ABB Relion 670 series - Two step residual overvoltage protection ROV2 PTOV (59 N); Introduction; Principle of operation

8.3 Two step residual overvoltage protection ROV2PTOV
(59N)
Function description IEC 61850
identification
IEC 60617
identification
ANSI/IEEE C37.2
device number
Two step residual overvoltage
protection
ROV2PTOV
3U0
TRV V1 EN
59N
8.3.1 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.
8.3.2 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
0
. The residual voltage can
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.
Section 8 1MRK505222-UUS C
Voltage protection
518
Technical reference manual