. The plug or socket assembly shall carry a minimum IP 54 rating, in accordance with AS 60529. The in-line plug or socket shall incorporate a cable clamping/restraining facility. The cable clamping/restraining facility shall— (i) be sized to the cable, to maintain the IP rating; and (ii) be installed in such a manner that tension on the cable is not transmitted to the electrical connections. Electrical continuity of screening, where applicable, shall be maintained through plug and socket connections. Any external cabling and components connected to these circuits shall be explosion Protected for hazardous areas. Where the pilot circuit can extend outside the explosion-protected compartment housing the main isolating device, the pilot circuit shall be isolated with the main isolating device or other means employed to ensure the explosion-protected properties are maintained. NOTE: Pilot circuits may be subject to system voltage under fault conditions.

3.11.2 Earthing of Intrinsically Safe Circuits

Earthing of intrinsically safe circuits Any connections to earth shall be made in accordance with the relevant certification documentation. Not all intrinsically safe circuits need to be earthed. Normally earthing is performed at one point only, usually in the non-hazardous area. Where earth connections are necessary to preserve the integrity of an intrinsically safe system (e.g. a diode safety barrier earth, a transformer screen earth, a barrier relay frame earth) such connections shall be made to a high integrity earth in such a way that the impedance from the point of connection to the main power system earth point is less than 1 Ω. A low impedance earth may be achieved by connection to an earth bar. The conductor used for the connection shall be equivalent to a copper conductor of 4 mm2 minimum cross-sectional area. NOTES: 1 The sole purpose of this earthing is to protect the circuit in the hazardous area in the event of invasion in the safe area portion of the circuit by mains voltage, by providing a secure safe return path to the origin of the invading mains voltage. A poorly conductive joint in structural metal may then give rise to arcing or sparking or high temperatures, sufficient to ignite an explosive atmosphere. Additionally, it would then be possible for earth-fault currents originating elsewhere to invade the intrinsically safe circuit and cause problems. 2 AS/NZS 60079.14 provides additional earthing requirements for intrinsically safe applications.

Section 4 : Tests

4.1 General

The tests to verify the characteristics of an assembly include— (a) type tests; and (b) routine tests. Tests shall be performed where required, to verify compliance for electrical equipment covered in this standard and the other 5 parts of the AS/NZS 4871 series.

4.2 Type Tests

4.2.1 General

Type tests are intended to verify compliance with the requirements laid down in this Standard for a given type of assembly. Type tests will be carried out on a sample of such an assembly or on such parts of assemblies manufactured to the same or a similar design. These tests shall be carried out by the manufacturer or supplier. Type tests shall include the following where required in accordance with Appendix H, Paragraph H1: (a) Verification of temperature-rise limits. (b) Verification of the short-circuit withstand strength. (c) Verification of the effectiveness of the protective earth circuit. (d) Verification of clearances and creepage distances. These tests may be carried out in any order and/or on different samples of the same type. If modifications are made to the components of the assembly, new type tests shall be carried out only if such modifications are likely to adversely affect the results of these tests.

4.2.2 Certificates of Type Tests

Type test certificates shall be made available to demonstrate compliance with this standard and other relevant standards, together with detailed particulars of the equipment tested.

4.2.3 Exemption for Re-Test

Re-test of the electrical equipment is not required if it can be established that any alteration in design will not adversely affect the type test performance.

4.3 Routine Tests

Routine tests are intended to detect faults in materials and workmanship. They shall be out on every new assembly after it has been assembled or on each transport unit. Another routine test at the place of installation is not required. Equipment that is assembled from standardized components outside the works of the manufacturer of these components, by the exclusive use of parts and accessories specified or supplied by the manufacturer of the components, shall be routine-tested. Routine tests shall include the following where required in accordance with Appendix H, Paragraph H2: (a) Verification of construction in accordance with type tests. (b) Inspection of the assembly including inspection of wiring and, if necessary, electrical and mechanical operation test. (c) Dielectric and insulation test. (d) Checking of protective earth measures and of the electrical continuity of the protective earth circuit. (e) Partial discharge in accordance with Clause 4.5. These tests may be carried out in any order.

4.4 Testing of Devices And Self-Contained Components Incorporated in the Assembly

Type tests or routine tests are not required on devices and self-contained components incorporated in the assembly when they have been supplied with copies of the test documentation and installed in accordance with the instructions of the manufacturer.

