ABB REL650 Applications Manual page 148

Section 6
Impedance protection
142
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
gives the minimum recommended reactive reach.
³ ×
X1 1.44 X1
PHS Zm
EQUATION1309 V1 EN
³ ×
X0 1.44 X0
PHS Zm
EQUATION1310 V1 EN
where:
X1 is the reactive reach for the zone to be covered by FDPSPDIS (21), and the constant
Zm
1.44 is a safety margin
X0 is the zero-sequence reactive reach for the zone to be covered by FDPSPDIS (21)
Zm
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 62
³ ×
1.1 RFPG
RFltFwdPG
min
EQUATION1724 V2 EN
where:
RFPG RFPG for the longest overreaching zone to be covered by FDPSPDIS (21).
is the setting
Zm
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.
gives the minimum recommended resistive reach.
zm
1MRK 506 334-UUS A
60 and equation 61
(Equation 60)
(Equation 61)
(Equation 62)
Application manual