VAMP 259 - Voltage Transformer Supervision

Technical description
3 Supporting functions
3.7 Voltage transformer supervision
VM259.EN007
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159
3.7. Voltage transformer supervision
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
2
and the
negative sequence currentI
2
are calculated. If U
2
exceed the
U
2
> setting and at the same time, I
2
is less than the I
2
< setting,
the function will issue an alarm after the operation delay has
elapsed.
Setting parameters of VT supervisor VTSV ( ):
Parameter
Value
Unit
Default
Description
U2>
0.0 … 200.0
%Un
34.6
Upper setting for VT
supervisor
I2<
0.0 … 200.0
%In
100.0
Lower setting for VT
supervisor
t>
0.02 … 600.0
s
0.10
Operation delay
VT on
On; Off
-
On
VT supervisor on event
VT off
On; Off
-
On
VT supervisor off event
Measured and recorded values of VT supervisor VTSV ( ):
Parameter
Value
Unit
Description
Measured
value
U2
%Un
Measured negative
sequence voltage
I2
%In
Measured negative
sequence current
Recorded
Values
Date
-
Date of VT supervision
alarm
Time
-
Time of VT supervision
alarm
U2
%Un
Recorded negative
sequence voltage
I2
%In
Recorded negative
sequence current