Two Step Residual Overvoltage Protection Rov2Ptov; Identification; Application; Setting Guidelines - ABB RET650 Applications Manual

1MRK 504 169-UEN A
8.3
8.3.1
8.3.2
8.3.3
Transformer protection RET650 2.2 IEC
Application manual
Two step residual overvoltage protection
ROV2PTOV

Identification

Function description
Two step residual overvoltage
protection

Application

Two step residual overvoltage protection ROV2PTOV is primarily used in high
impedance earthed distribution networks, mainly as a backup for the primary earth-
fault protection of the feeders and the transformer. To increase the security for
different earth-fault related functions, the residual overvoltage signal can be used
as a release signal. The residual voltage can be measured either at the transformer
neutral or from a voltage transformer open delta connection. The residual voltage
can also be calculated internally, based on the measurement of the three phase-to-
earth voltages.
In high impedance earthed systems the residual voltage will increase in case of any
fault connected to earth. Depending on the type of fault and fault resistance the
residual voltage will reach different values. The highest residual voltage, equal to
three times the phase-to-earth voltage, is achieved for a single phase-to-earth fault.
The residual voltage increases approximately to the same level in the whole system
and does not provide any guidance in finding the faulted component. Therefore,
ROV2PTOV is often used as a backup protection or as a release signal for the
feeder earth-fault protection.

Setting guidelines

All the voltage conditions in the system where ROV2PTOV performs its functions
should be considered. The same also applies to the associated equipment, its
voltage withstand capability and time characteristic.
All voltage-related settings are made as a percentage of a settable base voltage,
which shall be set to the primary nominal voltage (phase-phase) level of the power
system or the high-voltage equipment under consideration.
The time delay for ROV2PTOV is seldom critical, since residual voltage is related
to earth faults in a high-impedance earthed system, and enough time must normally
be given for the primary protection to clear the fault. In some more specific
Voltage protection
IEC 61850 IEC 60617

identification

identification
ROV2PTOV
2(U0>)
IEC15000108 V1 EN-US
Section 8
IP14546-1 v4
SEMOD54295-2 v6
ANSI/IEEE C37.2
device number
59N
M13809-3 v8
M13853-3 v8
151