ABB Relion 670 Series Applications Manual page 279

1MRK 511 401-UEN Rev. K
Based on the number of operated fuses, the capacitance values in the system and the neutral
voltage unbalance are calculated as listed in
Table 48: Neutral unbalance voltage calculation for an internally fused ungrounded single WYE capacitor bank
No of
Fuses
operat
ed
(n)
0
1
2
3
4
5
6
7
8
9
If the failure of the elements or the units results in the neutral unbalance voltage of at least 1%
of UBase, the SCUVPTOV function detects the fault.
Table 49
Table 49: Settings of SCUVPTOV for an internally fused ungrounded single WYE capacitor bank
Name
BlockTrip
UMin>
CompEnable
UNUnbalWrn>
tDefWrn
UNUnbalAlm>
tDefAlm
UNUnbal>
CurveType
tDefTrip
tMin
tReset
k
tPCrv
tACrv
tBCrv
tCCrv
tDCrv
CrvSat
Bay control REC670
Application manual
with element failures
C C C
g s p
(pu) (pu) (pu)
1.000 1.000 1
0.997 0.998 0.995
0.993 0.996 0.989
0.988 0.994 0.981
0.981 0.991 0.972
0.974 0.987 0.960
0.963 0.981 0.943
0.948 0.973 0.920
0.926 0.962 0.885
0.889 0.941 0.824
lists the recommended settings for the SCUVPTOV function in this example.
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Table 48.
V %V C
NG NG LN
(pu) (pu)
0 0 1
0.0016 0.169 1.002
0.0037 0.375 1.004
0.0063 0.629 1.006
0.0095 0.952 1.010
0.0138 1.377 1.014
0.0196 1.961 1.020
0.0281 2.811 1.028
0.0417 4.167 1.042
0.0667 6.667 1.067
Default value
Trip enabled
75.0% of UBase
Enable
1.0% of UBase
5.00
2.0% of UBase
5.00
4.0% of UBase
Programmable
0.1
0.10
0.02
0.05
1.000
1.000
1.00
0.0
0.000
0.000
Section 10
Unbalance protection
V %V Event
CU CU
(pu)
1.000 100.0
1.003 100.3
1.007 100.7
1.013 101.3
1.019 101.9 Warning
1.027 102.7
1.039 103.9 Alarm
1.055 105.5
1.082 108.2 Trip
1.129 112.9
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