Siemens SIPROTEC 7UM62, Manual

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100–% Stator Earth Fault Protection with 20 Hz Voltage Injection (ANSI 64G - 100%)
199
7UM62 Manual
C53000-G1176-C149-3
Correction Angle,
Contact Resistance 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.
2.29.2.1 Settings of the 100-% Stator Earth Fault Protection
Addr. Setting Title Setting Options Default Setting Comments
5301 100% SEF-PROT. OFF
ON
Block relay for trip com-
mands OFF 100% Stator-Earth-Fault Protec-
tion
5302 R< SEF ALARM 20..700 Ohm 100 Ohm Pickup Value of Alarm Stage
Rsef<
5303 R<< SEF TRIP 20..700 Ohm 20 Ohm Pickup Value of Tripping Stage
Rsef<<
5304 T SEF ALARM 0.00..60.00 sec;
∞
10.00 sec Time Delay of Alarm Stage
Rsef<
5305 T SEF TRIP 0.00..60.00 sec;
∞
1.00 sec Time Delay of Tripping Stage
Rsef<<
5306 SEF I>> 0.02..1.50 A 0.40 A Pickup Value of I SEF>> Stage
5307 U20 MIN 0.3..15.0 V 1.0 V Supervision Threshold of 20Hz
Voltage
5308 I20 MIN 5..40 mA 10 mA Supervision Threshold of 20Hz
Current
5309 PHI I SEF -60..60
°
0
°
Correction Angle for I SEF 100%
5310A SEF Rps 0.0..700.0 Ohm 0.0 Ohm Resistance Rps
5311A Rl-PARALLEL 20..700 Ohm;
∞ ∞
Ohm Parallel Load Resistance