ABB Relion 650 Series Applications Manual page 250

Section 16
Requirements
R
CT
R
L
S
R
Independent of the value of I
³
E E
a l a lre q ma x
EQUATION1680 V1 EN-US
where
I
kmax
16.1.6.5 Directional phase and residual overcurrent protection
If the directional overcurrent function is used the CTs must have a rated equivalent secondary
e.m.f. E
al
³
E E
a l a lre q
EQUATION1681 V1 EN-US
where:
I
kmax
I
pn
I
sn
I
n
R
CT
R
L
S
R
244
The secondary resistance of the CT (W)
The resistance of the secondary cable and additional load (W). The loop
resistance containing the phase and neutral wires, must be used for faults
in solidly grounded systems. The resistance of a single secondary wire
should be used for faults in high impedance grounded systems.
The burden of an IED current input channel (VA). S
I =1 A and S =0.250 VA/channel for I
r R
the maximum required E
op
æ
I
×
= ×
I s n R
ç
k ma x
CT
I
è
pn
Maximum primary fundamental frequency current for close-in faults (A)
that is larger than or equal to the required equivalent secondary e.m.f. E
æ
I
×
= × +
I s n R R
ç
k ma x
CT
I
è
pn
Maximum primary fundamental frequency current for close-in forward and reverse faults (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 cable and additional load (W). The loop resistance containing the phase
and neutral wires, must be used for faults in solidly grounded systems. The resistance of a single
secondary wire should be used for faults in high impedance grounded systems.
The burden of an IED current input channel (VA). S
for I =5 A
r
© Copyright 2013 ABB. All rights reserved
=5 A
r
al
ö
S
+ +
R R
÷
L
2
I
ø
n
ö
S
+
R
÷
L
2
I
ø
n
=0.010 VA/channel for I
r
=0.010 VA/channel for
R
is specified according to the following:
alreq
=1 A and S =0.250 VA/channel
r r
Busbar protection REB650
1MRK 505 287-UUS B
(Equation 35)
M11624-3 v5
below:
(Equation 36)
Application manual