Figure. 5.4.12. - 75. Selectable measurement magnitudes with 2LL+U4 VT connection. If no residual voltage is connected
phase-to-earth voltages are not available.
P-P Voltages and P-E Voltages selections follow phase-to-neutral or phase-to-phase voltages in the
rst three voltage channels (or two rst voltage channels in 2LL+U3+U4 mode). U4 selection follows
voltage in channel 4. U3Input selection follows only the voltage in channel 3 if 2LL+U3+U4 mode is in
use.
Pick-up characteristics
Pick-up of the UV function is controlled by Uset setting parameter, which de nes the minimum allowed
measured voltage before action from the function. The function constantly calculates the ratio in
between of the Uset and measured magnitude (Um) per all three voltages. Reset ratio of 103 % is
inbuilt in the function and is always related to the Uset value. The setting value is common for all
measured amplitudes and single-, dual- or each voltage Um decrease below the Uset value will cause
pick-up operation of the function.
Table. 5.4.12. - 119. Pick-up characteristics setting
Name
Description
Range
Step
Default
Uset
Pick-up setting
0.00 …
120.00%Un
0.01%Un 60%Un
U Block
setting
Block setting. If set to zero blocking is not in use. Operation explained
in the next chapter.
0.00 …
100.00%Un
0.01%Un 10%Un
The pick-up activation of the function is not directly equal to start-signal generation of the function.
Start signal is allowed if blocking condition is not active.
Using block setting to prevent nuisance trips
To prevent the relay from tripping in a situation where the network is de-energized it is advised to use
the Block setting parameter. When the measured voltage drops below the set value relay will not give a
tripping signal. If the measured voltage has dropped below the Block setting the blocking will persist
until all of the line voltages have risen over the U< pick-up setting. Please see the image for a
visualization of this function.
AQ-F255
Instruction manual
Version: 2.00
© Arcteq Relays Ltd
130
