Collection of standards in electronic format (PDF) 1. Copyright

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1 Collection of standards in electronic format (PDF) 1. Copyright This standard is available to staff members of companies that have subscribed to the complete collection of SANS standards in accordance with a formal copyright agreement. The document may reside on a CENTRAL FILESERVER or INTRANET SYSTEM only. Unless specific permission has been granted, this document MAY NOT be sent or given to staff members from other companies. Doing so would constitute a VIOLATION of SABS copyright rules. 2. Indemnity Standards South Africa accepts no liability for any damage whatsoever that may result from the use of this material or the information contained therein, irrespective of the cause and quantum thererof. Click on one of the two boxes I agree with the above I do not agree

2 ICS ISBN Any reference to SABS 1885 is deemed to be a reference to this standard (Government Notice No of 8 November 2002) SOUTH AFRICAN NATIONAL STANDARD Metal-clad switchgear for rated a.c. voltages above 1 kv and up to and including 36 kv General requirements and methods of test Published by Standards South Africa 1 dr lategan road groenkloof private bag x191 pretoria 0001 tel: fax: international code Standards South Africa 2004

3 Table of changes Change No. Date Scope Amdt Amended to update referenced standards, and to replace reference to SABS SM 155, SABS IEC 60056, SABS IEC and SABS IEC with reference to SANS 7253, SANS , SANS and SANS , respectively. Abstract Specifies the requirements for factory-assembled, modular design, metal-clad switchgear panels for indoor installation, for rated a.c. voltages above 1 kv and up to and including 36 kv, for use on threephase systems. Is applicable to metal-clad, indoor switchgear panels with single and double busbars. Keywords electrical engineering; high voltage; high-voltage equipment; measuring techniques; specifications; switchgear; testing. Foreword This South African standard was approved by National Committee StanSA SC 67A, Electrical distribution systems and components - High-voltage switchgear, in accordance with procedures of Standards South Africa, in compliance with annex 3 of the WTO/TBT agreement. This standard was originally published as NRS 003, before it was converted to a national standard. This edition cancels and replaces the first edition (SABS 1885:2001). A vertical line in the margin shows where the text has been modified by amendment No. 1. Annexes A, B and C form an integral part of this standard. Annexes D to F are for information only. Introduction This standard was prepared to establish and promote uniform requirements for indoor metal-clad switchgear for a.c. voltages above 1 kv and up to and including 36 kv, and to enable the purchasers to acquire the specified equipment without the need for detailed and extensive contract documents. The Electricity Suppliers Liaison Committee expresses the wish that in the national interest and to optimize the benefits of standardization, all supply authorities adopt the text of SANS 1885 insofar as their particular conditions will permit. Any differences between SANS 1885 and the corresponding supply authority requirements should, as far as possible, be clearly indicated in schedules A and B, which may be compiled using the draft schedules set out in annex F of this standard and should, where appropriate, be submitted for consideration in future revisions of SANS 1885.

4 Contents Abstract Page Keywords Foreword Introduction 1 Scope Normative references Terms, definitions and abbreviated terms Requirements Ratings Switchgear Circuit-breaker panels Switch-disconnector panels Switch-fuse combination panels Power cable termination Battery, battery chargers and d.c. supplies Current transformers Voltage transformers Protection relays Instruments, transducers and metering Luminous indicators Alarm circuits Auxiliary circuitry Accessories Rating plates Labels Protection against corrosion Tests General Type test Routine tests Test after erection on site Tests on painted surfaces Recommended spares Documentation Documentation with enquiry Documentation with tender Documentation with order Documentation on hand-over

5 Contents (concluded) Page Annex A (normative) Rules for application of standard wire numbering Annex B (normative) Internal arc testing Annex C (normative) Insulation co-ordination in air within the switchgear Annex D (informative) Guidelines on determining contents of test "T" packs Annex E (informative) Guide to purchasers on preparing an enquiry Annex F (informative) Model form for schedules A and B Bibliography

6 Metal-clad switchgear for rated a.c. voltages above 1 kv and up to and including 36 kv General requirements and methods of test 1 Scope 1.1 This standard specifies the requirements for factory-assembled, modular design, metal-clad switchgear panels for indoor installation, for rated a.c. voltages above 1 kv and up to and including 36 kv, for use on three-phase systems. 1.2 The panels will in general each include equipment that comprises a mechanical switching device (for example, a fixed circuit-breaker, a withdrawable circuit-breaker, a switch-disconnector, a switchfuse combination or a switch) in combination with associated control, measuring, indicating, alarm, protective and regulating equipment; including interconnections, accessories, enclosures and supporting structure. 1.3 It is not the intention of this standard to exclude alternatives such as existing single-pole switching equipment or new technical developments. These can be catered for in future either by way of an extension of this document or by additional parts. 1.4 This standard is applicable to metal-clad, indoor switchgear panels with single and double busbars. 1.5 Two or more of the individual switchgear panels are intended to be coupled together in various combinations in order to form one continuous switchboard. NOTE The requirements for standardized panels that comprise preferred combinations of equipment, such as circuit-breakers, switch disconnectors, fused disconnectors (with associated fuses), voltage transformers, relays,, etc., are specified in NRS The switchgear is intended to be used under the following normal conditions of indoor use: a) ambient air temperature: 5 C to 40 C; b) altitude: not exceeding m; c) ambient air: not significantly polluted by dust, smoke, salt or corrosive vapours; d) average humidity: not exceeding 95 %; and e) negligible vibration from external causes. NOTE 1 For any special service conditions that differ from the normal conditions defined in 1.6, agreement should be reached between the purchaser and the supplier on the conditions for use of the equipment. 3

