ABB Relion 650 Series Applications Manual page 105

1MRK 505 287-UUS B
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:
Equipment protection, such as for motors, generators, reactors and
transformers
High voltage can cause overexcitation of the core and deteriorate the winding insulation. The
setting must be above the highest occurring "normal" voltage and below the highest acceptable
voltage for the equipment.
Equipment protection, capacitors
High voltage can deteriorate the dielectricum and the insulation. The setting must be above the
highest occurring "normal" voltage and below the highest acceptable voltage for the capacitor.
High impedance grounded systems
In high impedance grounded systems, ground-faults cause a voltage increase in the non-faulty
phases. OV2PTOV (59) can be 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.
The following settings can be done for Two step overvoltage protection
GlobalBaseSel : Selects the global base value group used by the function to define ( IBase ), ( VBase )
SBase ).
and (
ConnType: Sets whether the measurement shall be phase-to-ground fundamental value, phase-to-
phase fundamental value, phase-to-ground RMS value or phase-to-phase RMS value.
Operation: Disabled/Enabled .
OV2PTOV (59) measures the phase-to-ground voltages, or phase-to-phase voltages as selected.
The function will operate if the voltage gets higher than the set percentage of the global set base
voltage
>
V (%)
EQUATION1713 V2 EN-US
and operation for phase-to-phase voltage over:
Vpickup
EQUATION1992-ANSI V1 EN-US
Busbar protection REB650
Application manual
VBase . This means operation for phase-to-ground voltage over:
×
VBase kV ( ) / 3
> ×
(%) VBase(kV)
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Section 8
Voltage protection
(Equation 20)
(Equation 21)
99