Setting Guidelines; Equipment Protection, Such As For Motors, Generators, Reactors And Transformers - ABB Relion 670 Series Applications Manual

1MRK 511 358-UUS A
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.
8.2.3

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.
There is a very wide application area where general overvoltage functions are used. All voltage
related settings are made as a percentage of a settable base primary voltage, which normally is
set to the nominal voltage level (phase-to-phase) of the power system or the high voltage
equipment under consideration.
The time delay for the OV2PTOV (59) can sometimes be critical and related to the size of the
overvoltage - a power system or a high voltage component can withstand smaller overvoltages for
some time, but in case of large overvoltages the related equipment should be disconnected more
rapidly.
Some applications and related setting guidelines for the voltage level are given below:
The hysteresis is for overvoltage functions very important to prevent that a transient voltage over
set level is not "sealed-in" due to a high hysteresis. Typical values should be ≤ 0.5%.
8.2.3.1 Equipment protection, such as for motors, generators, reactors and
transformers
High voltage will cause overexcitation of the core and deteriorate the winding insulation. The
setting has to be well above the highest occurring "normal" voltage and well below the highest
acceptable voltage for the equipment.
Application manual
Section 8
Voltage protection
M13852-4 v9
M13852-10 v2
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