7 NOTE 2 For low-voltage auxiliary equipment, no special precautions need be taken if the altitude is below m. NOTE 3 For internal insulation other than air at atmospheric pressure, the dielectric characteristics are identical at any altitude and no special precautions need be taken. NOTE 4 In the case of switchgear panels which are to be subjected to type or routine dielectric tests at an altitude above m a correction factor as set out in SANS will need to be applied to the relevant standard reference atmospheric test voltage. 2 Normative references The following documents contain provisions which, through reference in this text, constitute provisions of this standard. All standards are subject to revision and, since any reference to a standard is deemed to be a reference to the latest edition of that standard, parties to agreements based on this standard are encouraged to take steps to ensure the use of the most recent editions of the standards indicated below. Information on currently valid national and international standards can be obtained from Standards South Africa. BS 3693, Recommendations for design of scales and indexes on analogue indicating instruments. BS 5825, Specification for low-voltage switchgear and controlgear for industrial use. Mounting rails, G-profile for the fixing of terminal blocks. BS 7729, Instrument transformer - Three-phase voltage transformers for voltage levels having Um up to 52 kv. IEC , Direct acting indicating analogue electrical-measuring instruments and their accessories - Part 1: Definitions and general requirements common to all parts. IEC , Direct acting indicating analogue electrical-measuring instruments and their accessories - Part 2: Special requirements for ammeters and voltmeters. IEC , Direct acting indicating analogue electrical-measuring instruments and their accessories - Part 7: Special requirements for multi-function instruments. IEC , Direct acting indicating analogue electrical-measuring instruments and their accessories - Part 8: Special requirements for accessories. IEC , Direct acting indicating analogue electrical-measuring instruments and their accessories - Part 9: Recommended test methods. IEC , Guide for the determination of thermal endurance properties of electrical insulating materials - Part 1: General guidelines for ageing and evaluation of test results. IEC , Guide for the determination of thermal endurance properties of electrical insulating materials - Part 2: Choice of test criteria. IEC , Guide for the determination of thermal endurance properties of electrical insulating materials - Part 3: Instructions for calculating thermal endurance characteristics - Section 1: Calculations using mean values of normally distributed complete data. IEC , Guide for the determination of thermal endurance properties of electrical insulating materials - Part 4: Ageing ovens - Section 1: Single-chamber ovens. IEC , Guide for the determination of thermal endurance properties of electrical insulating materials - Part 5: Guidelines for the application of thermal endurance characteristics. 4

8 IEC , Polyvinyl chloride insulated cables of rated voltages up to and including 450 V/750 V - Part 3: Non-sheathed cables for fixed wiring. IEC , Polyvinyl chloride insulated cables of rated voltages up to and including 450 V/750 V - Part 4: Sheathed cables for fixed wiring. IEC , Polyvinyl chloride insulated cables of rated voltages up to and including 450 V/750 V - Part 5: Flexible cables (cords). IEC 60376, Specification and acceptance of new sulphur hexafluoride. SANS 97 (SABS 97), Electric cables - Impregnated paper-insulated metal-sheathed cables for rated voltages 3,3/3,3 kv to 19/33 kv (excluding pressure assisted cables). SANS 156 (SABS 156), Moulded-case circuit-breakers. SANS 1091 (SABS 1091), National colour standards for paint. SANS 1574 (SABS 1574), Electric cables - Flexible cords and flexible cables. SANS 1652 (SABS 1652), Battery chargers - Industrial type. SANS 5147 (SABS SM 147), Resistance to scratching of paint films. SANS 5159 (SABS SM 159), Adhesion of paint and varnish films (cross-cut test). SANS 7253/ISO 7253 (SABS ISO 7253), Paint and varnishes - Determination of resistance to neutral salt spray (fog). Amdt 1 SANS (SABS ), The selection, handling and installation of electric power cables of rating not exceeding 33 kv - Part 13: Testing, commissioning and fault location. SANS /IEC , Instrument transformers - Part 1: Current transformers. SANS /IEC , Instrument transformers - Part 2: Inductive voltage transformers. SANS 60186/IEC (SABS IEC 60186), Voltage transformers. SANS /IEC (SABS IEC ), High-voltage switches - Part 1: Switches for rated voltages above 1 kv and less than 52 kv. SANS /IEC (SABS IEC ), Low-voltage fuses - Part 1: General requirements. SANS /IEC (SABS IEC ), Low-voltage fuses - Part 2: Supplementary requirements for fuses for use by authorized persons (fuses mainly for industrial application). SANS /IEC , High-voltage fuses - Part 1: Current-limiting fuses. SANS 60298/IEC (SABS IEC 60298), A.C. metal-enclosed switchgear and controlgear for rated voltages above 1 kv and up to and including 52 kv. SANS 60694/IEC 60694, Common specifications for high-voltage switchgear and controlgear standards. 5

