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.
Figure. 5.4.10. - 54. Block setting operation example. If Block setting is set to zero blocking is not in use.
Real-time info displayed by the function
The relays Info-page displays useful information in real time of the state of the protection function either
through relays HMI display or with AQtivate software when connection there is a connection to relay
and Live Edit-mode is activated.
Name
Unit
Description
U< Pick-up
setting
V
Primary voltage required for tripping. The displayed pick-up voltage level depends on the pick-up
setting and the voltage transformer settings.
U< Block
setting
V
Primary voltage level for trip blocking. If measured voltage is below this value the network is
considered de-energized and function will not trip. To deactivate the blocking measured voltage
must go above pick-up setting.
Expected
operating
time
s
Displays the expected operating time in case a fault occurs
Time
remaining to
trip
s
When the relay has picked up and is counting time towards pick-up
Umeas/Uset
at the
moment
Um/Uset Ratio between measured voltage and the pick-up value.
AQ-T257
Instruction manual
Version: 2.00
105
© Arcteq Relays Ltd
