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VAMP Ltd
Generator protection relay
Technical description
VAMP 210
VM210.EN004
Vamp 24h support phone: +358 (0)20 753 3264
23
SCntr NA
Cumulative
start
counter
TCntr
NA
Cumulative trip counter
Flt
%
Max. fault value
Recorded
values
EDly %
Elapsed time as compared to the
set operating time, 100% =
tripping
2.2.8.
Undervoltage protection (27/60)
The three-phase undervoltage protection comprises two stages,
U
1
< and U
1
<<, with separately adjustable operating times.
The function is based on measuring the fundamental frequency
component of the positive phase sequence voltage, which makes
the protection insensitive to unsymmetrical undervoltages
caused by earth-faults.
The operation of the undervoltage stage can be blocked with an
external control signal obtained via one of the digital inputs,
e.g. in a situation where the secondary voltage of the
measuring transformer disappears. Internal blocking is
possible in two special cases:
•
When the positive sequence voltage U1 suddenly drops
below block limit value. This is considered as “voltage
off” situation, not as an “under voltage”. The limit
setting is common for both stages.
•
When current is less then 1% of the generator nominal
current the stage can be blocked for a given time. This
setting is common for both stages.
&
t
&
&
alijsuoja2
MAX
>
t
s
t
r
Block
Setting
U<s
Delay
Start
Trip
Enable events
Register
event
Register
event
Figure 2.2.8-1 Undervoltage protection