UK Power Networks
UKPN Innovation Team
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Innovation Funding Incentive
LV & 11kV Networks
There is a requirement to perform annual trip testing of all circuit breakers. Current practice for schemes involving IDMT protection involves initiating the trip by manual movement of the relay disc (for older electromechanical relays) and by various other means for electronic relays. Neither of these approaches proves the integrity of the protection and in the case of the first method is actually undesirable due to physical intervention of the relay.
It is possible to perform this test by secondary injection of the relay, but existing equipment can only produce the desired trip, but gives no condition information about the relay timing.
Following discussions with Relay Engineering Services, they have suggested that it is possible to perform an annual test that tests the relay and its setting.
To perform this annual test by secondary injection of the relay and to accurately measure the current seen by the relay and time the overall trip operation thereby enabling an accurate operating time of the relay to be established.