Equipment Protection, Such As For Motors, Generators, Reactors And Transformers; Equipment Protection, Capacitors; Power Supply Quality; High Impedance Grounded Systems - ABB REB670 Applications Manual
Busbar protection 2.1 ansi, relion 670 series
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Also See for REB670:
- Applications manual (554 pages) ,
- Commissioning manual (196 pages) ,
- Operator's manual (116 pages)
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Section 8
Voltage protection
8.2.3.1
8.2.3.2
8.2.3.3
8.2.3.4
236
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 (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.
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.
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 during faults. A metallic single-phase ground-fault causes the
non-faulted phase voltages to increase a factor of √3.
1MRK 505 337-UUS -
Application manual
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