Name
Range
Default
Description
Measured
magnitude
1: U1 Positive
sequence voltage
2: U2 Negative
sequence voltage
1: U1 Positive
sequence voltage
Selects which calculated voltage is supervised.
Pick-up
The
U
set
setting parameter controls the pick-up of the U1/U2>/< function. This defines the maximum or
minimum allowed calculated U1 or U2 voltage before action from the function. The function constantly
calculates the ratio between the
U
set
and the calculated U1 or U2 magnitude (
U
c
). The monitored
voltage is chosen in the
Info page with the parameter Measured magnitude. The reset ratio of 97 % in
overvoltage applications is built into the function and is always relative to the
U
set
value. The reset ratio
of 103 % in undervoltage applications is built into the function and is always relative to the
U
set
value.
When the
U
c
goes above or below the
U
set
value it triggers the pick-up operation of the function.
Table. 5.4.13 - 132. Pick-up settings.
Name
Description
Range
Step
Default
Pick-up
terms
Selects whether the function picks-up when the monitored voltage is
under or over the set pick-up value.
Over >
Under<
-
Over>
U
set
Pick-up setting
5.00…150.00%U
n
0.01%U
n
105%U
n
U
blk
Undervoltage blocking (visible when the pick-up term is Under<)
0.00…80.00%U
n
0.01%U
n
5%U
n
The pick-up activation of the function is not directly equal to the START signal generation of the
function. The START signal is allowed if the blocking condition is not active.
Using
Block setting to prevent nuisance trips
It is recommended to use the
Under block setting U
blk
parameter when Under< is the chosen tripping
condition to prevent the relay from tripping in a situation where the network is de-energized. When the
measured voltage drops below the set value, the relay does not give a tripping signal. If the measured
voltage has dropped below the
Under block setting U
blk
parameter, the blocking continues until all of
the line voltages have increased above the U< pick-up setting. Please see the image below for a
visualization of this function. If the block level is set to zero (0), blocking is not in use.
Figure. 5.4.13 - 85. Example of the block setting operation.
A
AQ
Q-M257
-M257
Instruction manual
Version: 2.07
© Arcteq Relays Ltd
IM00021
159
Summary of Contents for AQ-M257
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