Hitachi Relion 670 Series Applications Manual page 419

1MRK506375-UEN Rev. N
³
E E
al
EQUATION1414 V2 EN-US
where:
I Maximum primary fundamental frequency current that passes two main CTs without passing the power
f
transformer (A)
22.1.6.2 Distance protection
The current transformers must have a rated equivalent limiting secondary e.m.f. E
the maximum of the required rated equivalent limiting secondary e.m.f. E
³
E E
al
EQUATION1080 V2 EN-US
³
E E
al
EQUATION1081 V2 EN-US
where:
I
kmax
I
kzone1
I
pr
I
sr
I
r
R
ct
R
L
S
R
a
k
Railway application RER670
Application manual
æ
I
= × × +
sr
I R R
ç
alreq f ct
I
è
pr
æ
I I
= × × ×
k max sr
a R
ç
alreq
I
è
pr
æ
I I
= × × ×
kzone1 sr
k R
ç
alreq
I
è
pr
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
and S =0.150 VA/channel for I
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:
Quadrilateral distance: (ZRCPDIS and ZRWPDIS)
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
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ö
S
+
R
÷
L
2
I
ø
r
ö
S
+ +
R
R
÷
ct L
2
I
ø
r
ö
S
+ +
R
R
÷
ct L
2
I
ø
r
=5 A
r
that is larger than
al
below:
alreq
=0.020 VA/channel for I =1 A
R r
Section 22
Requirements
(Equation 77)
M11619-3 v6
(Equation 78)
(Equation 79)
413