4.5 High Voltage Tests

Partial discharge testing should be undertaken on all equipment operating above 3.3 KV after final assembly of new or rebuilt plant. This is to assist in the identification of defects in both materials and workmanship, and to establish baseline characteristics (signature readings) of the plant for future reference. Additional testing of components and assemblies should be considered, as determined by risk management for all the possible equipment applications (see also Clause 2.3.1). The risk management process should consider factors such as exposure to lightning impulse, network switching surges and longer term deterioration due to partial discharges. For further information refer to Appendix H, Paragraph H1.5 for lightning impulse testing and Paragraph H2.5 for partial discharge testing.

Section 5: Marking and Labelling

5.1 Equipment Marking

This Section sets out requirements and guidance on good practice in labelling of equipment. It shall apply when purchasing, repairing or overhauling equipment. All external labels should be of brass or stainless steel and the marking thereon should be inscribed by etching, engraving or stamping. Labels shall be located in a prominent location. Labels shall be securely attached. Design of labelling should comply with AS 1319 or appropriate International standards.

5.2 Component Marking

All components mounted internally or externally on enclosures should be identified by labels.

5.3 Wiring Marking

All wires associated with power, control, protection and auxiliary circuits should be identified with non-metallic durable numbers. The requirements for the marking of the terminals for the external earthing conductors shall be to AS/NZS 3100. Marking of terminals for other than external earthing conductors should be as follows: (a) Mains supplied equipment: (i) Line terminals ...................................................................................................L1 — L2 — L3. (ii) Earth terminals .............................................E or earth or the international earth symbol. (iii) Outgoing terminals ...............................................................A — B — C (see AS 60076.1). (iv) Colour code The following colour code should be used to indicate terminals: (A) L1 or A ............................................................................................................................Red. (B) L2 or B .........................................................................................................................White. (C) L3 or C ...........................................................................................................................Blue. (D) E..............................................................................................................Green and Yellow. Identification of the conductors of main and auxiliary circuits should be to the requirements of AS 2067. (b) Battery power equipment: (i) Battery output terminals .............................................................................................. +,−. (ii) Earth terminal ....................................E or the international earth symbol (Clause 2.5.1). (iii) Outgoing terminals to motors: Armature................................................................................................A1, A2 or equivalent. (iv) Colour code: (A) Battery mains cabling: +............................................................................................................................................Red. −..........................................................................................................................................Black. (B) Other cabling: Colour code may be considered and where used defined in documentation.

5.4 Warning Labels

Reflective danger and warning labels shall be provided as required and determined by risk management. Labels shall comply with AS 1319 and be permanently fixed in the appropriate location. Typical labels include the following: (a) A warning label shall be prominently displayed adjacent to each interlock switch with wording as follows: WARNING: SAFETY INTERLOCK—DO NOT OPERATE (b) On any cover or door the removal or opening of which exposes live conductors: DANGER XXXX VOLTS. (Highest voltage within the enclosure) DANGER: ISOLATE ELSEWHERE BEFORE REMOVING COVER (c) In close proximity to the incoming and, where fitted, the through-bolted cable coupling adaptor or other connecting device: WARNING: THIS..............IS NOT CONTROLLED BY THIS SWITCH (d) In proximity to all high voltage cable coupling adaptors: WARNING: PRIMARY SIDE CABLE ADAPTORS ARE NOT ISOLATED BY OPENING THIS PRIMARY SIDE CIRCUIT DISCONNECTOR (e) In proximity to any off-load tap changing device: DANGER: OFF-LOAD TAP CHANGER—DO NOT ALTER SETTING WHEN ENERGIZED (f) Multiple power sources: WARNING: MULTIPLE POWER SUPPLIES WITHIN THIS ENCLOSURE. ISOLATE AT ……………….. BEFORE OPENING COVER

5.5 Rating Plate

A rating plate indicating operating ratings of the equipment shall be fitted. This should include the following: (a) Manufacturer. (b) Serial number. (c) Plant number. (d) Volts. (e) Fault capacity. (f) Load ratings. (g) Connected load (where applicable). (h) Total mass of the assembly.

Section 6: Documentation

6.1 Safety File

A safety file shall be provided with any plant and maintained to provide a record of Information about the safety of the plant over the full life cycle. NOTE: Guidance on documentation is given in Appendix G.

6.2 Technical Maintenance and Operational Manuals

Technical manuals shall be included in the safety file to provide information of the correct Operation, maintenance and any limits of safe use of the plant over the full life cycle. These shall include any manuals required under any ANZEx and IECEx certification scheme for explosion-protected certified equipment.
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AS 4871.2010 Part 2

Section 2: Common Requirements

2.1 General

2.1.1

This Standard specifies additional requirements to those in AS/NZS 4871.1.

