National Grid Substations Technical Specification NGTS 2.1 ...

1 National GridSubstationsTechnicalSpecificationNGT S 2 May 1 Scope .. 1 References .. 1 General 2 Performance 12 Test 14 Appendix 17 Appendix 21 Appendix 23 Authorised for Issue by:M B HumphriesGeneral ManagerTechnology and Science DivisionThe Electrical Standards for SHET ransmission s area are non-maintainedversions of National Grid TechnicalSpecifications that are applicable to the SHET ransmission System only. These specificversions are not subject to National Gridchange control and all queries about theirapplicability and content should be directed toSHE Transmission in the first instance. (ShouldUsers require the change controlled versionsof the GB Transmission System National GridTechnical Specifications please see theNational Grid Extranet or Livelink systemwhere applicable).

2 The National Grid Company plc 1995No part of this publication may be reproduced,stored in a retrieval system, or transmitted inany form or by any means electronic, mechanical,photocopying, recording or otherwise, withoutthe written permission of the NGC obtained fromthe issuing OfficeNational Grid HouseKirby Corner RoadCoventry CV4 8 JYRegistered inEngland and WalesNo. 2366977 Published by:The National Grid Company plcBurymead HousePortsmouth RoadGuildford, Surrey GU2 5 BNNGTS 1 Issue 2 May 1995 SUBSTATIONSFOREWORDThis Document defines the Technical requirements for Substations connected to The National Grid Companyplc (NGC) system and with equipment rated at 145, 300 or 420 kV. It is supported by the more specificNGTS documents at Level Specification is applicable to new construction and extensions to existing installations.

3 It shouldhowever be noted that where a Central Electricity Generating Board (CEGB) Standard' substation is to beextended the Contract may refer to obsolete Transmission Plant Specifications. 1 SCOPEThis functional Specification covers all types of substation with equipment installed for use on 132, 275 and400 kV 50 Hz systems. It is applicable to both open-terminal air-insulated (AIS) and metal-enclosed gas-insulated (GIS) substation constructions and covers equipment operated at lower voltages on the samesubstation site. All NGC plant and apparatus wholly within the substation and not covered more specifically by other ngts 'sis within the scope of this REFERENCESThe Health and Safety at Work Act Factories Act Electricity at Work Regulations 694 (BS 6581) Common Clauses for High-Voltage Switchgear and Controlgear 865 Calculation of the Effects of Short-Circuit 50-052 High-Voltage Switchgear and Controlgear for Industrial Use.

4 Cast Aluminium Alloy Enclosuresfor Gas-Filled High-Voltage Switchgear and 50-064 Wrought Aluminium and Aluminium Alloy Enclosures for Gas-Filled High-Voltage Switchgearand EN 50-068 Wrought Steel Enclosures for Gas-Filled High-Voltage Switchgear and EN 50-069 Welded Composite Enclosures of Cast and Wrought Aluminium Alloys for Gas-Filled High-Voltage Switchgear and EN 50-089 Cast Resin Partitions for Metal Enclosed Gas-Filled High-Voltage Switchgear EN 60-529 Classification of Degrees of Protection Provided by EN 61011 Safety Requirements for Mains Operated Electric Fence 1710 Specification for Identification of Pipelines and 5395: Part 3 Code of Practice for the Design of Industrial Type Stairs, Permanent Ladders 2 Issue 2 May 1995BS 7354 Code of Practice for Design of High-Voltage Open-Terminal 1 Overview, National Grid Switchgear for the National Grid Electronic Ancillary Light Current Equipment.

5 ngts Substation Interlocking Substation Substation Auxiliary Supplies (Publication Mid 1995). ngts Disconnectors and Earthing GENERAL Requirements for all Statutory RequirementsIn addition to the requirement specified in Clause of ngts 1, the manner in which plant and equipmentis installed as a system shall allow that system and its components to be operated and maintained withinthe requirements of principally The Health and Safety at Work etc Act 1974, The Factories Act 1961, TheElectricity at Work Regulations 1989, The Provision and Use of Work Equipment Regulations 1992 and TheElectricity Supply Regulations 1988 as amended 1990 and 1994. Particular attention shall be paid to safeaccess/egress from places of work and provision of a safe place of Design Life of InstallationUnless otherwise specified by NGC, the substation installation including busbars, connections, insulatorsand structures shall be designed for a life of 40 years subject to periodic preventive maintenance beingcarried out in accordance with manufacturers or suppliers instructions.