9 SANS /IEC , Low voltage switchgear and controlgear - Part 1: General rules. SANS /IEC , Low-voltage switchgear and controlgear - Part 3: Switches, disconnectors, switch-disconnectors and fuse-combination units. SANS /IEC (SABS IEC ), Low voltage switchgear and controlgear - Part 5-1: Control circuit devices and switching elements - Electromechanical control circuit devices. SANS /IEC (SABS IEC ), High voltage switchgear and controlgear - Part 100: High-voltage alternating current circuit-breakers. Amdt 1 SANS /IEC , High-voltage switchgear and controlgear - Part 102: Alternating current disconnectors and earthing switches. Amdt 1 SANS /IEC , High-voltage switchgear and controlgear - Part 105: Alternating current switch-fuse combinations. Amdt 1 3 Definitions For the purpose of this standard, the following terms, definitions and abbreviated terms apply: NOTE All the terms used in this standard are generally consistent with the definitions given in IEC (441). 3.1 approval acceptance, agreed to in writing, by the purchaser 3.2 "a" contact (make contact) a control or auxiliary contact that is closed when the main contacts of the mechanical switching device are closed and open when they are open 3.3 "b" contact (break contact) a control or auxiliary contact that is open when the main contacts of the mechanical switching device are closed and closed when they are open 3.4 bus-coupler switchgear panel a switchgear panel that is used to open and close the electrical connection and provide safety isolation between two busbar systems of a switchboard with a double busbar configuration. It could include a switch-disconnector or a circuit-breaker 3.5 bus-section switchgear panel a switchgear panel that is used to open and close the electrical connection and provide safety isolation between two sections of busbar of a switchboard. It could include a switch-disconnector or a circuitbreaker 3.6 circuit-breaker a mechanical switching device that is capable of making, carrying and breaking currents under normal circuit conditions, and also of making, carrying for a specified time and breaking currents under specified abnormal conditions, such as those of a short-circuit 6

10 3.7 circuit-breaker class B a circuit-breaker so designed as to not require maintenance of the interrupting parts of the main circuit during the expected operating life of the circuit-breaker, and only minimal maintenance of its other parts NOTE Minimal maintenance might include aspects such as lubrication, replenishment of gas, and cleaning of external surfaces. 3.8 circuit-breaker panel a switchgear panel complete with a fixed or withdrawable circuit-breaker 3.9 circuit-side the side of a circuit-breaker or switch that contains the cable connections and that can be isolated from the busbars 3.10 earthing position (of a withdrawable part) the position of a withdrawable part in which the closing of a mechanical switching device causes a main circuit to be short-circuited and earthed 3.11 independent manual operation a stored energy operation where the energy originates from manual power stored and is released in one continuous operation, such that the speed and force are independent of the action of the operator 3.12 joggle chamber a purpose designed panel used to align the busbars of different types of metal-clad switchgear 3.13 metal-clad switchgear metal-enclosed switchgear in which certain components, for example, circuit-breakers, are arranged in separate compartments that have metal partitions and that are intended to be earthed NOTE This term applies to metal-enclosed switchgear with metal partitions that provide the degree of protection, or a higher degree, included in table 1 of SANS and that has separate compartments for the following: a) each main switching device; b) components connected to one side of a main switching device, for example, a feeder; and c) components connected to the other side of the main switching device, for example, busbars moulded-case circuit-breaker (MCCB) a circuit-breaker that has a supporting housing of moulded insulating material that forms an integral part of the circuit-breaker 3.15 rated insulation level the combination of the rated lightning impulse withstand voltage and the rated short duration power frequency withstand voltage specified in SANS

11 3.16 rated normal current for main circuits and switching devices, the r.m.s. value of the current that they are designed to carry continuously under the specified conditions of use and behaviour NOTE Some main circuits of switchgear, for example, busbars and feeder circuits might not have the same value of rated normal current rated peak withstand current for main and earthing circuits, the peak current associated with the first major loop of the short-time withstand current that a mechanical switching device is designed to carry in the closed position under prescribed conditions of use and behaviour 3.18 rated short-time withstand current for main and earthing circuits, the r.m.s. value of current that the switching device is designed to carry in the closed position during a specified short time under prescribed conditions of use and behaviour 3.19 rated voltage the highest r.m.s. phase-to-phase voltage of the supply on which the switchgear is designed to operate 3.20 relay chamber a metal-enclosed chamber that contains control, measuring, indicating, alarm, protective and regulating equipment associated with a switchgear panel 3.21 service position (of a withdrawable part) the position of a withdrawable part, in which it is fully connected for its intended function 3.22 stored energy operation (of a mechanical switching device) an operation that is completed under predetermined conditions by using energy stored in the switching device prior to the completion of the operation 3.23 switch a mechanical switching device that is capable of making, carrying and breaking currents under normal circuit conditions, which can include specified operating overload conditions, and also capable of carrying for a specified time, currents under specified abnormal circuit conditions such as those of a short-circuit NOTE A switch can be capable of making but not breaking short-circuit currents switchboard two or more switchgear panels coupled together in various combinations 3.25 switch-disconnector a switch that, in the open position, satisfies the isolating requirements specified for a disconnector 3.26 switch-disconnector panel a switchgear panel complete with a non-withdrawable type of switch-disconnector or switch-isolator 8

