Operation Principle - ABB RELION REX640 Technical Manual

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Protection functions

in this document. The configuration can be written to the protection relay once the

mismatch is corrected.

Operation principle

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

corresponding parameter values are "On" and "Off".

The operation of PHPTOV can be described using a module diagram. All the modules

in the diagram are explained in the next sections.

GUID-11C63ED6-BA36-431F-8D8C-C80E9771B332 V1 EN

Functional module diagram

Level detector

The fundamental frequency component of the measured three-phase voltages are

compared phase-wise to the set value of the Start value setting. If the measured value

is higher than the set value of the Start value setting, the level detector enables the

phase selection logic module. The Relative hysteresis setting can be used for

preventing unnecessary oscillations if the input signal slightly differs from the Start

value setting. After leaving the hysteresis area, the start condition has to be fulfilled

again and it is not sufficient for the signal to only return to the hysteresis area.

The Voltage selection setting is used for selecting phase-to-earth or phase-to-phase

voltages for protection.

For the voltage IDMT operation mode, the used IDMT curve equations contain

discontinuity characteristics. The Curve Sat relative setting is used for preventing

undesired operation.

For a more detailed description of the IDMT curves and the use of the

Curve Sat Relative setting, see the

overvoltage protection

IDMT curve saturation of

section in this manual.

1MRS759142 C

Technical Manual

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