Control pulses minimum and maximum times are user set. If during the control pulse tap changes and
the voltage changes as well to controlled direction the command is terminated. If the maximum set
control time has passed the control signal is terminated. In case of instant low request the minimum
time between pulses is used after the control pulse is terminated to prevent new control pulse output
during this time.
Tap settings
The properties of the used tap changer are set in Tap settings. Number of tap changer positions and
middle position as well as the position indication message is con gured here.
Example:
Transformer has tap changer with 18 positions of which position 9 presents middle position. Tap
changer location is indicated by mA signal 4…20 mA to the relay. Each tap position has 1.67% effect
to the transformer output voltage. The highest mA value is expected when tap is in the highest position.
Tap changer properties are set to the AVR:
Setting
Value
Tap position indication
mA input
Tap steps totally
18 steps
Tap center position
9 step
Tap step effect
1.67 %
mA input low range
4 mA
mA input high range
20 mA
Tap position indication
Max.mA.max.Pos
AVR function calculates based to given values:
Calculation
Value
Tap step voltage effect
334 Vpri
Tap maximum decrease
-15.03%
Tap maximum increase
15.03%
Tap control band
30.06%
Tap step in mA
0.889mA
mA input now
measured mA input value
These basic settings de ne the control area where AVR must operate.
AQ-T257
Instruction manual
Version: 2.00
© Arcteq Relays Ltd
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