Application Guide - NP900 Series
174 (504
)
A996A
3.2.16.5
U
SING
B
LOCK SETTING TO PREVENT NUISANCE TRIPS
In case “Under <” is the chosen tripping condition to prevent the relay from tripping in a
situation where the network is de-energized it is advised to use the
Under block setting
Ublk
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
Under block setting Ublk
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. If block level is set to zero,
blocking is not in use.
Figure 3.2.16.5-89 Block setting operation example. If Block setting is set to zero blocking
is not in use.
3.2.16.6
R
EAL
-
TIME INFO DISPLAYED OF 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 SMART9 software when connection
there is a connection to relay and Live Edit-mode is activated.
Name
Unit
Description
U1/2 >/< 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.
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.
