DOC. MIE91093 Rev. 1.34
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time and no trip. This limit can also be found starting the test
with V1=VN, and then lowering V1 until the relay trips.
If the starter is over-current, and it is desired to find threshold
settings IVN and IVo, the test is performed as a time
independent over-current relay, but test voltage will be 0 V for
the test of IVo, and VN for the test of IVN.
The test can continue as follows:
. Test the same settings, with faults on phases 2 and 3;
. Test other types of fault.
1.12.6 Phase to phase fault
In phase to phase faults, voltage and current vectors are
modified during the test as shown in the following figure,
which refers to the fault of phases 2 and 3.
Note that in this type of fault the fault voltage is the phase to
phase voltage; fault currents are identical in module and
opposite in phase; the fault current angle is metered with
respect to the phase to phase voltage.
This situation makes the test of phase to phase faults quite
cumbersome. For each test, it should be necessary to modify
the fault voltage amplitude and phase. However, it is possible
