ABB Relion 670 Series Applications Manual page 225

1MRK 511 401-UUS F
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.
9.2.3 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%.
9.2.3.1 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.
9.2.3.2 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.
9.2.3.3 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.
9.2.3.4 High impedance grounded systems
In high impedance grounded systems, ground-faults cause a voltage increase in the non-faulty
phases. Two step overvoltage protection (OV2PTOV, 59) is used to detect such faults. The setting
must be above the highest occurring "normal" voltage and below the lowest occurring voltage
Bay control REC670
Application manual
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Section 9
Voltage protection
M13852-4 v10
M13852-10 v3
M13852-13 v1
M13852-16 v1
M13852-19 v6
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