REG 316*4 1MRB520049-Uen / Rev. F ABB Switzerland Ltd
3-255
E. Setting instructions
The value of ‘RF
r
-Setting’ for alarm must always be higher than
that of ‘RF
r
-Setting’ for tripping. Both alarm and tripping stages
have their own timers. Typical delays used for the rotor ground
fault protection are in the range of seconds.
Recommended resistances:
R
Er
= 1000 W
R
Pr
= 100 W.
Settings:
Grounding resistor REr
Coupling capacitor C
‘RFr-Setting’ for tripping
‘RFr-Setting’ for alarm
Delay for alarm
Delay for tripping.
Typical settings:
Alarm stage:
RFr-Setting 5 k
W
Delay 2 s
Tripping stage:
RFr-Setting 500
W
Delay 1 s.
Setting procedure:
How accurately Rfr is measured depends on the values entered
for REr and C. Therefore check the settings and correct them if
necessary by connecting resistors between 100
W and 10 kW
between the rotor and ground while the generator is not running.
The protection function provides a convenient way of setting
these two parameters in the software by switching its mode us-
ing the input ‘AdjRErInp’ or ‘AdjCoupCInp’. In this mode, the set-
tings of the parameters ‘REr’ and ‘C’ are calculated with the aid
of simulated ground fault resistances.
Determination of REr
· Apply a logical ‘1’ to the binary input ‘AdjRErInp’.
· Short-circuit the coupling capacitors.
· Simulate a ground fault Rf by connecting a resistor to the
rotor: 8 k
W < Rf < 12 kW
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