Application - ABB RELION 620 Series Technical Manual

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1MAC504801-IB E

620 series ANSI

Technical Manual

Application

51P/50P is used in several applications in the power system. The applications include but

are not limited to:

Selective overcurrent and short-circuit protection of feeders in distribution and

subtransmission systems

Backup overcurrent and short-circuit protection of power transformers and

Overcurrent and short-circuit protection of various devices connected to the power

system, for example shunt capacitor banks, shunt reactors and motors

General backup protection

51P/50P is used for single-phase, two-phase and three-phase non-directional overcurrent

and short-circuit protection. Typically, overcurrent protection is used for clearing two and

three-phase short circuits. Therefore, the user can choose how many phases, at minimum,

must have currents above the pickup level for the function to trip. When the number of

pickup-phase settings is set to "1 out of 3", the operation of 51P/50P is enabled with the

presence of high current in one-phase.

When the setting is "2 out of 3" or "3 out of 3", single-phase faults are not

detected. The setting "3 out of 3" requires the fault to be present in all three

High PHHPTOC

Instantaneous PHIPTOC

PHLPTOC is used for overcurrent protection. The function contains several types of time-

delay characteristics. PHHPTOC and PHIPTOC are used for fast clearance of very high

overcurrent situations.

Many applications require several steps using different current pickup levels and time

delays. 51P/50P consists of three protection stages:

High 50P-1/2

Instantaneous 50P-3

51P is used for overcurrent protection. The function contains several types of time-delay

characteristics. 50P-1/2 and 50P-3 are used for fast clearance of very high overcurrent

Protection functions

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