Operation mode
Pick-up criteria selection
0: All faults
1: P-P faults
2: Only 3P faults
-
0:All faults
Uset
Pick-up setting
50.00 … 150.00%Un
0.1%Un
120%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.
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.
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.
Function blocking
In the blocking element the block signal is checked in the beginning of each program cycle. Blocking
signal is received from the blocking matrix for the function dedicated input. If the blocking signal is not
activated when the pick-up element activates, a START signal is generated and the function proceeds
to the time characteristics calculation.
If blocking signal is active when pick-up element activates a BLOCKED signal will be generated and the
function shall not process the situation further. If START function has been activated before blocking
signal it will reset and the release time characteristics are processed as in case of when pick-up signal
is reset.
From blocking of the function a HMI display event as well as time stamped blocking event with
information of the startup voltage values and fault type is issued.
Blocking signal can be tested also in the commissioning phase of the stage by software switch signal
when relay common and global testing mode is activated.
User settable variables are binary signals from the system. Blocking signal needs to reach the IED
minimum of 5 ms before the set operating delay has passedfor blocking to be active in time.
Operating time characteristics for trip and reset
The operating timers’ behavior of the function can be set for trip signal and also for the release of the
function in case the pick-up element is reset before the trip time has been reached. There are three
basic operating modes available for the function. Instant operation gives the trip signal with no
additional time delay simultaneously with start signal. De nite time operation (DT) will give trip signal
with user given time delay regardless of the measured voltage as long as the voltage is above the Uset
value and thus pick-up element is active (independent time characteristics). Inverse de nite minimum
time (IDMT) will give the trip signal in time which is in relation of the set pick-up voltage Uset and
measured voltage Um (dependent time characteristics). The IDMT function follows this formula:
AQ-T257
Instruction manual
Version: 2.00
99
© Arcteq Relays Ltd