ABB RED650, Руководство по применению, Страница: 436 / 454

a 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.
k 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:
High speed distance: (ZMFPDIS and ZMFCPDIS)
Quadrilateral characteristic:
a = 1 for primary time constant Tp
£
400 ms
k = 3 for primary time constant Tp £ 200 ms
Mho characteristic:
a = 2 for primary time constant Tp £ 400 ms (For a = 1 the delay in operation
due to saturation is still under 1.5 cycles)
k = 3 for primary time constant Tp £ 200 ms
Quadrilateral distance: (ZMQPDIS, ZMQAPDIS and ZMCPDIS, ZMCAPDIS and
ZMMPDIS, ZMMAPDIS)
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
Mho distance: (ZMHPDIS)
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 £ 40 ms
k = 5 for primary time constant Tp
>
40 and
£
150 ms
22.1.6.3 Breaker failure protection
M11621-3 v5
The CTs must have a rated equivalent limiting secondary e.m.f. E
al
that is larger
than or equal to the required rated equivalent limiting secondary e.m.f. E
alreq
below:
sr R
al alreq op ct L
2
pr
r
I S
E E 5 I R R
I I
æ ö
³ = × × × + +
ç ÷
è ø
EQUATION1380 V2 EN-US
(Equation 138)
where:
I
op
The primary operate value (A)
I
pr
The rated primary CT current (A)
I
sr
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
=0.020 VA/channel for I
r
=1 A and
S
R
=0.150 VA/channel for I
r
=5 A
Section 22
1MRK 505 393-UEN B
Requirements
430 Line differential protection RED650 2.2 IEC
Application manual