Figure. 5.3.3 - 87. Simplified function block diagram of the I0> fucntion.
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. 5.3.3 - 58. 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. 5.3.3 - 59. General settings of the function.
Name
Description
Range
Default
Setting control
from comm bus
Activating this parameter permits changing the pick-up level of the protection stage
via SCADA.
1:
Disabled
2:
Allowed
1:
Disabled
A
AQ
Q-F215
-F215
Instruction manual
Version: 2.04
109