Hitachi Relion 670 Series Applications Manual page 420

Section 22
Requirements
22.1.6.3 Breaker failure protection
The CTs must have a rated equivalent limiting secondary e.m.f. E
required rated equivalent limiting secondary e.m.f. E
³
E E
al
EQUATION1380 V2 EN-US
where:
I The primary operate value (A)
op
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 cable and additional load (W). The loop resistance containing the phase and
L
neutral wires, must be used for faults in solidly earthed systems. The resistance of a single secondary wire
should be used for faults in high impedance earthed systems.
S The burden of an IED current input channel (VA). S
R
for I
22.1.6.4 Non-directional instantaneous and definitive time, phase and residual
overcurrent protection
The CTs must have a rated equivalent limiting secondary e.m.f. E
required rated equivalent limiting secondary e.m.f. E
³
E E
al
EQUATION1381 V2 EN-US
where:
I The primary operate value (A)
op
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 cable and additional load (W). The loop resistance containing the phase and
L
neutral wires, must be used for faults in solidly earthed systems. The resistance of a single secondary wire
should be used for faults in high impedance earthed systems.
S The burden of an IED current input channel (VA). S
R
for I
22.1.6.5 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.
414
æ
I
= × × ×
sr
5 I R
ç
alreq op ct
I
è
pr
=5 A
r
æ
I
= × × ×
sr
1,5 I R
ç
alreq op ct
I
è
pr
=5 A
r
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below:
alreq
ö
S
+ +
R
R
÷
L
2
I
ø
r
=0.020 VA/channel for I
R
below:
alreq
ö
S
+ +
R
R
÷
L
2
I
ø
r
=0.020 VA/channel for I
R
82 and Equation 83
1MRK506375-UEN Rev. N
that is larger than or equal to the
al
=1 A and S =0.150 VA/channel
r R
that is larger than or equal to the
al
=1 A and S =0.150 VA/channel
r R
does not need to be fulfilled if the high
Railway application RER670
M11621-3 v5
(Equation 80)
M11622-3 v5
(Equation 81)
M11339-3 v5
Application manual