The 515 Blocking and Test Module provides an effective means of trip blocking, relay isolation and testing of Multilin relays.
By opening the switches and inserting test plugs,phase and residual currents from the pri-mary CTs can be monitored.
Currents can be injected into the relay from a secondary injection test set during commissioning.
Prior to withdrawal, the trip and auxiliary circuits must be opened first, to prevent nuisance tripping, and CT’s can then be shorted.
Conversely, when the test is done and the relay is put back in operation, the CT switches should be closed first to ensure normal operation of the relay, prior to clos-ing the trip and auxiliary circuits.