ABB Switzerland Ltd REG 316*4 1MRB520049-Uen / Rev. F
3-234
E. Setting instructions
The value of ‘RF-Setting’ for alarm must always be higher than
that of ‘RF-Setting’ for tripping.
Both alarm and tripping stages have their own timers.
Typical delays used for the 100 % ground fault protection are in
the range of seconds.
Settings:
‘RFs-Setting’ for tripping
‘RFs-Setting’ for alarm
Delay for tripping
Delay for alarm
Grounding resistor REs
Measuring transformer ratio (MTR).
Typical settings:
Alarm stage:
RFs-Setting 5 k
W
Delay 2 s
Tripping stage:
RFs-Setting 500
W
Delay 1 s
Setting procedure:
The accuracy of the Rfs calculation depends on the values en-
tered for REs and MTR. Therefore check the settings and correct
them if necessary by connecting resistors between 100
W and
10 k
W between the star-point 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 ‘AdjMTRInp’ or ‘AdjREsInp’. This is the recom-
mended procedure. In this mode, the settings of the parameters
‘MTR’ and ‘REs’ are calculated with the aid of simulated ground
fault resistances. The two parameters are displayed continuously
in the measured values window.
Should the values of REs and MTR determined by the adjust-
ment modes differ from their nominal values, the calculated val-
ues are the preferred values.
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