Toshiba GR200 Series Instruction Manual page 274

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Earth fault overvoltage protection (OVG)

The earth fault overvoltage protection (OVG) function has two stages (OVG1 and OVG2); 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 setting, which may be applied for an OVG element, is susceptible to any

third harmonic component that may be superimposed on an input signal. Therefore, the

function incorporates the filter to suppress the third harmonic component.

To simplify the description, only OVG1 is discussed but is applicable to OVG2; hence,

read the expression for OVG1 as OVG2 for the OVG 2nd stage unless a special explanation or

instruction has been provided.

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The implementation of particular features is dependent upon the selection of

hardware and the configuration of functions. Several IED models do not support certain

features. To determine whether a particular feature has been implemented within an IED,

identify the IED ordering number; and check the order number for the "G&T position" whilst

referring to the comparison table below. For more information, see

Table 2.14-1 Comparative table in respective ordering numbers

✓: Applicable

Main features

Ordering No. at "G&T"

6F2S1915 (0.46)

Appendix: Ordering

GRZ200 (Soft 031 & 032)