ABB RELION RET670 User Manual

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
25.1.6.3 Breaker failure protection
M11621-3 v5
The CT
s must have a rated equivalent limiting secondary e.m.f. E
al
that is lar
ger than
or equal to the required rated equivalent limiting secondary e.m.f. E
alreq
below:
sn
R
al alre q CT L
2
pn n
op
I
S
E E 5 I R R
I I
³ = × × + +
æ ö
×
ç ÷
è ø
EQUATION1677 V1 EN-US (Equation 521)
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
n
The nominal 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
grounded
systems. The resistance of a
single secondary wire should be used for faults in high impedance grounded 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 25 1MRK 504 163-UUS A
Requirements
990 Transformer protection RET670 2.2 ANSI
Application manual

ABB RELION RET670 Specifications

General

Brand	ABB
Model	RELION RET670
Category	Protection Device
Language	English