Distance Protection - ABB RED650 Applications Manual

1MRK 505 393-UEN B
22.1.6.2
Line differential protection RED650 2.2 IEC
Application manual
I
³ = × ×
E E 30 I
al alreq rt
I
EQUATION1412 V2 EN-US
where:
I The rated primary current of the power transformer (A)
rt

Distance protection

The current transformers must have a rated equivalent limiting secondary e.m.f. E
that is larger than the maximum of the required rated equivalent limiting secondary
e.m.f. E below:
alreq
I I
³ = ×
k max sr
E E
al alreq
I
pr
EQUATION1080 V2 EN-US
I I
³ = ×
kzone1 sr
E E
al alreq
I
pr
EQUATION1081 V2 EN-US
where:
I Maximum primary fundamental frequency current for close-in forward and
kmax
reverse faults (A)
I Maximum primary fundamental frequency current for faults at the end of zone 1
kzone1
reach (A)
I The rated primary CT current (A)
pr
I The rated secondary CT current (A)
sr
I The rated current of the protection IED (A)
r
R The secondary resistance of the CT (W)
ct
R The resistance of the secondary wire and additional load (W). In solidly earthed
L
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.
S The burden of an IED current input channel (VA). S
R
A and S
Table continues on next page
æ ö
S
× + +
sr R
R R
ç ÷
ct L
2
I
è ø
pr
r
æ ö
S
× × + +
R
a R R
ç ÷
ct L
2
I
è ø
r
æ ö
S
× × + +
R
k R R
ç ÷
ct L
2
I
è ø
r
=0.150 VA/channel for I
R r
Section 22
Requirements
=0.020 VA/channel for I
R
=5 A
(Equation 135)
M11619-3 v5
al
(Equation 136)
(Equation 137)
=1
r
429