6 Where part of the installation would require replacement or mid-life refurbishment to achieve the specifieddesign life then this shall be stated at the time of tendering. Tenderers shall declare the life cycle costs ofequipment on request. Outage ConstraintsUnless otherwise specified or agreed by NGC the design of the substation shall permit installation,extension, operation and maintenance (preventive and corrective) with a maximum of one circuit and onebusbar section out of service simultaneously. A busbar section is taken to be a part of either the main orreserve busbars. Associated busbar section and busbar coupler circuits may be considered to be part ofthe busbar shall be advised at the Tender stage of any areas in which the requirements of this clause cannot line conductors of different outgoing circuits shall not be crossed unless otherwise agreed by Switchgear Local ControlThe installation of switchgear shall comply with the requirements of Clause of ngts ngts 3 Issue 2 May Operational AccessReasonable access shall be provided to the isolation facilities of each disconnector and earthing switch,including the locking device, where fitted.

7 Access shall comply with Clause and shall be suitable foruse by an unaccompanied person. Unless otherwise agreed with NGC the isolation facilities or locking devices shall be between 1 m and above the floor level or platform provided for access and shall not be further than 750 mm horizontallyfrom the edge of a above ground level shall be from mobile or fixed platforms (though the latter may be accessed byladder). Where movement of equipment within the substation would be restricted by the presence of laddersit is acceptable that these should be removable. Removable ladders and mobile platforms shall be easilyhandled and used on the finished substation surface by one and permanent platforms shall, where applicable, comply with BS 5395: Part 3.

8 Other Standardsmay be acceptable by agreement with NGC. Requirements for Maintenance The substation layout shall make allowance for preventive or corrective maintenance within the outageconstraints specified in Clause and using procedures compliant with Clause for maintenance shall be provided as follows:(i) The substation layout and surfaces shall be adequate to allow the access and use of powered accessequipment, cranes and similar equipment required for any normal maintenance operation (circuit-breakerinterrupter change, disconnector contact change, insulator cleaning etc). Suitable sealed surface roadsshall be provided to substation main buildings and heavy items of plant (eg transformers), other surfacesshould be finished in accordance with ngts (ii) Fixed platforms need not be provided for preventive or corrective maintenance requirements so long asaccess can be gained by the use of pre-formed scaffolding, portable ladders or, in outdoor Substations ,powered access of any fixed platforms provided shall be to the approval of NGC and shall meet therequirements of BS 5395: Part 3.

9 Other Standards may be acceptable by agreement with shall be taken to include the replacement of any component or sub-component within thesubstation including GIS shall, on request, provide a written procedure for carrying out any proposed maintenanceprocedure in accordance with these InterlockingSubstations shall be provided with a full interlocking scheme as specified in ngts of electronic interlocking schemes provided as part of substation control systems arespecified in ngts Cranes & Lifting EquipmentFixed cranes should not be provided in indoor AIS Substations except where specifically required formaintenance or repair purposes. Fixed cranes shall be provided in indoor GIS Substations except wherethe supplier can demonstrate specifically that they are not required for dismantling or removing any part ofthe substation for maintenance or repair 4 Issue 2 May 1995 Lifting beams or overhead cranes of adequate capacity shall be provided, where necessary, to assist indismantling switchgear.

10 Provision shall be made to inspect beams or cranes for insurance purposes andfit lifting tackle within the outage constraints specified in Clause FacilitiesThe following facilities shall be provided at all new 400 kV and 275 kV Substations .(i) Adequate toilet and washing facilities for NGC operation and maintenance staff.(ii) A standby control room, this shall have provision to be equipped as a permit office and to be used foron-site drawing/record storage. At indoor GIS Substations access to the control room shall not be throughthe switchgear hall and the room shall be designed to prevent ingress of SF6/arc products in the event ofa switchgear fault.(iii) At sites where SF6 gas-filled equipment is installed, a standing area and suitable water and drainageconnections for a mobile changing/shower facility.