Measured input
The function block uses analog current measurement values. The user can select the monitored
magnitude to be equal either to RMS values, to TRMS values, or to peak-to-peak values. TRMS mode
uses values from the whole harmonic spectrum of 32 components. Peak-to-peak mode picks
measurement values directly from the samples. A -20 ms averaged value of the selected magnitude is
used for pre-fault data registering.
Table. 5.4.3 - 57. Measurement inputs of the I0> function.
Signal
Description
Time base
I01RMS
RMS measurement of coarse residual current measurement input I01
5 ms
I01TRMS
TRMS measurement of coarse residual current measurement input I01
5 ms
I01PP
Peak-to-peak measurement of coarse residual current measurement input I01
5 ms
I02RMS
RMS measurement of sensitive residual current measurement input I02
5 ms
I02TRMS
TRMS measurement of coarse sensitive current measurement input I02
5 ms
I02PP
Peak-to-peak measurement of sensitive residual current measurement input I02
5 ms
I0Calc
RMS value of the calculated zero sequence current from the three phase currents
5 ms
The selection of the used AI channel is made with a setting parameter. 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. 5.4.3 - 58. General settings of the function.
Name
Range
Default
Description
Setting control
from comm bus
1:
Disabled
2:
Allowed
1:
Disabled
Activating this parameter permits changing the pick-up level of the protection stage
via SCADA.
I0> LN mode
1: On
2:
Blocked
3: Test
4: Test/
Blocked
5: Off
1: On
Set mode of NEF block.
This parameter is visible only when Allow setting of individual LN mode is enabled in
General menu.
Measured
magnitude
1: RMS
2: TRMS
3: Peak-
to-peak
1: RMS
Defines which available measured magnitude is used by the function. This
parameter is available when "Input selection" has been set to "I01" or "I02".
Measurement
side
1: Side
1
2: Side
2
1: Side
1
Defines which current measurement module is used by the function.
Input selection
1: I01
2: I02
3:
I0Calc
1: I01
Defines which measured residual current is used by the function.
A
AQ
Q-M257
-M257
Instruction manual
Version: 2.07
72
© Arcteq Relays Ltd
IM00021
Summary of Contents for AQ-M257
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