Application - ABB REL650 Applications Manual

1MRK 506 334-UUS A
8.2.2
8.2.3
Application manual

Application

Two step overvoltage protection OV2PTOV (59) is applicable in all situations, where
reliable detection of high voltage is necessary. OV2PTOV (59) is used for supervision and
detection of abnormal conditions, which, in combination with other protection functions,
increase the security of a complete protection system.
High overvoltage conditions are caused by abnormal situations in the power system.
OV2PTOV (59) is applied to power system elements, such as generators, transformers,
motors and power lines in order to detect high voltage conditions. OV2PTOV (59) is used
in combination with low current signals, to identify a transmission line, open in the remote
end. In addition to that, OV2PTOV (59) is also used to initiate voltage correction
measures, like insertion of shunt reactors, to compensate for low load, and thereby
decreasing the voltage. The function has a high measuring accuracy and hysteresis setting
to allow applications to control reactive load.
OV2PTOV (59) is used to disconnect apparatuses, like electric motors, which will be
damaged when subject to service under high voltage conditions. It deals with high voltage
conditions at power system frequency, which can be caused by:
1. Different kinds of faults, where a too high voltage appears in a certain power system,
like metallic connection to a higher voltage level (broken conductor falling down to
a crossing overhead line, transformer flash over fault from the high voltage winding
to the low voltage winding and so on).
2. Malfunctioning of a voltage regulator or wrong settings under manual control
(symmetrical voltage decrease).
3. Low load compared to the reactive power generation (symmetrical voltage decrease).
4. Ground-faults in high impedance grounded systems causes, beside the high voltage
in the neutral, high voltages in the two non-faulted phases, (unsymmetrical voltage
increase).
OV2PTOV (59) prevents sensitive equipment from running under conditions that could
cause their overheating or stress of insulation material, and, thus, shorten their life time
expectancy. In many cases, it is a useful function in circuits for local or remote automation
processes in the power system.
Setting guidelines
The parameters for Two step overvoltage protection (OV2PTOV ,59) are set via the local
HMI or PCM600.
All the voltage conditions in the system where OV2PTOV (59) performs its functions
should be considered. The same also applies to the associated equipment, its voltage and
time characteristic.
Section 8
Voltage protection
259