Functionality

Differential protection

High impedance differential protection(PDIF, 87)

The high impedance differential protection can be used when the involved CT cores have same turn

ratio and similar magnetizing characteristic. It utilizes an external summation of the phases and neu

tral current and a series resistor and a voltage dependent resistor externally to the relay.

The function can be set to be directional or non-directional independently for each of the steps.

Instantaneous residual overcurrent protection (PIOC, 50N)

The single input overcurrent function has a low transient overreach and short tripping times to

allow use as a high set short circuit protection function, with the reach limited to less than typical

eighty percent of the power line at minimum source impedance. The function can be configured

to measure the residual current from the three phase current inputs or the current from a separate

current input.

Four step residual overcurrent protection (PEFM, 51N/67N)

The four step single input overcurrent function has an inverse or definite time delay independent for

each step separately.

All IEC and ANSI time delayed characteristics are available together with an optional user

defined characteristic.