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Definite time reset
A definite time reset characteristic is applied to the NOV1 element when the inverse time delay is
used. Its operation is identical to that for the phase overvoltage protection.
Scheme Logic
Figure 2.2.14 shows the scheme logic of the negative sequence overvoltage protection. Two
negative sequence overvoltage elements NOV1 and NOV2 with independent thresholds output
trip signals NOV1 TRIP and NOV2 TRIP through delayed pick-up timers TNOV1 and TNOV2.
The tripping can be disabled by the scheme switches [NOV1EN] and [NOV2EN] or PLC logic
signals NOV1 BLOCK and NOV2 BLOCK.
232, 1924
NOV1D
248, 1940
NOV1I
"DT"
[NOV1EN]
+
"IDMT"
1
1596
NOV1 BLOCK
233, 1925
NOV2
[ZOV2EN]
+
"ON"
1
1597
NOV2 BLOCK
Figure 2.2.14
Settings
The table below shows the setting elements necessary for the negative sequence overvoltage
protection and their setting ranges.
Element
Range
NOV1
5.0 - 130.0 V
NOV2
5.0 - 130.0 V
TNOV1P
0.05 – 100.00
TNOV1D
0.00 – 300.00 s
TNOV1R
0.0 – 300.0 s
TNOV2
0.00 – 300.00 s
[NOV1EN]
Off / DT/IDMT
[NOV2EN]
Off / On
The delay time setting TNOV1 and TNOV2 is added to the inherent delay of the measuring
elements NOV1 and NOV2. The minimum operating time of the NOV elements is around 200ms.
&
&
0.00 - 300.00s
&
&
679
≥1
680
&
&
0.00 - 300.00s
Negative Sequence Overvoltage Protection
Step
Default
0.1V
20.0 V
0.1V
40.0 V
0.01
1.00
0.01 s
1.00 s
0.1 s
0.0 s
0.01 s
1.00 s
Off
Off
⎯
⎯
86
TNOV1
0
t
476
≥ 1
NOV1 OP
TNOV2
477
t
0
Remarks
NOV1 threshold setting for tripping.
NOV2 threshold setting for alarming.
NOV1-I time multiplier setting.
Required if [NOV1EN]=IDMT.
NOV1-D definite time setting.
Required if [NOV1EN]=DT.
NOV1-I definite time delayed reset.
NOV2 definite time setting
NOV1 Enable
NOV2 Enable
6 F 2 S 0 8 4 2
NOV1 TRIP
NOV2 ALARM
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