ABB RET670 - Page 261

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 171 and
equation 172 gives the minimum recommended reactive reach.
PHS Zm
X1 1.44 X1³ ×
EQUATION1309 V1 EN (Equation 171)
PHS Zm
X0 1.44 X0³ ×
EQUATION1310 V1 EN (Equation 172)
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
173 gives the minimum recommended resistive reach.
min
1.1
zm
RFltFwdPG RFPG³ ×
EQUATION1724 V2 EN (Equation 173)
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.
Resistive reach
1MRK504116-UUS C Section 3
IED application
255
Application manual