where:
RFPP
Zm
is the setting of the longest reach of the overreaching zones that must be covered by
FRPSPDIS (21).
Equation
246 and 247 are is also valid for three-phase fault. The proposed margin of
25% will cater for the risk of cut of
f of the zone measuring characteristic that might
occur at three-phase fault when FRPSPDIS (21)characteristic angle is changed from 60
degrees to 90 degrees or from 70 degrees to 100 degrees (rotated 30° anti-clock wise).
Section 8 1MRK 504 163-UUS A
Impedance protection
356 Transformer protection RET670 2.2 ANSI
Application manual
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