12 3.27 switch-fuse combination a switch in which at least one pole has a fuse in series in a composite unit 3.28 switch-fuse combination panel a switchgear panel complete with a non-withdrawable switch-fuse combination 3.29 switchgear a general term that covers switching devices and their combination with associated control, measuring, indicating, alarm, protective and regulating equipment, also assemblies of such devices and equipment with associated interconnections, accessories, enclosures and supporting structures, intended, in principle, for use in connection with the generation, transmission, distribution and conversion of electric energy NOTE When reference is made in this part of the specification to a switchgear panel and a switchboard, the term switchgear is used switchgear panel (or panel) switchgear of modular design that comprises a mechanical switching device, for example, a circuitbreaker, a switch-disconnector, a switch-fuse combination or a switch 3.31 terminal assembly two or more terminals fixed to the same conductive part 3.32 terminal block an insulating part carrying one or more mutually insulated terminal assemblies and intended to be fixed to a support 3.33 test position (of a withdrawable part) the position of a withdrawable part in which an isolating distance or segregation is established in the main circuit, and in which the auxiliaries are connected 4 Requirements 4.1 Ratings Main circuits Rated voltage The rated voltage shall be one of the following, as specified in schedule A: a) 7,2 kv; b) 12 kv; c) 24 kv; and d) 36 kv. 9

13 Rated frequency The rated frequency shall be 50 Hz Rated normal current Preferred rated normal currents are: a) 630 A; b) 800 A; c) A; d) A; and e) A. NOTE The required rated normal current is specified in the configuration drawing (see , and ) Rated insulation level The rated insulation level of switchgear shall be in accordance with table 1 for the relevant rated voltages. NOTE Where the switchgear is fed from an overhead distribution system by a short length of cable, the equipment could be exposed to higher voltages than those set out in table 1 unless protective measures are taken. For cable lengths of 100 m or more surge arresters should be used at both ends of the cable. For cable lengths less than 100 m surge arresters should be used at the pole where there is a change from cable to overhead lines If a 75 kv rated peak lightning impulse withstand voltage is required for 12 kv switchgear, it will be specified in schedule A. NOTE Generally 95 kv is specified for use at altitudes above m. Table 1 Rated insulation level 1 Rated voltage 7, Rated peak lightning impulse withstand voltage (see ) Voltages in kilovolts 3 Rated short-duration powerfrequency withstand r.m.s. voltage Rated short-time and peak withstand current The rated short-time and peak withstand currents shall be in accordance with table In the case of 12 kv switchgear, the rated short-time withstand current, as selected from table 2, will be specified in schedule A The standard value of short-time current duration is 3 s. 10

14 Table 2 Rated short-time and peak withstand currents Rated Rated short-time Rated peak voltage withstand r.m.s. current withstand current kv ka ka 7, Rated breaking current Switches shall be capable of breaking the following currents: a) the rated closed loop breaking current, which is equal to the rated normal current; b) the rated mainly active load breaking current, which is equal to the rated normal current; and c) the rated cable-charging current, which is standardized at 10 A Rated short-circuit breaking current The rated short-circuit breaking current of circuit-breakers and switch-fuse combinations shall be equal in value to the rated short-time withstand current given in column 2 of table 2 that corresponds to the relevant rated voltage given in column 1 of table Rated short-circuit making currents The rated short-circuit making current of circuit-breakers, switch disconnectors, earthing switches and switch-fuse combinations shall be equal in value to the rated peak withstand current given in column 3 of table 2, corresponding to the relevant rated voltage given in column Auxiliary circuits The auxiliary supply voltage shall be a d.c. voltage of 110 V unless one of the following is specified in schedule A: a) an a.c. voltage of 110 V; b) an a.c. voltage of 230 V; or c) a d.c. voltage of 30 V. 4.2 Switchgear General Switchgear shall comply with the requirements of SANS NOTE For ease of reference, certain of the requirements in SANS are repeated in this standard Earthing switches shall comply with SANS