2.2 Electrical Equipment

2.2.1 Enclosures

Enclosures shall comprise single or multiple compartments, each fitted with suitable covers or access covers, and should incorporate facilities for lifting and transport.

2.2.2 Coupling of Enclosures

Where enclosures are required to be coupled together, the coupling arrangement shall prevent, in normal use, undue strain being placed on any busbars, flanges or interconnecting cable coupling devices.

2.3 Means for Isolation

A means shall be provided to isolate all circuits above extra-low voltage (ELV), except as set out in Clause 3.5.2. All isolators shall be externally operated and fitted with lockout facilities. The Switched position and function of all isolators shall be clearly labelled. The isolating device shall be located in a seperate compartment, together with any control devices necessary for the operation of the isolating device. Auxiliary circuits that are required to remain energized while the main power is isolated, such as lighting and power sources, shall be provided with a means of isolation.

Section 3: Ancillary Plant

3.1 General

This Section covers belt starters, fan starters, splicing equipment, and welders.

3.2 Electrical Protection Systems for Auxiliary Fans

3.2.1 General Requirements for Auxiliary Fans

The following electrical protection shall be provided as a minimum on auxiliary ventilation fans: (a) Thermal overload protection shall be provided on the electric motor of the fan. (b) All bearing temperatures shall be monitored and shall have alarm and trip facilities incorporated into the fan control systems. The trip facilities shall remove power from the fan motor. Set points for the trip facility shall be determined by the fan designer or a properly conducted engineering review. The trip indication from the bearing temperatures shall be latched and access to the reset facilities restricted. (c) Motor winding temperatures shall be monitored and shall remove power from the fan motor in the event of an overtemperature of the windings. This shall be suitable for the class of insulation that is to be used in the motor. (d) Radial and axial vibration protection shall monitor all bearings that support the fan Impellor. (e) Anti-windmilling protection shall be provided and interlocked with the fan control panel to ensure no generated residual voltage is present before access is permitted into the fan control panel. NOTE: Facilities should be provided for locking rotating parts prior to any access. (f) Where the fan control panel may not be readily accessible due to site location, remote stop and start facilities that enable starting and stopping of the fan from a safe location shall be provided. (g) An emergency stop facility that is readily accessible from both sides of the auxiliary fan and removes power from the fan supply cables shall be provided. (h) A phase rotation interlocking facility shall be provided in the fan control circuit to prevent the starting of the fan should the phase rotation of the supply be reversed. (i) An hour run meter shall be provided to monitor the actual run time of the fan.

3.2.2 Additional Requirements for Fans used with Explosive Gases

Access to the fan start facilities shall be restricted. Provision shall be made for the fitment of gas monitoring system suitable for the intended environment. Where an explosive gas monitoring system is provided the system shall have the following features: (a) The trip mechanism shall isolate the power supply to the fan. (b) A lockout mechanism shall be fitted that will prevent the restoration of power to a fan until the trip mechanism is reset. (c) There shall be a visual indication of the gas trip. (d) Where air flow is reduced, such as by venturi bypass, the system shall detect any dangerous concentration of gas in the main air flow within an appropriate time as determined by the risk management process. Electric motors shall not be exposed to gases drawn through the vent ducting. Facilities shall be provided for the interlocking of the fan operation with power supplies that enter all areas that are dependent on the fan operating to maintain a safe environment. Facilities shall be provided to detect any restriction of air flow such as vent tube collapse or restriction. This interlocking shall be rated in accordance with a functional safe analysis.

3.3 Conveyor Starters

3.3.1 General Requirements for Conveyor Starters

General requirements for conveyor starters The following requirements are in addition to those contained within AS 1755. Controllers for conveyor systems shall be fitted with the following; (a) The starter design shall incorporate a single point of isolation, i.e. Main isolator. This main isolator shall- (i) comply with AS/NZS 4871.1; and (ii) be located in its own compartment. (b) All field control devices shall be supplied at voltages not exceeding ELV. (c) The risk management process shall consider the incorporation of vibration and temperature monitoring of each drive motor assembly, drive pulley and other major turning pulleys on the conveyor. (d) Where mechanical braking facilities are provided on a conveyor, these shall be monitored to ensure the brakes are released while the drive motors are energised. (e) Brakes that are used to decelerate a conveyor shall be monitored for over- temperature. Consideration of a means of isolation for individual conveyor drive or auxiliary motors should be addressed, during the risk management process. The risk management process should consider the level of inter-tripping between multiple drive motors of the conveyor in the case a fault occur on any drive motor on that conveyor.

