REG 316*4 1MRB520049-Uen / Rev. F ABB Switzerland Ltd
3-77
Typical settings:
Current 1.5 I
N
Delay 3 s
Hold-Voltage 0.7 U
N
Hold-Time 0.5 s
Should the rated currents of generator and c.t’s differ apprecia-
bly, compensation of the overcurrent setting is recommended, if
this has not already been done with the aid of the reference
value of the A/D channel.
Example:
Generator rated current I
GN
= 4 000 A
C.t. rated current I
N1
= 5 000 A
Typical value 1.5
(referred to the rated
current of the protection)
Compensated setting:
15 15
4000
5000
12
1
.. .
I
I
GN
N
==
since the rated voltages of generator and v.t’s are generally the
same, compensation of the undervoltage setting is seldom
necessary.
Should they differ, the compensated setting would be:
07
1
.
U
U
GN
N
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