ABB Relion 670 Series Technical Reference Manual page 524

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Voltage protection

Two step residual overvoltage protection ROV2PTOV

Function description

Two step residual overvoltage

Introduction

Residual voltages may occur in the power system during ground faults.

Two step residual overvoltage protection ROV2PTOV (59N) function calculates the

residual voltage from the three-phase voltage input transformers or measures it from a

single voltage input transformer fed from a broken delta or neutral point voltage

transformer.

ROV2PTOV (59N) has two voltage steps, each with inverse or definite time delay.

Reset delay ensures operation for intermittent ground faults.

Principle of operation

Two step residual overvoltage protection ROV2PTOV (59N) is used to detect high single-

phase voltage, such as high residual voltage, also called 3V

be measured directly from a voltage transformer in the neutral of a power transformer

or from a three-phase voltage transformer, where the secondary windings are

connected in an open delta. Another possibility is to measure the three-phase voltages

and internally in the IED calculate the corresponding residual voltage and connect this

calculated residual voltage to ROV2PTOV (59N). ROV2PTOV (59N) has two steps

with separate time delays. If the single-phase (residual) voltage remains above the set

value for a time period corresponding to the chosen time delay, the corresponding

TRIP signal is issued.

The time delay characteristic is individually chosen for the two steps and can be either,

definite time delay or inverse time delay.

The voltage related settings are made in percent of the base voltage, which is set in kV,

phase-phase.

identification

1MRK505222-UUS C

ANSI/IEEE C37.2

device number

. The residual voltage can

Technical reference manual

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