Annex B1 – Technical Specifications Technical Specification for Main 415V Switchboard 1. GENERAL a) The switchboards shall be of the indoor, metal clad, modular type suitable for operation in the switch room as indicated on the drawings. It shall be capable of operating in tropical and humid conditions. b) The switchboards shall be totally enclosed and constructed as described below. They shall comply with the requirements of the latest edition of EN 60439-1. c) The design of the switchboard shall comply fully with A.S.T.A. Full type test requirements. d) The switchboards shall be suitable for operation on 415 Volts, 3-Phase, 4- Wire, 50Hz system with solidly earthed neutral. 1.1 Fault Rating The switchboards shall be designed to withstand a prospective fault level of 75 kA at 415 Volts 3 phase (symmetrical) for 3 seconds in accordance with the test procedures laid down in the EN standards. 1.2 Construction a) The switchboards shall be naturally cooled, self-contained, metal-enclosed type, floor mounted, flush-fronted and suitable for front and rear access, bottom and top cable entry. b) All structural works shall be adequately protected against corrosion. The basic materials shall be properly pre-treated before the final coats of resistant finishing paint are applied. c) Construction of the switchboards shall be minimally Form 3B separation as per EN 60439-1. d) The degree of protection for the switchboards shall be minimally IP 30 as per EN 60529. The floor shall not be considered as part of the enclosure. e) The partitions or barriers for internal separation of assemblies shall designed to obtain Form 3B separation of compartments shall comply to degree of protection IP 20 as per EN 60529. f) The switchboards shall provide complete with all ACB, MCCB and other electrical components necessary for the correct operation and protection of the installation as described in this specification and shown on the drawings. g) All operating devices shall be mounted for operation at the front of the switchboard. Page 1 of 38 Annex B1 – Technical Specifications h) The enclosure shall be fabricated from electro galvanized steel sheet with epoxy powder coating. The sheet steel thickness shall not be less than 2.0mm for structural member and 1.5mm for doors. i) The front and rear covers of the switchboard shall be hinged door type. Doors shall be effectively earthed to the fixed enclosure. All doors to be arranged to open through a minimum of 120 degrees, it must be possible to easily remove the door without disturbing other doors in the module. j) Compartment doors or cover shall be interlocked to prevent opening when the isolating device is in the "ON" position. The isolating device shall only be operable when the door is fully closed. It must be possible to defeat the interlock for testing purposes once the door is open. 1.3 Busbars and Connections a) The busbars shall be of plain hard-drawn, high conductivity, electrolytic copper bars in accordance with BS EN 13601 and of adequate rectangular cross-section to carry continuously the specified current without overheating and shall be rigidly mounted on non-hygroscopic glass fibre reinforced polyester so as to withstand any mechanical force to which they may be subjected under maximum fault condition. b) All busbars shall be tinned and coloured red, yellow, blue, black and green at appropriate points to distinguish the phases, neutral and earth. No tapes shall be used. The main busbars should be located at the front upper lever in a horizontal plane and equally paced as specified in EN. All busbars system shall have short circuit rating of not less than 75 kA at 415 volts for 3 seconds. c) The busbar system shall be readily accessible for inspection, construction and maintenance duties without the requirement of additional equipment. In case of a busbar short circuit, it shall be possible to clean or to replace the busbars and support system without stripping the assembly. d) In the busbar compartment the phase busbars may not be fully insulated. However, each phase busbar shall be able to withstand at least an applied AC test voltage of 2.5 kV for a period of 60 seconds. e) The neutral busbar shall be the same size as that of the phase busbar. f) The earth busbar shall be provided internally throughout the full length of each switchboard and shall be not less than 50mm X 6mm. 1.4 Secondary Wiring, Core Identification and Termination a) The conductor size shall be minimum 1.5mm² with minimum 300V, PVC insulation. b) All control wiring shall be colour coded, carried out in neat, systematic manner and securely fixed by insulated cleats or approved method and arranged such that Page 2 of 38 Annex B1 – Technical Specifications access to any apparatus or connection point is not impeded. Where inter-panel wiring passes through panel side sheets etc., the access hole shall be fitted with a suitable grommet. c) Sleeve type identification ferrules shall