ABB CIRCUIT SHIELD 87T - Page 13

Transformer
Differential
Relay
IB
7.6
.
1.7
-
4
Page
13
.
6
CL
<
.
5
H
-
X
z
.
4
LU
tr
CL
3
O
.
3
Hi
<
GC
LU
a
.
.
2
O
.
1
0
0
SMALLER RESTRAINT
CURRENT
IN
MULTIPLES
OF
TAP
SETTING
Figure
5
:
Typical Operating
Time
0
.
<
X
H
z
LU
DC
GC
3
O
<
cr
LU
CL
O
SMALLER
RESTRAINT
CURRENT
IN
MULTIPLES
OF
TAP
SETTING
o
.
<
X
z
Ui
cr
cr
3
O
LU
2
Ui
0
.
O
SMALLER
RESTRAINT
CURRENT
IN
MULTIPLES
OF
TAP
SETTING
Figure
6
:
Percentage
Differential
Operating
Characteristic
Figure
7
:
Percentage
Differential
Characteristics
at
Low
Currents
for
15
%
,
25
%
,
and
40
%
Settings
showing
minimum
operate
current
as a
function
of
R
.
(
see
Figure
7
for
detail
at
low
restraint
currents
)
Minimum Restraint
Dial
(
R
)
adjustable
from
1.0
to
2.3
.
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