3.3 Commissioning
279
7UM61 Manual
C53000-G1176-C127-3
Checking for Gen-
erator Earth Fault
Switch stator earth fault protection S/E/F PROT. (address 5001) to Block relay.
If the sensitive earth fault detection is used for stator earth fault protection, switch it to
Block relay also under address 5101. With the primary equipment disconnected
and earthed, insert a single-pole earth fault bridge in the generator terminal circuit.
DANGER!
Energized equipment of the power system ! Capacitive coupled voltages at discon-
nected equipment of the power system !
Non-observance of the following measure will result in death, severe personal injury
or substantial property damage.
Primary measurements must only be carried out on disconnected and grounded
equipment of the power system !
Start up generator and slowly excite to about 20 % U
N
.
Read out U
E
from the operational measured values and check for plausibility.
If the plant has more voltage transformers with broken delta windings, the voltage U
E
must be measured on them as well.
For protection zone Z the following applies:
Example:
Machine voltage at pick-up 0.1 x U
sec N
Read out the indication “U Earth Lx” in the fault log buffer. "Lx" indicates the faulted
phase provided voltages are connected to the voltage inputs of the device.
Shut down generator. Remove earth fault bridge.
Measured value U
E
= 10 V
Setting value U0> = 10 V
Protected zone Z = 90 %
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