15 The following switchgear information shall be stated in schedule B: a) the manufacturer; b) the country of origin; c) catalogue/type designation; and d) the total switchgear mass The insulation co-ordination in air within the switchgear shall comply with the requirements given in annex C Internal arc tests shall be carried out in all medium-voltage power compartments (i.e. the compartment containing the mechanical switching device, the power cable enclosure and the busbar chamber). See annex B Physical requirements Switchgear shall be suitable for service in the system and environmental conditions specified in Each switchgear panel shall be a self-contained unit with a degree of protection of at least IP3X in accordance with SANS Separate metal compartments are required for the main switch; primary busbar; voltage transformers; power cable or current transformer and relay or control chamber The configuration of the switchboard shall conform to the configuration drawing (see 7.1(a)) Switchgear panels shall be floor mounted, shall be of modular design such that they can be joined together to form a complete switchboard of any combination of the switchgear panel types supplied and shall be readily extendible at either end All switchgear panels shall allow switching operations to be carried out from the front of the panel Where panel fronts are not aligned, it shall be possible to arrange switchgear panels in any order such that the equipment of each panel can be operated in the intended manner For single-busbar switchboards of simple design, switchgear panels shall be so designed that the cable termination compartments can be readily aligned to suit a cable trench of width 600 mm, with the front of the switchgear panels fully aligned Provision shall be made for lifting or slinging each panel. Details of the provisions shall be stated in the general arrangement drawing (see 7.2(b)) Switchgear panels shall be so constructed that they can be adapted readily (by the purchaser on site, if necessary) to incorporate a voltage transformer All padlocking facilities shall be suitable for padlocks that have shanks of diameter 6 mm Doors shall have stops to prevent them overswinging when opened. 12

16 4.2.3 Busbar All joints and tees in busbars and busbar connections shall be made using bolts, nuts and washers that are suitably protected against corrosion. Suitable methods of protection include phosphating, galvanizing, zinc impregnation and plating with copper, nickel, cadmium silver, tin or zinc. NOTE "Putty and tape" is not the preferred method to achieve the impulse dielectric ratings under normal operating conditions Busbar connections and tee-offs shall be capable of carrying both normal load and fault currents The busbar rated current shall be stated in the configuration drawing (see 7.1(a)) Installation If installation and on-site operational testing are required to be carried out by the supplier, it will be specified in schedule A. NOTE It is recommended that installation and on-site operational testing be done by the supplier Erection shall be in accordance with the purchaser's switch room layout drawing. See 7.1(b) The tolerance of the switch room finished floor level shall be less than or equal to 2 mm/m 2 in the area required to withdraw a circuit-breaker and less than or equal to 1 mm/m 2 elsewhere The availability and the type of constructional power supply available on site will be specified in schedule A Extension of switchboards If the switchgear is to be joined to an existing switchboard, this will be specified in schedule A If the switchgear is to be joined to an existing switchboard, the details of the existing switchboard will be specified in schedule A. NOTE Where the purchaser cannot supply the drawings for the original switchgear, the manufacturer of the original switchgear is expected to supply the required drawings If a joggle chamber is required, the supplier shall provide an outline drawing of the joggle chamber or shall specify the joggle chamber width The supplier shall by design criteria, calculations or test, prove that after the extension of a switchboard, the joggle chamber and the new part of the switchboard comply with the requirements of this standard Heaters The supplier shall state in schedule B if heaters will be installed in the switchgear The type of heater offered shall be stated in schedule B Surge arresters If surge arresters are required in feeder switchgear panels, this will be specified in schedule A. 13

17 The type and position of the surge arresters will be specified in schedule A Surge arresters shall be earthed by bonding to the earthing bar (see 4.2.8) with copper cable of cross-sectional area not less than 150 mm Earthing bar Each switchgear panel shall include a copper earthing bar at least 25 mm wide with a crosssectional area of at least 125 mm 2, to facilitate earthing of cable sheath(s) and armour. The earthing bar shall be suitable for interconnection to the adjacent switchgear panels. The current density in the earthing conductor shall not exceed 200 A/mm 2 under the earth fault conditions specified in schedule A. The type of system earthing (solid/resistive) will be stated in schedule A Suitable facilities for termination of the earths (preferably M12 clearance holes or studs) shall be provided. The clearance hole or stud size of the earth bar offered shall be stated in schedule B Sulfur hexafluoride (SF 6 ) insulation If SF 6 is used for insulation (not as an interruption medium) this shall be stated in schedule B together with the compartments where SF 6 is used Sulfur hexafluoride switchgear shall be filled with new SF 6 that complies with the requirements of IEC The switchgear shall be factory sealed so that it does not require routine gas replenishment in normal service. The design, construction and sealing of gas compartments shall be such that, the period to replenishment of gas is not less than 20 years Unless specified otherwise in schedule A, a device for monitoring the SF 6 pressure in each tank, even in service, with indication of minimum permissible pressure level for safe operation shall be provided If fitted, the pressure level monitoring device shall be clearly visible to the operator from the operating side of the switchgear panel The quantity of the SF 6 to be used in each separately filled compartment shall be stated in schedule B The supplier of SF 6 switchgear shall render a service to recover and replenish SF 6 gas after its service life. Confirmation of this shall be in writing at tender stage. 4.3 Circuit-breaker panels Withdrawable and fixed type NOTE Common requirements for withdrawable circuit-breaker panels and fixed circuit-breaker panels are given in Specific requirements for withdrawable circuit-breaker panels and fixed circuit-breaker panels are given in and respectively General The current rating of the circuit-breaker switchgear panel shall be stated in the configuration drawing (see 7.1(a)) All circuit-breakers shall be class B in accordance with SANS

