ABB Relion REQ650, Руководство по применению

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sn R
al alreq op CT L
2
pn r
I S
E E 1,5 I R R
I I
æ ö
³ = × × × + +
ç ÷
è ø
EQUATION1381 V1 EN
(Equation 81)
where:
I
op
The primary operate value (A)
I
pn
The rated primary CT current (A)
I
sn
The rated secondary CT current (A)
I
r
The rated current of the protection IED (A)
R
CT
The secondary resistance of the CT (
W
)
R
L
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 earthed systems. The resistance
of a single secondary wire should be used for faults in high impedance earthed systems.
S
R
The burden of an IED current input channel (VA). S
R
=0.010 VA/channel for I
r
=1 A and S
R
=0.250
VA/channel for I
r
=5 A
16.1.6.3 Non-directional inverse time delayed phase and residual overcurrent
protection
The requirement according to Equation 82 and Equation 83 does not need to be
fulfilled if the high set instantaneous or definitive time stage is used. In this case
Equation
81 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
al
that is larger than or equal
to the required secondary e.m.f. E
alreq
below:
sn R
al alreq op CT L
2
pn r
I S
E E 20 I R R
I
I
æ ö
³ = × × × + +
ç ÷
è ø
EQUATION1076 V1 EN
(Equation 82)
where
I
op
The primary current set value of the inverse time function (A)
I
pn
The rated primary CT current (A)
I
sn
The rated secondary CT current (A)
I
r
The rated current of the protection IED (A)
R
CT
The secondary resistance of the CT (
W
)
R
L
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 earthed
systems. The resistance of a single secondary wire should be used for faults in high
impedance earthed systems.
S
R
The burden of an IED current input channel (VA). S
R
=0.010 VA/channel for I
r
=1 A
and S
R
=0.250 VA/channel for I
r
=5 A
1MRK 505 291-UEN A
Section 16
Requirements
319
Application manual