ABB RELION 620 Series Technical Manual page 532

Hide thumbs Also See for RELION 620 Series:

Table of Contents

Protection-related functions

Operation principle

The function can be enabled and disabled with the Operation setting. The corresponding

parameter values are "Enable" and "Disable".

The operation of an inrush current detection function can be described using a module

diagram. All the modules in the diagram are explained in the next sections.

A070694 V2 EN

Functional module diagram. I_1H and I_2H represent fundamental and

second harmonic values of phase currents.

This module calculates the ratio of the second harmonic (I_2H) and fundamental

frequency (I_1H) phase currents. The calculated value is compared to the set Pickup

value. If the calculated value exceeds the set Pickup value, the module output is activated.

Level detector

The output of the phase specific level detector is activated when the fundamental

frequency current I_1H exceeds five percent of the nominal current.

Once activated, the timer runs until the set Trip delay time value. The time characteristic

is according to DT. When the trip timer has reached the Trip delay time value, the BLK2H

output is activated. After the timer has elapsed and the inrush situation still exists, the

BLK2H signal remains active until the I_2H/I_1H ratio drops below the value set for the

ratio in all phases, that is, until the inrush situation is over. If the drop-off situation occurs

1MAC504801-IB E

620 series ANSI

Technical Manual

Chapters

Table of Contents