3.3.2 Conveyors for use in Hazardous Areas

All electrical sections of the conveyor that are located within a hazardous area shall be certified to the conveyor explosion protection Standard.

3.4 Belt Splicing Equipment

3.4.1 Splicing Equipment Shall Comply with all General Requirements of AS/NZS 4871.1

Splicing equipment shall comply with all general requirements of AS/NZS 4871.1. Equipment used on site for the purposes of forming hot vulcanized spliced joints in conveyor belting shall conform to the following minimum standards: (a) The splicing equipment shall have an earth leakage circuit breaker having an earth leakage trip value not greater then 30mA for protection of any hand held electrical equipment used in conjunction with the splicing equipment. (b) The splicing control box shall contain circuitry that ensures the platens have an effective earth connection at all times. (A form of pilot circuit will be regarded as complying with this requirement.) (c) The resetting device for the short circuit and earth leakage protection shall be capable of being locked to prevent unauthorised resetting. (d) The plug connecting the platen cable shall be secured with a retention device to ensure the plug cannot inadvertently come free from the platen.

3.5 Welding Equipment

3.5.1 General

Welding equipment shall be in accordance with the following: (a) Welding power sourced shall comply with AS 60974.1, AS 60974.6, AS60079.11, and AS/NZS 3100. (b) All welding machines shall be suitable for use with Category C environment as defined in AS 1674.2. This requirement need not apply if a fully documented assessment of the work environment has been undertaken and implemented in accordance with AS 1674.2.

3.5.2 Isolation

For welding machines a means of isolation as specified in Clause 2.3 is not required if the welding machine is supplied by a switched plug socket.

Section 4: Distribution Control Boxes

4.1 General

This Section specifies additional requirements to those in AS/NZS 4871.1.

4.2 Construction

Distribution control boxes (DCBs) shall be of robust construction suitable for relocation and shall be designed to facilitate inspection and maintenance. The equipment shall be of good quality workmanship, based on sound engineering principles and suitable for its intended use.

4.3 Enclosures

Enclosures shall comprise single or multiple individual compartments, each fitted with suitable covers or access covers.

4.4 Means for Isolation

The incoming supply from the isolation compartment to single or multiple compartments, other than intrinsically safe circuits, shall be fitted with a switching device, lockable in the "off" position, in each active line to isolate all sourced of supply to the main or multiple compartment. The switching device(s) together with any ancillary equipment essential for the safe operation of the device, such as potential transformers, control relays, voltmeters and indication devices, shall be housed in the isolator compartment. An externally operated switching device, lockable in the "off" position, shall be provided for each auxiliary circuit, such as lighting and power sources, that is required to remain energized while the main power is isolated, provided such apparatus and cabling associated with the auxiliary circuits are not housed in the same compartment(s) as equipment isolated by the main switching device. The isolation compartment cover shall be interlocked and suitably labelled in accordance with AS/NZS 4871.1, Clauses 2.2.5 and 3.1.4.

4.5 Protection

Outlets at DCBs should be provided with the following protection devices complying with AS/NZS 4871.1: (a) Loss of vacuum/frozen contact protection. (b) Short-circuit. (c) Overload. (d) Earth leakage. (e) Earth continuity. (f) Earth-fault lockout.

4.6 Positioning of Outlets

Consideration should be given to locating incoming outlets on the opposite side to switched outgoing circuits. NOTE: It is recommended that in addition to the colouring required in AS/NZS 1300, the switch outlets be painted with a band of colour to distinguish between incoming, through feeds and switched outgoing circuits, e.g. Yellow for switched outgoing circuits.

4.7. Lighting

Provision of area lighting should be considered to improve the visibility of labels, indicators, instructions and outlets.

4.8 Labelling

In addition to requirements in AS/NZS 4871.1, labelling shall include the following: (a) Operational instructions. (b) Identification of outlets. A durable label shall be placed adjacent to and in an unambiguous location for each of the following cable connection facilities: (i) For the supply connection - DANGER - SUPPLY CONNECTION. THIS CONNECTION IS NOT ISOLATED BY THIS CIRCUIT BREAKER (ii) For the extension supply - DANGER - EXTENSION SUPPLY CONNECTION. THIS CONNECTION IS NOT ISOLATED BY THIS CIRCUIT BREAKER (c) Identification of switching devices. Labelling shall be clear and unambiguous. All switched positions of the switching device shall be clearly indicated externally.

