Operation Principle; Measurement Modes; Timer Characteristics; Application - ABB RELION 620 Series Technical Manual

1MAC504801-IB E
4.1.6.4
4.1.6.5
4.1.6.6
4.1.6.7
4.1.6.8
4.1.6.9
4.1.6.10
4.1.6.11
620 series ANSI
Technical Manual
The function also contains a blocking functionality. It is possible to block function
outputs.

Operation principle

See function 51N.

Measurement modes

See function 51N.

Timer characteristics

See function 51N.

Application

Electric power lines experience faults for many reasons. In most cases, electrical faults
manifest in mechanical damage, which must be repaired before returning the line to
service.
Most of these faults are ground faults. A small percentage of the ground faults have a very
large impedance. They are comparable to load impedance and consequently have very
little fault current. These high impedance faults do not pose imminent danger to power
system equipment. However, they are a considerable threat to people and property. If the
natural unbalance in the system is low, the sensitive earth-fault protection can be used to
detect the ground fault.

Signals

See function 51N.

Settings

See function 51N.

Monitored data

See function 51N.

Technical data

See function 50N.
Section 4
Protection functions
233