Reactive reach
The reactive reach in forward direction must as minimum be set to cover the measuring
zone used in the Teleprotection schemes, mostly zone 2. Equation 97 and equation 98
gives the minimum recommended reactive reach.
EQUATION1309 V1 EN (Equation 282)
EQUATION1310 V1 EN (Equation 283)
where:
X1
Zm
is the reactive reach for the zone to be covered by FDPSPDIS (21), and the constant
1.44 is a safety margin
X0
Zm
is the zero-sequence reactive reach for the zone to be covered by FDPSPDIS (21)
The reactive reach in reverse direction is automatically set to the same reach as for forward
direction. No additional setting is required.
Fault resistance reach
The resistive reach must cover RFPG for the overreaching zone to be covered, mostly
zone 2. Consider the longest overreaching zone if correct fault selection is important in the
application. Equation
99 gives the minimum recommended resistive reach.
min
1.1
zm
RFltFwdPG RFPG³ ×
EQUATION1724 V2 EN (Equation 284)
where:
RFPG
Zm
is the setting
RFPG
for the longest overreaching zone to be covered by FDPSPDIS (21).
The security margin has to be increased to at least 1.2 in the case where φloop<60° to avoid
that FDPSPDIS (21) characteristic shall cut off some part of the zone measurement
characteristic.
Phase-to-ground fault in reverse direction
Reactive reach
The reactive reach in reverse direction is the same as for forward so no additional setting
is required.
1MRK 506 369-UUS - Section 8
Impedance protection
Line distance protection REL670 2.2 ANSI 351
Application manual
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