ABB Relion REQ650, Applications Manual

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IEC07000189 V1 EN
Figure 75: Earth fault in Direct earthed system
7.3.3.4 Settings for Two step residual overvoltage protection
GlobalBaseSel : Selects the global base value group used by the function to define
( IBase ), ( UBase ) and ( SBase ).
Operation : Off or On
UBase is used as voltage reference for the voltage. The voltage can be fed to the IED
in different ways:
1. The IED is fed from a normal voltage transformer group where the residual
voltage is created from the phase-to-earth voltages within the protection
software.
2. The IED is fed from a broken delta connection normal voltage transformer group.
In an open delta connection the protection is fed by the voltage 3U0 (single input).
The Setting chapter in the application manual explains how the analog input
needs to be set.
3. 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=U0 (single input). The Setting chapter in the application
manual explains how the analog input needs to be set. ROV2PTOV will measure
the residual voltage corresponding nominal phase-to-earth voltage for a high
impedance earthed system. The measurement will be based on the neutral voltage
displacement.
Section 7
1MRK 505 291-UEN A
Voltage protection
164
Application manual