18 The interrupting medium offered shall be either vacuum or SF 6 and shall be stated in schedule B Circuit-breakers shall comply with the requirements of SANS Amdt Indication The circuit-breaker panel shall have indication clearly visible from the front of the panel (i.e. either on the circuit-breaker or on the circuit-breaker panel) Interlocks Facilities provided for operational access to parts of the switchgear panel that contain live components shall be mechanically interlocked so that access to such parts is not possible unless all live parts have been rendered safe, either by a visibly applied earth connection or by being positively disconnected and screened from the remaining live parts Mechanical interlocks shall be provided to ensure positive and substantial protection against malfunction, and shall be so designed and constructed as to ensure dependable fail-safe operation When the circuit-breaker panel is padlocked in the earth position, it shall not be possible to gain access to the cable test facility. NOTE This interlock will prevent the undesirable removal of the cable earthing Earthing If specified in schedule A, earthing facilities shall be provided for all main circuits If specified in schedule A, a busbar earthing facility shall be provided If specified in schedule A, a bus section earthing facility shall be provided Details of the earthing facilities offered shall be stated in schedule B The frame of each earth switch shall have a reliable earthing terminal that has a clamping screw for connection to an earth conductor rated for the specified fault conditions. The diameter of the clamping screw shall be preferably M12 and shall be stated in schedule B The earthing terminal shall be marked in accordance with (c) Where bus-section or bus-coupler panels are supplied, they may be used to provide integral earthing of either set of busbars connected to them. This feature shall be fully detailed in schedule B Circuit-breaker operating mechanisms The circuit-breaker operating mechanism shall be an integral part of the circuit-breaker Local electrical operation If OPEN/CLOSE control switches are specified in schedule A, they shall be the pistol-grip type and shall be arranged for spring return to the neutral position when released The closing operation shall be initiated by clockwise rotation of the control switch and padlocking facilities shall be provided for the OPEN/CLOSE control switch in the neutral position. NOTE For safety reasons it is strongly recommended that switching operations be done from a remote position. 15

19 Remote control unit A panel connector for hand-held remote control shall be provided A suitable, self-retaining panel connector shall be supplied. The plug-in position of the panel connector should be at the front of the switchgear panel The pins for the tripping and closing of the circuit-breaker shall be as follows: a) pins 1 and 2 for trip; b) pins 3 and 4 for close; and c) pins 5 and 6 for charging (if electrical charging is specified in schedule A). NOTE It is accepted that letters A to F could be used instead of numbers 1 to 6 respectively Mechanical operation A padlockable mechanical trip facility shall be provided If mechanical close is specified in schedule A, it shall be supplied with provision for padlocking Electrical operation Unless specified otherwise in schedule A, or in the case of an auto-reclose circuit-breaker, the closing mechanism shall be the stored energy type, which shall be manually charged, and the closing operation shall be initiated mechanically In the case of a spring-charged closing mechanism with a coil-operated release, the total coil power shall not exceed 1,5 kw per circuit-breaker Where applicable, the a.c. supply voltage and ratings of the spring charge motor will be specified in schedule A Where applicable, the d.c. supply voltage, the peak power and the steady power of the springs charge motor ratings will be specified in schedule A In the case of a solenoid-operated closing device, the input power required shall not exceed 15 kw per circuit-breaker The type of circuit-breaker closing mechanism offered shall be stated in schedule B The rating of each circuit-breaker closing device shall be stated in schedule B The electrical tripping circuit of a circuit-breaker shall consist of either a d.c. shunt trip coil with an adequately rated "a" contact in series or an a.c. shunt trip coil with either a time lag fuse or an MCCB shunting the trip coil If applicable, any alternative tripping methods required will be specified in schedule A In the event of series tripping the following shall apply: a) the trip coil shall be connected to a current transformer of suitable characteristics; b) the trip coil shall be shunted by normally closed contact of a relay or other protective device such as a time lag fuse or MCCB which opens out on operation, thus diverting the current through the trip coil; 16

