The function outputs the START, TRIP and BLOCKED signals which can be used for direct I/O
controlling and user logic programming. The function generates general time-stamped ON/OFF events
to the common event buffer from each of the three (3) output signals. In the instant operating mode the
function outputs START and TRIP events simultaneously with an equivalent time stamp. The time stamp
resolution is 1 ms. The function also provides a resettable cumulative counter for the START, TRIP and
BLOCKED events.
The following figure presents a simplified function block diagram of the undercurrent function.
Figure. 5.4.20 - 106. Simplified function block diagram of the I< function.
Measured input
The function block uses analog current measurement values and uses RMS phase
current measurements. A -20 ms averaged value of the selected magnitude is used for pre-fault data
registering.
Table. 5.4.20 - 170. Measurement inputs of the I< function.
Signal
Description
Time base
IL1RMS
RMS measurement of phase L1 (A) current
5ms
IL2RMS
RMS measurement of phase L2 (B) current
5ms
IL3RMS
RMS measurement of phase L3 (C) current
5ms
In all possible input channel variations the pre-fault condition is presented with a 20 ms averaged
history value from -20 ms from a START or TRIP event.
General settings
The following general settings define the general behavior of the function. These settings are static i.e.
it is not possible to change them by editing the setting group.
Table. 5.4.20 - 171. General settings of the function.
Name
Range
Step Default
Description
I< LN mode
1: On
2: Blocked
3: Test
4: Test/
Blocked
5: Off
-
0: On
Set mode of NUC block.
This parameter is visible only when
Allow setting of individual LN mode is
enabled in
General menu.
A
AQ
Q-M257
-M257
Instruction manual
Version: 2.07
© Arcteq Relays Ltd
IM00021
207
Summary of Contents for AQ-M257
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