NG TS 3.06.16 PDF

This Specification describes the functional and performance requirements for the protection of 400 and 275 kV oil-immersed supergrid double-wound transformers constructed in accordance with IEC 76 or equivalent. It does not include single phase transformers for railway traction supplies, for which reference should be made to Engineering and Technology.

There may be some installations such as supplies to steelworks or rolling mills where the load contains an excessive harmonic content which could adversely affect the performance of biased differential relays, (Refer to Appendix A). For such installations, additional information may be required and this will be specified in the contract.

The detailed requirements for backup protection of double wound transformers are specified in NGTS 3.6.7 Backup Protection.

The requirements of devices for mechanical protection including gas and oil actuated relays, and oil and winding temperature instruments are specified in NGTS 2.3 Transformers and Reactors. This Specification describes their function within the transformer electrical protection system.

The requirements for the protection of HV and LV connections associated with the double wound transformer are specified in NGTS 3.6.14 Copperwork Protection.

The requirements for the trip relay resetting scheme are specified in NGTS 3.6.15 Trip Relays and Trip Relay Resetting.