Section 5: High Voltage Section Isolators

5.1 General

Section isolators are used to provide isolation and earthing of an individual section of the electrical distribution system of the mine. The position of the isolating switch and earth switch blades shall be visible from outside the enclosure housing the live parts or to be indicated by means of a mechanical linkage directly coupled to the switch contacts that can only indicate open when all contacts are open and indicate closed when all contacts are closed. Live line indication shall be provided. NOTE: Section isolators may also incorporate a circuit-breaker providing functionality as per the requirements of Section 6.

5.2 Interlocking

Mechanical interlocking shall be provided between the earth switch and the isolator to prevent - (a) accidental closure of earth switch to an energized circuit; and (b) accidental application of power to a closed earth switch.

5.3 Rating of Switching Devices

The isolator (disconnector) shall have a load and short-time withstand current rating at least equal to the nominated design rating. The isolator shall have a fault-make load-break rating. The earth switch on the load side of the isolator shall - (a) be a fault-make rated earth switch; or (b) where a fault-make rated earth switch is not practicable then an interlock shall be fitted to open the isolator before the earth switch contacts close. The interlock shall be rated in accordance with a functional safety analysis.

5.4 Positioning of Outlets

Consideration should be given to locating incoming outlets on the opposite side to a switched outgoing circuits. NOTE: It is recommended that in addition to the colouring required in AS/NZS 1300, the switch outlets be painted with a band of colour to distinguish between incoming and switched outgoing circuits: yellow for switched outgoing circuits, red for supply side circuits.

5.5 Explosion Vents

Explosion vents that allow the free passage of escaping gases and vapours that may be present during an arcing fault shall be provided on all non-explosion protected high voltage isolators. Such explosion vents shall be capable of allowing the pressure created to be dissipated without explosive release of energy that could cause injury to personnel. Explosion vents shall be positioned such that escaping gases are directed away from Personnel.

5.6 Labelling

In addition to requirements in Part 1, labelling shall include the following: (a) Operational instructions. (b) Identification of outlets. A durable label shall be placed adjacent to and in an unambiguous location for each of the following cable connection facilities: (i) For the supply connection - DANGER - HIGH VOLTAGE SUPPLY CONNECTION. THIS CONNECTION IS NOT ISOLATED BY THIS SWITCHING DEVICE. (ii) For the extension supply - DANGER - HIGH VOLTAGE EXTENSION SUPPLY CONNECTION. THIS CONNECTION IS NOT ISOLATED BY THIS SWITCHING DEVICE (iii) For the load side - DANGER - HIGH VOLTAGE LOAD CONNECTION. (c) Identification of switching devices. (d) Labelling shall be clear and unambiguous.

Section 6: Section Circuit Breaker

6.1 General

In addition to providing the functionality of a section isolator, section circuit-breakers provide a means of protection against a range of fault conditions.

6.2 Circuit Breakers

Circuit-breakers may be either fixed or withdrawable type to provide isolation. Where a withdrawable circuit-breaker is used it shall - (a) have a fault-make rated earth switch on the load side of the circuit breaker; or (b) where a fault-make rated earth switch is not practicable, an interlock shall be fitted to open the circuit breaker before the earth switch contacts close. The interlock shall be rated in accordance with the functional safety analysis. Where a fixed type circuit-breaker is used the following requirements apply; (i) It shall be fitted with a load break disconnect switch and fault-make earth switch. (ii) Where a load break rated disconnect switch is not practicable, an interlock shall be fitted to open the circuit breaker before the disconnect switch contact open. Where a fault-make rated earth switch contacts close. The interlocks shall be rated in accordance with a functional safety analysis. (iii) Circuit earthing procedures shall be clearly identified. (iv) Live line indication shall be provided.

6.3 Under-Voltage Mechanisms

Consideration should be given to the use of circuit-breakers fitted with an undervoltage mechanism, to prevent automatic restoration of power. For underground coal mines circuit-breakers shall be fitted with an undervoltage mechanism to prevent automatic restoration of power.

6.4 Rating

The section circuit-breaker assembly shall be adequately rated for the intended application.

6.5 Protection

The following protection shall be provided in compliance with AS/NZS 4871.1: (a) Short-circuit. (b) Overload (c) Earth leakage. A positive means of fault diagnosis shall be provided to identify individual fault trips after loss of power.

