Functional Test for Overvoltage Protection with Zero-Sequence
Voltage/Residual Voltage
Checking the Stator Ground-Fault Protection with the Machine
You have to check whether the protection function and the protection ranges are functioning correctly. The
following tests are intended for the unit connection.
You can check the protection range by performing a test with a ground fault at the generator terminals. The
ground fault test in the power system enables you to verify the noise suppression of the load resistor.
Checking the Protection Range with a Machine Ground Fault
DANGER
Touching live parts or reaching into rotating machines will result in death or serious injury.
²
Perform primary measures only when the machine is at standstill and the system components are de-
energized and grounded.
²
Insert a 1-phase-to-ground jumper into the terminal circuit of the machine.
²
Set the Mode parameter in the protection stage to test. This prevents the trip command from being
generated for the stage.
²
Start the machine and excite it slowly up to approx. 20 % of the rated machine voltage.
²
From the operational measured values, check the plausibility of the zero-sequence voltage V
0
and the
input voltage at the connected input.
²
Determine the protection range from the pickup voltage.
The following applies for the protection range S:
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Example: Measurement with secondary voltages
V
NG
Generator voltage transformed to the transformer secondary side = 100 V
V
0, pickup value
: Measured zero-sequence voltage at pickup = 5.68 V
S: Resulting protection range = 90 %
²
Check the messages in the message buffer. If the Detection of faulty phase parameter is set to
yes, check the display of the phase affected by the fault.
²
Shut the machine down and remove the ground fault bridge.
²
Set the Mode protection stage parameter to on.
11.11
Functional Tests
11.11 Functional Test for Overvoltage Protection with Zero-Sequence Voltage/Residual Voltage
SIPROTEC 5, Overcurrent Protection, Manual 1389
C53000-G5040-C017-8, Edition 07.2017
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