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Name
Range
Step
Description
I
meas
/I
set
Alarm
at the moment
0.00...1250.00
0.01
The ratio between the highest measured current unbalance and the pick-
up value.
Expected
operating time
-1800.000...1800.000s 0.005s
Displays the expected operating time when a fault occurs. When IDMT
mode is used, the expected operating time depends on the current
unbalance. If the measured current changes during a fault, the expected
operating time changes accordingly.
Time remaining
to trip
0.000...1800.000s
0.005s When the function has detected a fault and counts down time towards a
trip, this displays how much time is left before tripping occurs.
I
meas
/I
set
Trip
at the moment
0.00...1250.00
0.01
The ratio between the current unbalance and the pick-up value.
Function blocking
The block signal is checked in the beginning of each program cycle. The blocking signal is received
from the blocking matrix in the function's dedicated input. Additionally, the capacitor bank neutral
unbalance function includes an internal inrush harmonic blocking option which is applied according to
the parameters set by the user. 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.
Table. 5.3.2.2 - 57. Internal inrush harmonic blocking settings.
Name
Range
Step
Default
Description
Inrush harmonic blocking (internal-
only trip)
0: No
1: Yes
-
0: No
Enables and disables the 2
nd
harmonic
blocking.
2
nd
harmonic block limit (Iharm/
Ifund)
0.10…50.00%I
fund
0.01%I
fund
0.01%I
fund
Defines the limit of the 2
nd
harmonic
blocking.
If the blocking signal is active when the pick-up element activates, a BLOCKED signal is generated and
the function does not process the situation further. If the START function has been activated before the
blocking signal, it resets and the release time characteristics are processed similarly to when the pick-
up signal is reset.
The blocking of the function causes an HMI display event and a-time stamped blocking event with
information of the startup current values and its fault type to be issued.
The blocking signal can also be tested in the commissioning phase by a software switch signal when
the relay's testing mode "Enable stage forcing" is activated (
General
→
Device).
The variables the user can set are binary signals from the system. The blocking signal needs to reach
the device minimum of 5 ms before the set operating delay has passed in order for the blocking to
activate in time.
Operating time characteristics for reset
This function supports definite time delay (DT) time characteristics for alarm and trip time counters. For
detailed information on the programmable reset behavior of the function please refer to the chapter
"General properties of a protection function" and its section "Operating time characteristics for trip and
reset".
A
AQ
Q-C255
-C255
Instruction manual
Version: 2.06
© Arcteq Relays Ltd
IM00035
73