Inputs for the function are the operating mode selections, setting parameters and measured and pre-
processed current magnitudes and binary input signals. Function outputs START, TRIP and BLOCKED
signals which can be used for direct IO controlling and also for user logic programming. The function
registers its operation into 12 last time-stamped registers and also generates general time stamped
ON/OFF events to the common event buffer from each of the three output signals. In instant operating
mode the function outputs START and TRIP events simultaneously with equivalent time stamp. Time
stamp resolution is 1ms. Function provides also cumulative counters for START, TRIP and BLOCKED
events.
In the following gure is presented the simpli ed function block diagram of the NEF function.
Measured input values
Function block uses analog current measurement values. Function block always utilizes peak-to-peak
measurement from samples and by user selection the monitored magnitude can be either fundamental
frequency RMS values, True RMS values from the whole harmonic specter of 32 components or peak
to peak values. -20ms averaged value of the selected magnitude is used for pre-fault data registering.
Table. 5.4.2. - 55. Analogic magnitudes used by the NEF function.
Signal
Description
Time base
I01PP
Peak-to-peak measurement of coarse residual current measurement input I01
5 ms
I01RMS
Fundamental RMS measurement of coarse residual current measurement input I01
5 ms
I01TRMS TRMS measurement of coarse residual current measurement input I01
5 ms
I02PP
Peak-to-peak measurement of sensitive residual current measurement input I02
5 ms
I02RMS
Fundamental RMS measurement of sensitive residual current measurement input I02
5 ms
I02TRMS TRMS measurement of coarse sensitive current measurement input I02
5 ms
I0Calc
Fundamental RMS value of the calculated zero sequence current from the three phase currents
5 ms
Selection of the used AI channel is made with a setting parameter. In all possible input channel
variations pre-fault condition is presented with 20 ms averaged history value from -20 ms of Start or
Trip event.
General settings
The following general settings de ne the general behavior of the function. These settings are static i.e.
it is not possible change them with setting group switching.
AQ-T257
Instruction manual
Version: 2.00
© Arcteq Relays Ltd
48