6.6 Remote Operation

For remote operation of fixed switchgear the safety of the control shall be taken into account and shall be rated in accordance with a functional safety analysis, e.g. Fixed switchgear may be a circuit-breaker operated by a pendant.
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AS 4871.2010 Part 3 Audit Check Sheet

2.1 General Requirements

Substations shall be of rugged construction and shall be capable of withstanding the arduous conditions of handling to which they may be subjected. They shall comply with the following requirements: (a) Where a liquid-filled transformer or oil-filled switch gear is used in an underground mine, a means of containing the total volume of liquid in case of leakage shall be provided. NOTES: 1. Risk management in accordance with AS/NZS 4871.1 should be applied in regard to the use of oil-filled transformers or oil-filled switch gear in an underground mine. 2. A base in the form of a tray capable of containing 110% of the total volume of liquid in the substation and designed to facilitate easy cleaning would fulfil this requirement. (b) Substations shall be of robust construction, suitable for relocation and shall be designed to facilitate inspection and maintenance. The equipment shall be of good quality and workmanship, based on sound engineering principles and suitable for its intended use. (c) Transportable substations shall incorporate facilities for lifting, transport and towing. NOTE: This should take into account the need for relocation of transportable substations. (d) Each sub-assembly of the substation shall be securely fixed to a frame in a manner that shall prevent detrimental flexing of the substation. Push-buttons and control operators should be located or suitably guarded to prevent damage.

2.2 Labelling

In addition to requirements in AS/4871.1, labelling shall include the following: (a) Operational instructions. (b) Where a lifting facility of a sub assembly is not capable of being used to lift the complete substation assembly, means shall be provided to warn/prevent them being used after the substation is assembled. (c) Identification of outlets. A durable label shall be placed adjacent to and in an unambiguous location for each of the cable connection facilities, as follows: (i) For the supply connection. DANGER - HIGH VOLTAGE SUPPLY CONNECTION. THIS CONNECTION IS NOT ISOLATED BY THIS CIRCUIT BREAKER. (ii) For the extension supply. DANGER - HIGH VOLTAGE EXTENSION SUPPLY CONNECTION. THIS CONNECTION IS NOT ISOLATED BY THIS CIRCUIT BREAKER. (d) Identification of switching devices. (e) Labelling shall be clear and unambiguous. (f) Outlets shall be coloured to the colouring required in AS/NZS 1300.

2.3 Lighting

Area lighting should be considered to improve the visibility of labels, indicators, instructions and outlets.

2.4 Explosion Vents

Explosion vents that allow the free passage of escaping gases and vapours that may be present during an arcing fault shall be provided on all non-explosion protected high voltage switchgear assemblies. Such explosion vents shall be capable of allowing the pressure created to be dissipated without explosive release of energy that could cause injury to personnel. Explosion vents shall be positioned such that escaping gases are directed away from personnel.

2.5 Primary Switchgear Assembly

2.5.1 General

Circuit-breakers or combination fuse switch (CFS) units shall be provided in conjunction with protection devices to provide a means of protection against a range of fault conditions. An externally operated switching device, lockable in the "off" position shall be provided for auxiliary circuits, such as lighting and power sources. The externally operated switching device shall remain energized while the main power is isolated, provided such apparatus and cabling associated with the auxiliary circuits are not housed in the same compartment(s) as equipment isolated by the main switching device.

2.5.2 Circuit-breaker

Circuit-breakers may be either fixed or withdrawable type to provide isolation. Where a withdrawable circuit-breaker is used it shall - (a) have a fault-make rated earth switch on the load side of the circuit breaker; or (b) where a fault-make related earth switch is not practicable, an interlock shall be fitted to open the circuit breaker before the earth switch contacts close. The interlock shall be rated in accordance with a functional safety analysis. Where a fixed type circuit-breaker is used, it shall- (i) be fitted with a load break disconnect switch and fault-make earth switch; or (ii) where a load break rated disconnect switch is not practicable, an interlock shall be fitted to open the circuit breaker before the disconnect switch contacts open. Where a fault-make rated earth switch is not practicable, an interlock shall be fitted to open the circuit breaker before the earth switch contacts close. The interlocks shall be rated in accordance with a functional safety analysis. NOTE: Consideration should be given to the installation of a load break switch as on the line side of any potential transformers associated with the sub-station, refer to figure A1. Circuit earthing procedures shall be clearly identified. Live line indication shall be provided.

2.5.3 CFS Unit

Where a CFS unit is used it shall have a fault-make earth switch on the load side. The contacts of the earth switch and the disconnect switch shall be visible from the outside of the enclosure. The position of the contacts of the earth switch and the disconnect switch shall be reliably indicated from the outside of the enclosure as specified in AS/NZS 4871.1.

2.5.4 Undervoltage Mechanism

Consideration should be given to the use of circuit-breakers fitted with an undervoltage mechanism, to prevent automatic restoration of power. For underground coal mines circuit-breakers fitted with an undervoltage mechanism to prevent automatic restoration of power.

