ABB RED650, Applications Manual

Page: 103 / 454

op
p
Measured
a
t k b
I
c
IMaxAddDelay
= × +
-
æ ö
ç ÷
ç ÷
ç ÷
æ ö
ç ÷
ç ÷
ç ÷
è ø
è ø
EQUATION1418 V1 EN-US
(Equation 13)
where:
t
op
is operate time
k is time multiplier of the inverse time curve
a, b, c, p are settings that will model the inverse time characteristic
6.1.3.6 Settings examples
M12541-349 v3
M12941-3 v8
Setting example with a power transformer in the protected zone
Figure 44 shows a line with a power transformer in the protected zone. Circuit
impedances are presented in Figure 45 . The protected zone is limited by three
current transformers: CT1, CT2 and CT3. IEDs are situated in two separate
substations 1 and 2.
The circuit is protected by two terminals 1 and 2. These terminals process the same
data except for minor distortion in data that takes place during communication
between them. Both terminals operate as masters. If at least one of them indicates
an internal fault, the protected circuit is disconnected.
IED 2
Line 50 km
CT 3
Substation 2
Substation 1
Current samples from terminals 2 and 3
Current samples from terminal 1
CT 2
Yd1
200 MVA,
220 / 70 kV,
525 / 1650 A
Y d
220 kV, 600 A
CB 1
te
rm
in
a
l 2
t
e
rm
in
a
l 3
CB 2
CB 3
te
rm
in
a
l 1
CT 1
IED 1
IEC05000534-2-en.vsdx
IEC05000534 V2 EN-US
Figure 44: Line differential protection with a power transformer in the
protected zone
1MRK 505 393-UEN B
Section 6
Differential protection
Line differential protection RED650 2.2 IEC 97
Application manual