Toshiba GR-200-5 Instruction Manual page 206

Earth fault overvoltage protection (OVG)
Earth fault overvoltage protection (OVG) function has four stages (OVG1, OVG2, OVG3, and
OVG4); and the time characteristic of each stage can be taken from either definite time or
inverse definite minimum time. The purpose of each stage of the OVG is to detect earth fault
on unearthed, resistance-earthed system or AC generators.
The low voltage settings, which may be applied for OVG elements, are susceptible to any
third harmonic component that may be superimposed on input signals. Therefore, the function
incorporates filters to suppress the third harmonic component.
To simplify the description, only OVG1 is discussed but is applicable to OVG2 and the
others; hence, read the expression for OVG1 as other stages unless a special explanation or
instruction has been provided.
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6F2T0207 (0.01)
GRE200 (5,6)