2.5.5 Rating

The primary switch gear assembly shall be adequately rated for the intended application and at least equal to the transformer full-load rating.

2.5.6 Protection

The following protection shall be provided: (a) Short-circuit. (b) Overload. (c) Secondary side earth leakage. (d) Circuit-breaker loss of gas/vacuum. (e) Transformer over-temperature. (f) Transformer loss of gas, if gas pressurized. (g) Transformer low oil, if oil filled. For short-circuit, earth leakage and loss of gas/vacuum trips, a positive means of fault diagnosis shall be provided to identify individual fault trips after loss of power.

2.5.7 Interlocking

Mechanical interlocking shall be provided between the earth switch and the primary switching device to prevent - (a) accidental closure of earth switch to an energized circuit; and (b) accidental application of power to a closed earth switch.

2.5.8 Positioning of Outlets

All outlets shall be positioned to allow ease of connection or removal of plugs and adequate bending radius of cables.

2.6 Secondary Switchgear Assembly

2.6.1 General

Where by design, circuit interruption of the secondary side of the substation is desired, it shall be fitted with a switching device.

2.6.2 Protection

Outlets at the secondary side should be provided with the following protection devices complying with AS/NZS 4871.1: (a) Failure of a circuit opening device to cause any phase to remain energizes to trip the supply. (b) Short-circuit (c) Overload. (d) Earth leakage. (e) Earth continuity. (f) Earth-fault lockout. (g) Earth-fault current limiting. (h) NER monitoring or test facility. NOTE: Refer to Appendix A for illustration of these devices.

2.6.3 Positioning of Outlets

All outlets shall be positioned to allow - (a) ease of connection or removal of plugs; (b) adequate bending radius of cables; and (c) ready access to outlet controls.

2.7 Transformers

2.7.1 General

The transformers of a substation shall either be of the dry sealed, encapsulated, gas filled (pressurized) type or contain an insulating liquid as the coolant. Power transformers shall comply with AS 2374.1 or equivalent and applicable standard and, unless otherwise specified by the purchaser, its design shall comply with short circuit currents listed in AS/NZS 4871.1 Paragraph H1.2, Appendix H The core and coils of the transformer be securely clamped in order to ensure the whole assembly is sufficiently rigid to withstand and electrical or mechanical stresses, caused by the arduous cyclic duty, which may occur in service and when being transported around the mine.

2.7.2 Lifting and Anchoring of Core

Guides, locating lugs or a combination of both, with adequate fixing bolts shall be mounted inside the tank to register the location of the core. Means for attaching lifting tackle shall be provided on the core frame.

2.7.3 Off-load Tap Changing

A tap changing device, having all positions clearly marked and with provision for locking in all positions, should be provided. Where a hand-wheel operated tap changer is used, it shall be designed to suit the rated temperature and have provision to ensure it cannot be left in any position other than one of the tap positions. Where bolted links are used, they shall be arranged to avoid incorrect connection. The insulating material used shall be of the same temperature class as used for the transformers windings and shall have a comparative tracking index (CTI) of 400 minimum in compliance with AS/NZS 4695.112. Any internal connections including transformer bushing shall be rated to suit the operating temperature.

2.8 Explosion Protected Substations

2.8.1 Construction

Where a substation is constructed as an explosion-protected unit, the transformer shall be of the dry type. The primary, secondary and transformer enclosures shall be certified to the appropriate parts of either AS/NZS 60079 or IEC 60079.

2.8.2 Mixed Explosion Protection Techiniques

Where mixed explosion-protection techniques are used, the interfaced between each component shall not compromise the protection technique of the other.

2.8.3

Transformer enclosures that are constructed as pressurized shall have automatic disconnection of supply from the transformer in the event of the internal pressure rising to 10% above the maximum operating pressure or falling to not less than 1.5kPa above atmospheric pressure.

2.9 Earthing

2.9.1 General

Provision shall be made on each enclosure of the substation for the attachment of an external earthing terminal in accordance with AS/NZS 4871.1.

2.9.2 Earth Terminal

Internal and external earth terminals shall be - (a) readily accessible; and (b) all connected together by means of copper straps or flexible conductors.

2.9.3 Attachment of Earth Strap

Provision shall be made for the attachment of an earth strap - (a) on all outlets on both the primary and secondary enclosures; and (b) between the core and the transformer enclosure.

Section 3: Testing

3.1 General

Tests shall be carried out in accordance with Section 4 of AS/NZS 4871.1 on each of the following sections.

