ABB Relion 670 Series Applications Manual page 229

1MRK 505 370-UUS Rev. K
8.2.3.3 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.
8.2.3.4 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 during faults. A metallic
single-phase ground-fault causes the non-faulted phase voltages to increase a factor of √3.
8.2.3.5 The following settings can be done for the two step overvoltage protection
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.
VBase (given in GlobalBaseSel): Base voltage phase to phase in primary kV. This voltage is used as
reference for voltage setting. OV2PTOV (59) measures selectively phase-to-ground voltages, or phase-
to-phase voltage chosen by the setting ConnType. The function will operate if the voltage gets lower than
the set percentage of VBase. When ConnType is set to PhN DFT or PhN RMS then the IED
automatically divides set value for VBase by √3. When ConnType is set to PhPh DFT or PhPh RMS then
set value for VBase is used. Therefore, always set VBase as rated primary phase-to-phase ground
voltage of the protected object. If phase to neutral (PhN) measurement is selected as setting, the
operation of phase-to-ground over voltage is automatically divided by sqrt3. This means operation for
phase-to-ground voltage over:
>
V (%)
EQUATION1713 V2 EN-US
and operation for phase-to-phase voltage over:
Vpickup
EQUATION1992-ANSI V1 EN-US
The below described setting parameters are identical for the two steps (n = 1 or 2). Therefore the setting
parameters are described only once.
Characteristicn: This parameter gives the type of time delay to be used. The setting can be Definite time,
Inverse Curve A, Inverse Curve B, Inverse Curve C or I/Prog. inv. curve. The choice is highly dependent
of the protection application.
OpModen: This parameter describes how many of the three measured voltages that should be above the
set level to give operation. The setting can be 1 out of 3, 2 out of 3, 3 out of 3. In most applications it is
sufficient that one phase voltage is high to give operation. If the function shall be insensitive for single
phase-to-ground faults 1 out of 3 can be chosen, because the voltage will normally rise in the non-faulted
phases at single phase-to-ground faults. In subtransmission and transmission networks the UV function
is mainly a system supervision function and 3 out of 3 is selected.
Busbar protection REB670
Application manual
×
VBase kV ( ) / 3
> ×
(%) VBase(kV)
© 2017 - 2021 Hitachi Power Grids. All rights reserved
Section 8
Voltage protection
M13852-16 v1
M13852-19 v6
M13852-22 v10
(Equation 74)
(Equation 75)
223