ABB RET670 - Page 356

PHS Zm
X0 1.44 X0³ ×
EQUATION1310 V1 EN (Equation 284)
where:
X1
Zm
is the reactive reach for the zone to be covered by FRPSPDIS (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 FRPSPDIS (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
285 and 286 gives the minimum recommended resistive reach.
A) 60 degrees
1.1 ZmRFFwPG RFPG³ ×
ANSIEQUATION2223 V1 EN (Equation 285)
B) 90 degrees
( )
1
2 1 0
3
Zm Zm ZmRFFwPG R PG R PG RFPG> × × + +
ANSIEQUATION2224 V1 EN (Equation 286)
The security margin has to be increased in the case where φloop<60° to avoid that
FRPSPDIS (21) characteristic cuts off some part of the zone measurement characteristic.
RFFwPP and RFFRvPP must be set in a way that the loop characteristic angle can be
60 degrees (or alternatively the same or lower compared to the measuring zone that
must be covered). If the characteristic angle for IEDs in the 500 series of 90 degrees is
desired, RFFwPP and RFFRvPP must be set to minimum setting values.
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.
Section 3 1MRK504116-UUS C
IED application
350
Application manual