Breaker Failure Protection - ABB RELION 670 Series Applications Manual

1MRK 504 152-UEN B
where:
I
kmax
I
kzone1
I
pr
I
sr
I
r
R
ct
R
L
S
R
a
k
23.1.6.3

Breaker failure protection

The CTs must have a rated equivalent limiting secondary e.m.f. E
to the required rated equivalent limiting secondary e.m.f. E
Application manual
Maximum primary fundamental frequency current for close-in forward and
reverse faults (A)
Maximum primary fundamental frequency current for faults at the end of
zone 1 reach (A)
The rated primary CT current (A)
The rated secondary CT current (A)
The rated current of the protection IED (A)
The secondary resistance of the CT (W)
The resistance of the secondary wire and additional load (W). In solidly
earthed systems the loop resistance containing the phase and neutral
wires should be used for phase-to-earth faults and the resistance of the
phase wire should be used for three-phase faults.
In isolated or high impedance earthed systems the resistance of the single
secondary wire can always be used.
The burden of an IED current input channel (VA). S
I =1 A and S =0.150 VA/channel for I
r R
This factor depends on the design of the protection function and can be a
function of the primary DC time constant of the close-in fault current.
This factor depends on the design of the protection function and can be a
function of the primary DC time constant of the fault current for a fault at
the set reach of zone 1.
The a- and k-factors have the following values for the different types of
distance function:
High speed distance: (ZMFPDIS and ZMFCPDIS)
Quadrilateral characteristic:
a = 1 for primary time constant Tp £ 400 ms
k = 3 for primary time constant Tp £ 200 ms
Mho characteristic:
a = 2 for primary time constant Tp £ 400 ms (For a = 1 the delay in
operation due to saturation is still under 1.5 cycles)
k = 3 for primary time constant Tp £ 200 ms
Quadrilateral distance: (ZMQPDIS, ZMQAPDIS and ZMCPDIS, ZMCAPDIS
and ZMMPDIS, ZMMAPDIS)
a = 1 for primary time constant Tp £ 100 ms
a = 3 for primary time constant Tp > 100 and £ 400 ms
k = 4 for primary time constant Tp £ 50 ms
k = 5 for primary time constant Tp > 50 and £ 150 ms
Mho distance: (ZMHPDIS)
a = 1 for primary time constant Tp £ 100 ms
a = 3 for primary time constant Tp > 100 and £ 400 ms
k = 4 for primary time constant Tp £ 40 ms
k = 5 for primary time constant Tp > 40 and £ 150 ms
=0.020 VA/channel for
R
=5 A
r
that is larger than or equal
al
below:
alreq
Section 23
Requirements
M11621-3 v5
721