Toshiba GRL100-701B Instruction Manual page 149

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Residual overcurrent detector EF and EFL
This detector measures a residual current and its sensitivity can be set. The EF is used for backup
protection. The EFL is used for the earth fault detection of distance protection and VT failure
supervision.
Overvoltage detector OVS1/OVS2/OVG1/OVG2 and undervoltage detector UVS1/UVS2/UVG1/UVG2
The OVS∗ and UVS∗ measure a phase-to-phase voltage while the OVG∗ and UVG∗ measure a
phase-to-earth voltage. These detectors are used for overvoltage and undervoltage protection as
described in Section 2.9.
Residual overvoltage detector OVG
This detector measures a residual voltage and its sensitivity is fixed at 20V. This detector is used
for supervision of VT failure.
Undervoltage detector UVLS and UVLG
The UVLS measures a phase-to-phase voltage while the UVLG measures a phase-to-earth
voltage. Their sensitivity can be set.
These detectors are used for weak infeed tripping.
The following two level detectors require high-speed operation or high-speed reset.
Undervoltage detector UVFS and UVFG
The UVFS measures a phase-to-phase voltage while the UVFG measures a phase-to-earth voltage.
Their sensitivity can be set.
These detectors are commonly used for the VT failure supervision and signal channel test.
Undervoltage detector UVPWI
The UVPWI measures a phase-to-earth voltage and its sensitivity is 30V fixed. The UVPWI is
used for countermeasures for overreaching of a leading-phase distance element at positive phase
weak infeed condition.
Overcurrent detector OCBF
This detector measures A, B, and C phase currents and its sensitivity can be set. This detector is
used for breaker failure protection and resets when the current falls below 80% of the operating
value.
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