Mounting and Commissioning
3.3 Commissioning
SIPROTEC, 7UM62, Manual
C53000-G1176-C149-7, Release date 03.2010
412
DANGER!
In the generator, voltage hazardous to the stator winding can be caused by external 20 Hz bias voltage, even
at standstill.
Non-observance of the following procedures will result in death, serious injury or substantial property damage,
since 1% to 3% of the primary rated voltage of the generator being protected may be present.
The external 20 Hz bias voltage of the stator winding must be disconnected before doing work on the generator
at standstill.
Proceed as follows:
• Under fault-free conditions (R
E
infinite), the measured angle must be negative due to the capacitive earth
current. If it is not, the connection at the current input must be rotated. The phase angle „ϕ SEF=“ should
be about –90° due to the existing stator capacitances. If it is not, the value to complement it to –90° must be
determined and set as PHI I SEF = –90° – ϕ SEF. For a display value of e.g. „ϕ SEF=“ –75°, under
address 5309 PHI I SEF = –15° is set. This will change the measured value to approx. –90°.
In fault-free condition, the value displayed for R SEF must be in fault-free condition the maximum possible
value of 9999 Ω. The maximum value for the primary earth resistance R SEFp depends on the selected con-
version factor (FACTOR R SEF address 275).
• A short-circuit (R
E
= 0 Ω) is created in the generator starpoint, and the measured fault resistance (address
„R SEF=“) read out from the operational measured values. This resistance is set at address 5310 SEF
Rps.
• Insert now on the primary side a resistance which corresponds to the tripping value (e.g. 2 kΩ). Check the
measured fault resistance („R SEF=“). If this resistance differs very much from the value expected, modify
SEF Rps accordingly and, if necessary, make a fine adjustment with the correction angle (PHI I SEF).
Read out finally the fault resistance, and set this value as the tripping threshold at address 5303 R<< SEF
TRIP.
Next, insert a fault resistance for the alarm stage (e.g. 5 kΩ) on the primary side, and read out the fault re-
sistance („R SEF=“) from the operational measured values. This value is set at address 5302 as R< SEF
ALARM.
• Switch off the voltage supply for the 20 Hz generator, or block the binary input. The indication „SEF100
Failure“ will appear (not allocated on delivery). This ensures that a failure of the 20 Hz generator is reli-
ably detected. If this indication occurs already with the 20 Hz generator in operation, the monitoring thresh-
old (address 5307 U20 MIN) should be reduced. This can be the case if the loading resistances are very
small (< 1 Ω).
• Finally, a series of measurements is performed, starting with 0 kΩ and proceeding in steps of 1 kΩ. If
changes are made to the correction angle (PHI I SEF address 5309) or to the contact resistance (SEF
Rps, address 5310), the settings for the trip stage (R<< SEF TRIP) and the alarm stage (R< SEF ALARM)
must be matched as required.
• Now the earth resistance is reduced to about 90 % of the resistance for the alarm stage (address 5302 R<
SEF ALARM). After the delay time T SEF ALARM (10.00 s on delivery), set at address 5303, the stator earth
fault protection issues an alarm „SEF100 Alarm“ (not allocated on delivery).
Further reduce the earth resistance to 90 % of what the trip stage pickup value would be for the protection
device side (R< SEF ALARM, address 5303). The protection issues a pickup indication and after T SEF
TRIP address 5305 ( on delivery), a trip indication.
Remove the test resistor.
To Next Page
Loading...
