Settings Of The 100-% Stator Earth Fault Protection - Siemens Siprotec 7UM62 Manual

Correction Angle,
Contact Resistance

2.29.2.1 Settings of the 100-% Stator Earth Fault Protection

Addr. Setting Title
5301 100% SEF-PROT.
5302 R< SEF ALARM
5303 R<< SEF TRIP
5304 T SEF ALARM
5305 T SEF TRIP
5306 SEF I>>
5307 U20 MIN
5308 I20 MIN
5309 PHI I SEF
5310A SEF Rps
5311A Rl-PARALLEL
7UM62 Manual
C53000-G1176-C149-3
100–% Stator Earth Fault Protection with 20 Hz Voltage Injection (ANSI 64G - 100%)
The parameter PHI I SEF (default setting 0°) of address 5309 is used to compen-
sate the angle error of the CTs and angle distortions caused by a less than ideal earth-
ing or neutral transformer. The correct setting for this parameter can only be deter-
mined with a primary test. The adjustment should be made for the tripping value.
The same is true for the transfer resistance of the earthing or neutral transformer. This
advanced parameter can be set with the DIGSI communication software (not possible
in local operation). As this resistance is normally negligible, a default setting SEF Rps
= 0 Ω has been chosen for address 5310A. However, the transfer resistance of the
voltage transformer is no longer negligible if the 20 Hz voltage is fed to a primary-side
loading resistor via a voltage transformer.
In large power units with generator circuit breaker, applications can be found where
there is some additional loading equipment on the low-voltage side of the unit trans-
former to reduce the influence by the zero voltage when the generator circuit breaker
is open. The 20 Hz source is connected via the neutral transformer in the generator
starpoint. With the generator circuit breaker closed, the protection measures the load-
ing resistance on the unit transformer side, which can be mistaken for an earth resis-
tance. The advanced parameter address 5311A allows to set this additional loading
resistance. The default setting for Rl-PARALLEL is ∞. No additional loading resis-
tance is assumed.
Setting Options
OFF
ON
Block relay for trip com-
mands
20..700 Ohm
20..700 Ohm
0.00..60.00 sec; ∞
0.00..60.00 sec; ∞
0.02..1.50 A
0.3..15.0 V
5..40 mA
-60..60 °
0.0..700.0 Ohm
20..700 Ohm; ∞
Default Setting
OFF 100% Stator-Earth-Fault Protec-
tion
100 Ohm Pickup Value of Alarm Stage
Rsef<
20 Ohm Pickup Value of Tripping Stage
Rsef<<
10.00 sec Time Delay of Alarm Stage
Rsef<
1.00 sec Time Delay of Tripping Stage
Rsef<<
0.40 A Pickup Value of I SEF>> Stage
1.0 V Supervision Threshold of 20Hz
Voltage
10 mA Supervision Threshold of 20Hz
Current
0 °
Correction Angle for I SEF 100%
0.0 Ohm Resistance Rps
∞ Ohm
Parallel Load Resistance
Comments
199