ABB Relion REB500, Commissioning Manual

Page: 22 / 26

Section 2
1MRK 505 351-UEN
Commissioning
14 Commissioning Manual
Distributed busbar protection REB500
In order to carry out the test, all the amplitudes and directions of the primary
currents must be known. Perform one of the following:
a) Short-circuit the CTs and isolate them from the protection.
b) Use the test mode to simulate that all the isolators are open (this is the
simpler method).
In the case of a), connect the infeeds one by one, or in the case of b), simulate the
closure of the isolators one by one. Whichever method is chosen, check that the
differential current increases as each infeed is connected (either HMI500 or the
local HMI in the central unit). Repeat this procedure with the loads and the
differential current must reduce as each feeder is connected.
In the case of systems, that evaluate the neutral current , the
differential current of the neutral measurement must be checked as
well. A neutral current has to be simulated in a symmetrical power
system in order to perform the stability test.
Figure 4 Testing the through-fault stability of the neutral circuit.
Any other protection devices in the same CT secondary circuit must not be
influenced in any way (e.g. transformer differential protection or ground fault
relays).