groups or the RCA_CTL input. Alternatively, the operating sector of the directional
earth-fault protection function can be extended to cover the operating sectors of
both neutral earthing principles. Such characteristic is valid for both unearthed and
compensated network and does not require any modification in case the neutral
earthing changes temporarily from the unearthed to compensated network or vice
versa.
The extended phase angle characteristic is created by entering a value of over 90
degrees for the
Min forward angle
setting; a typical value is 170 degrees (
Min
reverse angle
in case
Directional mode
is set to "Reverse"). The
Max forward angle
setting should be set to cover the possible measurement inaccuracies of current
and voltage transformers; a typical value is 80 degrees (
Max reverse angle
in case
Directional mode
is set to "Reverse").
Figure 195: Extended operation area in directional earth-fault protection
4.2.2.6 Measurement modes
The function operates on three alternative measurement modes: "RMS", "DFT" and
"Peak-to-Peak". The measurement mode is selected with the
Measurement mode
setting.
Table 405: Measurement modes supported by DEFxPDEF stages
Measurement mode DEFLPDEF DEFHPDEF
RMS x x
DFT x x
Peak-to-Peak x x
1MRS757644 H Protection functions
620 series
Technical Manual
399
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