NR NR/L2/SIGELP/30007 ISSUE 3 PDF

This specification defines the performance requirements for Class I and Class II hybrid, signalling FSP and intermediate transformers with a power rating of up to and including 10kVA. Unless otherwise stated, the requirements are required to be considered common to both Class I and Class II hybrid transformers.

The requirement for Class II hybrid transformers, where it is specified, is with respect to the primary winding only. There is no requirement for the secondary winding to be Class II.

Signalling FSP isolating transformers may be housed either in signalling equipment apparatus cases, relocatable equipment buildings or control centres, or co-located in electrical and plant apparatus cases.

NOTE: The size of Class I and Class II hybrid signalling FSP isolating transformers has been limited to ensure that system leakage currents are not exceeded. This limits the number of circuits to ensure distributed cable capacitance does not exceed limits that will affect insulation monitors and/or give rise to electric shock under earth fault conditions.