Power Supply Quality - ABB REC670 Applications Manual

1MRK 511 401-UUS A
9.2.3.3
9.2.3.4
9.2.3.5
Bay control REC670 2.2 ANSI
Application manual

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.
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 (%) VBase kV ( ) / 3
EQUATION1713 V2 EN-US
and operation for phase-to-phase voltage over:
> ×
Vpickup (%) VBase(kV)
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.
Section 9
Voltage protection
M13852-16 v1
M13852-19 v6
M13852-22 v10
(Equation 91)
(Equation 92)
247