Setting Guidelines - ABB REB670 Applications Manual

1MRK 505 370-UUS A
8.2.3
Busbar protection REB670 2.2 ANSI
Application manual
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.

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%.
Section 8
Voltage protection
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