3.2 Test Section

The substation shall be tested either as a complete unit or in individual sections provided each individual section includes terminations that are representative of the adjacent section as follows: (a) Primary section enclosure. (b) Transformer section enclosure. (c) Secondary section enclosure.

3.3 Primary Section

Tests shall be applied as follows: (a) Power supply through connection - The main through busbars shall be tested (b) Power supply T-off to the switching device - From one end of the main through busbars, via the T-off busbars through the switching device, up to and including the Transformer terminals shall be tested. The short circuit is to be applied to the output side of these terminals.

3.4 Secondary Section

Tests shall be applied as follows: (a) Power supply through connection - The secondary busbar and cabling between the Transformer secondary and line terminals of the circuit interrupters shall be tested. (b) Power supply take off - From the secondary busbar through the switching device(s) up to and including the outgoing adaptor or receptacle shall be tested. The short circuit shall be applied at a point beyond the associated plug, and shall be equal to the preferred short-circuit currents given in AS/NZS 4871.1 Table 4.1. The values of rated conditional short-circuit current or rated short-time withstand current shall be determined by such tests and the relationship between peal and r.m.s values shall be as given in AS/NZS 4871.1 Table 4.1.

3.5 Transformer Section

In addition to the test requirements in Section 4 of AS/NZS 4871.1, the transformer test shall comply with AS 2374.5 or AS 60076. Where the transformer manufacturer can substantiate, from other tests and calculations, that the transformer is capable of withstanding the specified through fault levels, type tests on individual transformers may be waived. Through-fault testing that includes the transformer may be undertaken but it is recommended that the transformer manufacturer should be consulted before proceeding with this test.
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Nepean Power AUDIT CHECK SHEET

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PROJECT DETAILS

AS 4871.2012 Part 1

2.1

2.1.1 Risk Management

2.1.2 Supply System

2.1.3 System Faults

2.1.4 Equipment Section

2.1.5 Temperature Rating

2.1.6 Assembly

2.1.7 Construction

2.1.8 Arc Blast Protection

2.2 Enclosure Enquires

2.2.1 General

2.2.2 Ingress Protection (IP)

2.2.3 Internal Segregation

2.2.4 Withdraw-able and plug-in equipment

2.2.5 Unused openings and threaded entries

2.2.6.1 General

2.2.6.2 Interlocking

2.2.6.3 Electrical interlocking of restrained plugs

2.2.7 Protection against direct and indirect contact

2.3 Component Requirements

2.3.1 Creepage and clearance

2.3.2 Switching Devices

2.3.2.1 General

2.3.2.2 Isolating switches (disconnectors)

2.3.2.3 Circuit Breakers

2.3.2.4 Contactors

2.3.3 Transformers

2.3.3.1 General

2.3.3.2 Power Transformers

2.3.3.3 Control Transformers

2.3.3.4 Current and instrument transformers

2.3.4 Measuring Instruments

2.3.5 Terminals

2.3.6 Cable Connections

2.3.7 Motors

2.3.8 Variable Speed Drives

2.3.9 Resistors

2.3.10 Electronic Based Systems

2.3.10.1 General

2.3.10.2 Hardware

2.3.10.3 Isolation of data and communication lines

2.3.10.4 Software

2.3.11 EMC Immunity and Emission

2.4.1 Conductor Isulation

2.4.2 Protective Earthing Covers

2.4.3 Neutral Earthing Conductors

2.4.4 Power Conductors

2.4.5 Control, protection and auxiliary conductors

2.4.6 Internal Wiring

2.4.7 Cables

2.5 Connection Facilities For Earthing And Equipotential Bonding Conductors

2.5.1 General

2.5.2 Cables containing only analog/or digital signals

2.5.3 Circuits requiring earthing

2.5.3.1 General

2.5.3.2 Visibility of contacts

2.5.3.3 Live Line Indication

2.6 Protection Requirements

2.6.1 General

2.6.2 Earth Protection Scheme

2.6.2.1 General

2.6.2.2 Earth-fault Current Limitation

2.6.2.3 Earth-continuity Protection

2.6.2.4 Earth Leakage Protection

2.6.2.5 Earth-fault Lockout Protection

2.6.2.6 Neutral-connection Current Limitation System Integrity Protection

2.6.3 Protection Devices

2.6.3.1 General

2.6.3.2 Emergency Stop Devices and Associated Circuitry

2.6.3.3 Short Circuit Protection

2.6.3.4 Overload Protection

2.6.3.5 Undervoltage Protection

2.6.3.6 Loss of Vacumm/Frozen Contact Protection

2.6.3.7 Under/Over Pressure Protection