ABB RER670 - High Impedance Earthed Systems; Settings for Two Step Residual Overvoltage Protection; Solidly Earthed Systems

9.3.3.1 High impedance earthed systems
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In high impedance earthed systems, an earth fault on one phase will cause a voltage
collapse in that phase. However, the other healthy phase voltage will raise to full
phase-to-phase voltage value. The residual voltage sum 2U
0
will raise to the same
phase-to-phase value during earth fault.
9.3.3.2
Solidly earthed systems
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In solidly earthed systems, an earth fault on one phase is indicated by voltage
collapse in that phase. The other healthy phase will still have normal phase-to-earth
voltage. The residual sum 2U
0
will have the same value as the remaining phase-to-
earth voltage.
9.3.3.3 Settings for two step residual overvoltage protection
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Parameters for ROV2PTOV application function are set via the local HMI or
Protection and Control Manager PCM600.
Common base IED values for primary current (IBase), primary voltage (UBase)
and primary power (SBase) are set in the global base values for settings function
GBASVAL.
GlobalBaseSel: This is used to select GBASVAL function for reference of base
values.
Operation: This is used for residual overvoltage protection Off/On.
UBase (given in GlobalBaseSel) is used as voltage reference for the set pickup
values. UBase shall be set equal to rated phase-to-phase voltage. Note that the set
value for UBase will be multiplied by factor 0.5 within the ROV2PTOV function.
The voltage can be fed to the IED in different ways:
1. The IED is fed from two VTs connected phase-to-ground, where the residual
voltage 2U
0
is calculated internally within the protection.
2. The IED is fed from a single voltage transformer connected to the neutral point
of a power transformer in the power system. In this connection the protection
is fed by the voltage UN=U
0
(single input). Section Analog inputs in the
Application manual explains how the analog input needs to be set.
The setting parameters described below are identical for the two steps (n = step 1
and 2). Therefore the setting parameters are described only once.
OperationStepn: This is to enable/disable operation of step n.
Un>: Set operate overvoltage operation value for step n, given as % of residual
voltage corresponding to UBase:
(%) ( ) / 2Un UBase kV
IECEQUATION050 V2 EN-US (Equation 66)
Section 9 1MRK 506 375-UEN A
Voltage protection
202 Railway application RER670 2.2 IEC
Application manual