3.3 Commissioning
287
7UM61 Manual
C53000-G1176-C127-3
• Reduce excitation slowly to approximately 30% rated apparent power of generator
(underexcited).
– Read out the motoring power P
2
with polarity (negative) in the operational mea-
sured values and note it (see table below).
– Read out reactive power Q
2
with polarity (negative) in the operational measured
values and note it (see table below).
• Adjust generator to no-load excitation and shut it down or select the desired opera-
tional state.
Figure 3-22
Determination of the Correction Angle W0
The read-out measured values P
1
, and P
2
are now used to carry out CT angle error
correction. First calculate a correction angle from the measured value pairs according
to the following formula:
The power values must be inserted with their correct polarity as read out! Oth-
erwise faulty result!
This angle
ϕ
corr
is entered
with reversed sign
as the new correction angle under
address
204
CT ANGLE W0
:
Setting value
CT ANGLE W0
= –
ϕ
corr
A quarter of the sum of the measured values P
1
+ P
2
is set as pickup value of the
reverse power protection
P> REVERSE
under address
3102
.
Calibrating the
Reverse Power Pro-
tection
If a generator is connected with the network, reverse power can be caused by
• closing of the regulating valves,
• closing of the trip valve
Because of possible leakages in the valves, the reverse power test should – if possible
– be performed for both cases.
In order to confirm the correct settings, repeat the reverse power measurement again.
For this, the reverse power protection (address
3101
) is set to
Block relay
in order
to check its effectiveness (using the indications).
Start up generator and synchronize with network. Close regulating valves.
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