be fitted on all wires at both ends. The sleeve or ferrules shall be of insulating material, which, except where otherwise specified, shall be white with black lettering and shall have a glossy finish. The sleeve or ferrules shall be unaffected by oil or damp. d) All control wire shall be separately terminated with tinned crimped lugs of approved type suitable for the terminal and wire use. e) Colour coding of secondary wiring shall be in accordance with IEC 446. Earth wires shall be green/yellow striped. Wiring between two terminals shall be continuous. Joints or interconnections are not allowed and no more than two wires shall be connected under one terminal connection. f) Terminal studs or blocks shall be adequately rated for the duty. Terminals shall be identified using an approved marking and numbering system. 1.5 Switchboard Components 1.5.1. Air Circuit Breakers a) All Air Circuit Breakers shall be manufactured and tested to comply fully with EN 60947-2 and shall have integral with built-in micrologic control unit. The Air Circuit Breakers shall be rated to carry continuously, the full load current currents of their respective circuits. The minimum rated short time fault capacity shall not be less than 75 kA for 1 second to EN 60947-2. The main contacts shall be of the double break type. Contacts shall be replaceable and of the silver-plated type. Individual arc chutes shall be provided on each pole of the breaker and so designed that any arc caused by the opening of breaker under maximum fault condition shall be contained completely in the chute. b) All operating mechanisms shall have mechanical 'ON' and 'OFF' indicators and whether they are in the 'Connected', 'Test' or 'Disconnected' positions. Hand charged spring mechanisms shall have mechanical indicators to show 'SPRING CHARGED' and 'SPRING DISCHARGED'. c) All incoming & outgoing Air Circuit Breaker shall be draw out type. d) If indicated on drawings, Air Circuit Breaker used for bus coupler shall be 4 pole fixed or draw out type. e) Mechanical & electrical interlocks shall be provided in cases where multiple incoming supplies are not to be paralleled. 1.5.2. Moulded Case Circuit Breakers a) Moulded Case Circuit Breakers shall comply with EN 60947-1 and EN 60947-2 and shall have adjustable thermal-magnetic or electronic tripping devices. They shall be fully tropicalised and suitable to be used up to an ambient temperature of Page 3 of 38 Annex B1 – Technical Specifications 40°C, enclosed in glass-reinforced polyester moulded case and suitable for use on 240/415V, 50Hz A. C. supply system. b) They shall be of the quick-make, quick-break type having manually operable toggle type handle. Permanent position indicators shall be provided to show status of the breaker. They shall have trip-free feature to prevent the breaker from being closed against fault conditions. Multi pole shall have common trip operating mechanism for simultaneous operation of all poles. c) Unless otherwise specified in the drawing and or Bill of Quantities, the minimum A.C. Interrupting capacity of the breakers shall be 75 kA rms(symmetrical) at 415 volts for switchboards connected to transformer. The rated service short circuit breaking capacity (Ics) shall be 100% of the rated ultimate short circuit breaking capacity (Icu) at 415 volts. d) They shall have facilities for shunt trip, auxiliary contacts accessories for externally connected tripping, alarm & indication purposes if necessary. e) All breakers where the incoming or outgoing feeder shall provide with panel mounted external operating handle with padlocking facilities and door interlocking facilities to prevent the panel door from being opened to access to the breakers in closed position. f) All breakers shall provide a bolted type solid neutral link fitted in the same compartment together with the phase poles. 1.5.3. Protection Relays a) Protection relays shall comply with EN 60255-8 and EN 60255-23. The protection relays shall operate as rapidly as reasonably practicable. b) Protection system shall be designed and applied to provide the maximum discrimination between faulty and healthy circuits. All protection equipment shall remain inoperative during transient, which may arise during switching or other disturbances to the system. Where contacts of protective relays are unable to deal directly with the tripping currents, approved auxiliary contactors or relays shall be provided. c) All protection relays shall be microprocessor base, 2 elements with 4 setting points & setting range as low as 10% of CT ratio discrimination flexibility. d) It shall be capable of logging and communicating with remote station and shall be integrated with Building control system. 1.5.4. Instruments a) The instruments for incomers shall be digital power meter capable to monitoring all the important electrical parameters including 3 phase current, voltage, power factor, kWhr, kVARhr, harmonics and maximum demand.