Setting Guidelines; Equipment Protection, Such As For Motors, Generators, Reactors And; Transformers; Equipment Protection, Capacitors - ABB Relion REC670 Applications Manual

1MRK 511 358-UEN A
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. Earth-faults in high impedance earthed systems causes, beside the high voltage in the
neutral, high voltages in the two non-faulted phases, (unsymmetrical voltage increase).
OV2PTOV 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) are set via the local HMI or
PCM600.
All the voltage conditions in the system where OV2PTOV 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 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.
8.2.3.2

Equipment protection, capacitors

High voltage will deteriorate the dielectricum and the insulation. The setting has to be well
above the highest occurring "normal" voltage and well below the highest acceptable voltage
for the capacitor.
8.2.3.3

Power supply quality

The setting has to be well above the highest occurring "normal" voltage and below the highest
acceptable voltage, due to regulation, good practice or other agreements.
Application manual
Section 8
Voltage protection
M13852-4 v9
M13852-10 v2
M13852-13 v1
M13852-16 v1
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