ABB Relion 650 Series Applications Manual page 249

1MRK 505 287-UUS B
16.1.6.3 Non-directional instantaneous and definitive time, phase and residual
overcurrent protection
The CTs must have a rated equivalent secondary e.m.f. E
required secondary e.m.f. E
³
E E
a l a lre q
EQUATION1678 V1 EN-US
where:
I
op
I
pn
I
sn
I
n
R
CT
R
L
S
R
16.1.6.4 Non-directional inverse time delayed phase and residual overcurrent
protection
The requirement according to Equation
set instantaneous or definitive time stage is used. In this case Equation is the only necessary
requirement.
If the inverse time delayed function is the only used overcurrent protection function the CTs must
have a rated equivalent secondary e.m.f. E
e.m.f. E
alreq
³
E E
a l a lre q
EQUATION1679 V1 EN-US
where
I
op
I
pn
I
sn
I
n
Table continues on next page
Busbar protection REB650
Application manual
below:
alreq
æ
I
×
= × × +
1.5 I s n R
ç
op
CT
I
è
pn
The primary operate value (A)
The rated primary CT current (A)
The rated secondary CT current (A)
The nominal 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
below:
æ
I
×
= × × +
20 I s n R
ç
op
CT
I è
pn
The primary current set value of the inverse time function (A)
The rated primary CT current (A)
The rated secondary CT current (A)
The nominal current of the protection IED (A)
© Copyright 2013 ABB. All rights reserved
al
ö
S
+
R R
÷
L
2
I
ø
n
=0.010 VA/channel for I
R
34 and Equation 35
that is larger than or equal to the required secondary
al
ö
S
+
R R
÷
L
2
I ø
n
that is larger than or equal to the
=1 A and S =0.250 VA/channel
r R
does not need to be fulfilled if the high
Section 16
Requirements
M11622-3 v4
(Equation 33)
M11339-3 v4
(Equation 34)
243