20 c) for low ratio current transformers, for example, less than 100:1, it might be necessary to demonstrate the performance at the commissioning stage; and d) all designs shall include a separate trip coil for each pole of the relay or protective device. Thus a two overcurrent and one earth fault arrangement would require two trip coils on the phases associated with the overcurrent protective devices and a trip coil in the residual circuit Circuit-breaker operation coils If applicable, the circuit-breaker shall have one close coil and one trip coil A shunt closing coil release shall operate correctly at a voltage of 85 % to 110 % of the rated supply voltage. A shunt opening release shall operate correctly at a voltage between 70 % in the case of d.c. or 85 % in the case of a.c., and 110 % of the rated supply voltage, measured at the terminals of the device. The circuit-breaker shall close when an electrical pulse of 100 ms is applied to the closing coil All operating coils of the control contactors associated with the solenoid-operated closing device shall be rated for continuous operation Voltage and peak power ratings for continuous operation of the circuit-breaker coils shall be stated in schedule B Circuit-breaker auxiliary contacts Auxiliary contacts shall be rated for 10 A, 230 V in the case of a.c.; and 10 A, 110 V in the case of d.c Circuit-breakers shall have auxiliary "a" and "b" contacts that are fitted on the chassis of the circuit-breaker and that follow, positively, the action of the main contacts of the circuit-breaker The number of each type of auxiliary contacts shall suit the requirements of the electric close, trip, control and alarm circuits plus the spares specified in schedule A The number of spare contacts offered shall be stated in schedule B All spare contacts specified in shall be wired to the auxiliary cable termination box and the wires shall be labelled as detailed in If specified in schedule A, the circuit-breaker auxiliary contacts shall be wired to the compartment behind relay chamber doors Application guidelines All feeder circuit circuit-breakers in the closed position shall be able to trip-close-trip before the spring needs to be charged again Transformer or feeder circuit circuit-breakers panels shall be the XEM type (stored energy operation by means of energy stored in a motor-charged spring with manual or electrical release) Circuit-breakers shall be used in bus section and bus coupler panels Bus section circuit-breakers panels shall be the XM type (stored energy operation by means of energy stored in a manually-charged spring with mechanical release) or the XEM type. 17

21 4.3.2 Withdrawable type circuit-breaker General Circuit-breakers shall be withdrawable with a self-alignment device Robust guides and self-aligning main contacts shall ensure that the connection of the circuitbreaker and the fixed panel contacts are correctly made when the circuit-breaker is racked into the service or earthing position. Under no circumstances shall the circuit-breaker bushings be used for alignment of the circuit-breaker unit Movement of the circuit-breaker into and out of the service or earthing position shall be by a mechanical driving system (for example, a lever, ratchet or screw or thread), which shall ensure positive location without any possibility of overrun or of damage to contacts or insulation components All auxiliary plugs and sockets for making and breaking the control circuits of the circuitbreaker shall be self-aligning with guide pins and contacts of a proven robust type. In order to achieve interchangeability, the position and control circuit function of these contacts shall be the same on all categories of circuit-breaker switchgear panels of the same ratings Each circuit-breaker shall be interchangeable with other circuit-breakers of the same rating in respect of main circuits and control circuits The circuit-breaker interrupting medium (see ), manufacturer, country of origin, model or type designation, total circuit-breaker mass (cart included) and rating nameplate position shall be stated in schedule B The isolation displacement of the circuit-breaker (either vertical or horizontal) shall be stated in schedule B Indication The circuit-breaker panel shall have the following definite indication: a) circuit-breaker open/close (which, where applicable, shall be visible with the circuit-breaker in any position); b) circuit-breaker racked in/out; c) circuit-breaker isolated/test (if applicable); d) stored energy device charged/discharged; e) in the case of double busbars, the set to which the circuit-breaker is connected; f) earth position; and g) non-resettable mechanical operation counter Interlocks Interlocks shall ensure that a) the withdrawal or engagement of a circuit-breaker is impossible unless it is in the open position, b) the operation of a circuit-breaker is impossible unless it is in the service, disconnected, removed, test or earthing position, and c) it is impossible to close the circuit-breaker in the service position unless it is connected to the auxiliary circuit, or it is designed to open automatically without the use of an auxiliary circuit. 18

22 It shall not be possible to insert a circuit-breaker into a circuit of a different rating or of a different main isolating contact arrangement Where a withdrawable circuit-breaker is used for earthing, the electrical tripping circuit of a circuit-breaker shall be isolated when the circuit-breaker is in the earthing position Earthing All earthing switches shall be either a) an integral type, that uses the circuit-breaker, b) an integral type, that uses a fixed earthing switch mounted for this purpose in the circuit-breaker panel, or c) a specially designed earth truck The type of earthing switch offered shall be stated in schedule B Padlock facilities Facilities shall be provided to padlock a) all orifice shutters individually in the closed position, b) the circuit-breaker in each of the service, isolated/test and earthing positions, c) integral earth switches in both the open and earthing positions, and d) the mechanical tripping device in the case where the circuit-breaker is used for earthing. NOTE See for padlock details Safety shutters Safety isolation shall be achieved by racking the circuit-breakers away from the main circuit connection orifices. These orifices shall be so covered, automatically, with mechanically operated metal safety shutters, as to prevent inadvertent contact with the busbar and circuit conductors of the fixed part of the switchgear panel when the circuit-breaker is racked out Circuit and busbar orifice shutters shall be arranged to operate independently. For testing purposes, it shall be possible to retain, but not lock, all the shutters in the open position Busbar orifice shutters shall be painted signal red in accordance with colour A11 of SANS 1091 and inscribed in accordance with and, when relevant, Circuit orifice shutters shall be painted canary yellow in accordance with colour C61 of SANS Safety shutters shall be operated without lubrication. Safety shutters shall not rely only on gravity but be mechanically driven in both directions All removable busbar covers shall be red. 19

