IEC07000186 V1 EN
Figure 146: Simplified Start and Trip logical diagram of the STEFPHIZ protection
There are two different cases of generator block configuration; with or without
generator circuit breaker. If there is no generator breaker the capacitive coupling to
earth is the same under all operating conditions. When there is a generator breaker, the
capacitive coupling to earth differs between the operating conditions when the
generator is running with the generator breaker open (before synchronization) and
with the circuit breaker closed. This can be shown as in figure
147.
- DU
3
+
- U
3
+
- U
3N
+
+
U
3T,L1
-
+
U
3T,L2
-
+
U
3T,L3
-
en07000002-2.vsd
Ctr/3
Ctr/3
Ctr/3
IEC07000002 V2 EN
Figure 147: Generator block with generator circuit breaker
With the circuit breaker open, the total capacitance will be smaller compared to
normal operating conditions. This means that the neutral point 3
rd
harmonic voltage
will be reduced compared to the normal operating condition. Therefore, there is a
Section 9 1MRK 502 048-UEN A
Voltage protection
292
Technical manual
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