Setting Guidelines - ABB RELION RET670 Applications Manual

Section 10
Voltage protection
10.2.3
10.2.3.1
10.2.3.2
618
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.
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%.
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.
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.
1MRK 504 163-UUS A
Transformer protection RET670 2.2 ANSI
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