10.2.3 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 are wide applications where general overvoltage functions are used. All voltage
related settings are made as a percentage of a settable base primary voltage, which is
normally 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%.
10.2.3.1 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.
10.2.3.2 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.
10.2.3.3 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.
Section 10 1MRK 506 369-UUS -
Voltage protection
572 Line distance protection REL670 2.2 ANSI
Application manual
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