3.3 Commissioning
411
7UT613/63x Manual
C53000-G1176-C160-2
The phase angles must be 180° in all cases.
Check the differential and restraint currents for each phase.
If single-phase primary checks cannot be carried out but only symmetrical operational
currents are available, polarity or connecting errors in the earth current path with sum-
mation transformer connection L1–L3–E will not be detected with the before-men-
tioned checks. In this case, asymmetry is to be achieved by secondary manipulation.
Therefore the current transformer of phase L2 is short-circuited as shown in figure
3-39.
DANGER!
Manipulations on the measuring current transformers must be performed with
the utmost precaution!
Non-observance of the following measures will result in death, severe personal injury
or substantial property damage.
Short-circuit the current transformers before disconnecting any current supply leads
to the device!
Figure 3-39 Asymmetrical test with summation transformer connection L1-L3-E
The measured current is now 2.65 times the current of the symmetrical test.
This test must be carried out for each summation CT.
3.3.11 Testing of the Non-Assigned 1-Phase Current Inputs
As far as single-phase current inputs belong to the main protected object, i.e. they are
assigned to a side of the main protected object, they were already checked with the
zero sequence current tests.
Even if they are not assigned to the main protected object but to a 3-phase measuring
location of a further protected object (e.g. restricted earth fault protection for a sepa-
rate neutral earthing reactor), the same procedure as for the zero sequence current
applies. Perform the zero sequence current tests unless it has already been done.
Single-phase measured current inputs of the device can also be used for any desired
1-phase protection function. If this is an actual case and the same input has not yet
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