23 Circuit-breaker transporting device Each circuit-breaker shall be removable on a transporting device with wheels The circuit-breaker transporting device shall be either integral or external and the type offered shall be stated in schedule B Where external transporting devices are provided, they shall align with the circuit-breaker Where external transporting devices are provided, two transporting devices per circuitbreaker rating shall be provided Circuit-breaker earth terminal Each circuit-breaker shall be fitted with an earthing terminal to facilitate testing of earth continuity between the circuit-breaker carriage and the switchgear main earth bar The circuit-breaker earthing terminal shall be easily accessible from the front of the circuitbreaker The circuit-breaker earthing terminal shall be labelled in accordance with (c) The connection between the circuit-breaker earthing terminal and the main carriage earth shall be of sufficient cross sectional area to handle the fault conditions specified in Fixed type circuit-breaker General A circuit-breaker panel shall satisfy the isolating requirements specified for a disconnector in SANS Amdt The circuit-breaker interrupting medium (see ), manufacturer, country of origin, model or type designation, total circuit-breaker mass and rating nameplate position shall be stated in schedule B If the circuit-breaker panel includes an in-line disconnector, the number of disconnectors shall be stated in schedule B It shall be stated in schedule B whether a three or two position disconnector(s) is offered Indication The circuit-breaker switchgear panel shall have the following definite indication: a) circuit-breaker open/close; b) disconnector open/close (if applicable); c) earth position; d) stored energy device charged/discharged; e) in the case of double busbars, the set to which the circuit-breaker is connected; and f) non-resettable mechanical operation counter. 20

24 Interlocks Interlocks shall ensure that the disconnector cannot be moved from the closed position unless the circuit-breaker is open Interlocks shall ensure that operation of the circuit-breaker is not possible, unless the disconnector is in the closed, open or earth (if provided) position Positive mechanical interlocking shall be provided to prevent inadvertent switching from the ON position to the EARTH position without a definite stop in the OFF position, or from the EARTH position to the ON position without a definite stop in the OFF position Access to the test terminals shall only be possible when the associated earth switch is in the EARTH position When the circuit test facility is in use, it shall not be possible to close the disconnector If the earthing of a circuit-breaker panel is not visible from the operating position, the corresponding indication shall be directly coupled to the earthing mechanism, to ensure fail-safe indication Interlocks shall be provided for the circuit-breaker, to ensure that the circuit-breaker cannot be closed when the earth is in the closed position Earthing Earth switches shall be the integral type Padlocking Facilities shall be provided to padlock a) the circuit-breaker in the closed and open positions, and b) if applicable, the disconnector in the closed, open and earth positions Test circuits If so specified in schedule A, the circuit-breaker panel shall incorporate an integral type circuit test facility All test facilities shall be suitable for the application of d.c. test voltages associated with the after-installation testing of power cables, and shall be rated for the same system voltage as the switchgear For testing, the site test values specified for XLPE cables in SANS and for PILC cables in SANS 97 shall apply The type of test facility offered shall be stated in schedule B The test plugs in any test pack that is supplied (see ) shall be fully described in schedule B. 21

25 4.4 Switch-disconnector panels General A switch-disconnector panel shall have a non-withdrawable three-pole switch-disconnector The rated current shall be specified in the configuration drawing (see 7.1(a)) The switch-disconnector shall comply with the requirements of SANS and SANS Amdt If specified in schedule A, the switch disconnector shall incorporate an integral three-poleearthing switch on the circuit-side The type of switch-disconnector offered shall be stated in schedule B The operating mechanism of the switch-disconnector shall be independent manual closing and opening Interlocks Positive mechanical interlocking shall be provided to prevent inadvertent switching from the ON position to the EARTH position without a definite stop in the OFF position, or from the EARTH position to the ON position without a definite stop in the OFF position Padlocking facilities shall be provided to lock the switch in any position, and to prevent the selection of the ON position while permitting operation from OFF to EARTH or from EARTH to OFF Access to the test terminals shall only be possible when the associated earth switch is in the EARTH position When the circuit test facility is in use, it shall not be possible to close the switch-disconnector When the switch-disconnector panel is padlocked in the earth position, it shall not be possible to gain access to the cable test facility. NOTE This interlock will prevent the undesirable removal of the cable earthing Test circuits If so specified in schedule A, the switch-disconnector shall incorporate an integral type of circuit test facility The type of test facility offered shall be stated in schedule B The test plugs in any test pack if supplied (see ) shall be fully described in schedule B. 4.5 Switch-fuse combination panels General Switch-fuse combination panels shall have a non-withdrawable three-pole switch-fuse combination The rated current shall be specified in the configuration drawing (see 7.1(a)). 22