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Voltage Transformer
Supervision
Table 4.10 – Measured and recorded values of CT supervisor: CTSV ( )
Parameter
Measured
ILmax
value
ILmin
Display
Imax>,
Imin<
Recorded
Date
Values
Time
Imax
Imin
The device supervises the VTs and VT wiring between the
device terminals and the VTs. If there is a fuse in the voltage
transformer circuitry, the blown fuse prevents or distorts the
voltage measurement. Therefore, an alarm should be issued.
Furthermore, in some applications, protection functions using
voltage signals should be blocked to avoid false tripping.
The VT supervisor function measures the three phase voltages
and currents. The negative sequence voltage U
sequence currentI
are calculated. If U
2
and at the same time, I
2
will issue an alarm after the operation delay has elapsed.
Table 4.11 – Setting Parameters of VT Supervisor: VTSV ( )
Parameter
Value
U2>
0.0 ... 200.0
I2<
0.0 ... 200.0
t>
0.02 ... 600.0
VT on
On; Off
VT off
On; Off
Table 4.12 – Measured and Recorded Values of VT Supervisor: VTSV ( )
Parameter
Measured
U2
value
I2
Recorded
Date
Values
Time
U2
I2
Supporting Functions
Value
Unit
A
Maximum of phase currents
A
Minimum of phase currents
A
Setting values as primary values
-
Date of CT supervision alarm
-
Time of CT supervision alarm
A
Maximum phase current
A
Minimum phase current
2
exceed the U
2
is less than the I
< setting, the function
2
Unit
Default
%Un
34.6
Upper setting for VT supervisor
%In
100.0
Lower setting for VT supervisor
s
0.10
Operation delay
-
On
VT supervisor on event
-
On
VT supervisor off event
Value
Unit
%Un
Measured negative sequence
voltage
%In
Measured negative sequence
current
-
Date of VT supervision alarm
-
Time of VT supervision alarm
%Un
Recorded negative sequence
voltage
%In
Recorded negative sequence
current
4-11
Description
and the negative
> setting
2
Description
Description
857-UM001A-EN-P – July 2009
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