scope:

PURPOSE AND SCOPE

Informative: Throughout this document reference is made to National Gird Specifications. For the avoidance of doubt all references within this document to Technical Specifications (TS) can be taken to mean either National Grid Technical Specification (NGTS) or Technical Specification (TS) as appropriate.

This is a functional specification for switching boxes used at National Grid owned substations. The switching box shall provide a standard interface between the primary HV equipment and the secondary protection and control systems, to enable isolation for maintenance, testing and secondary equipment replacement.

The unit shall enable future replacement to be undertaken by the disconnection of existing equipment and reconnection of new equipment that has been thoroughly tested offline on a bay or modular basis. The reduction in site installation and commissioning will minimise the primary access requirements.

The protection and control system can be hardwired for legacy systems or an IEC61850 merging unit. It provides safety and operational isolation for both the HV equipment and the protection system.

The switching box shall be capable of reliable operation for the lifetime of the primary equipment..