ABB CIRCUIT SHIELD 87T - Page 21

Transformer
Differential
Relay
IB
7.6
.
1.7
-
4
Page
21
oAM
A
°
Figure
12
a
:
Branch
A
Ammeters
Variable
Resistors
Typical
Test
Connections
O
AM
o
Harmonic
Restraint
Test
using
voltage
source
and
built
-
in
test
diode
.
B
40
-
120
Vac
Source
Branch
B
Source
is
60
Hz
for
60
Hz
units
,
50
Hz
for
50
Hz
rated
units
.
Apply
dc
control
voltage
per
relay
nameplate
rating
.
(
+
)
Resistor
required
between
terminals
9
and
10
.
See
page
14
.
DC
Control
Voltage
87
T
&
o
(
-
)
8
7
6
o
°
1
o
o
13
14
13
(
J
16
12
JUL
10
9
Diode
Shorting
—
y
^
~
Swltch
6
O
Contact
Monitor
2.0
1.8
v
n
<
u
m
O
r
—
i
1.6
u
1
B
/
J h
=
~
2 1 2
-
v
5
-
H
-
-
C
o
H
4
J
1.4
•
H
3
W
CP
1.2
c
•
H
4
J
Formu
1
as
:
u
o
1.0
JC
0.2121
A
0.51
A
+
IB
H
0
)
.
8
o
•
H
O
A
or
.
6
•
H
3
0.212
-
0.5
H
JL
§
_
<
A
H
IA
CP
.
2
0
16
18
12
14
20
10
8
H
,
Percent
Second
Harmonic
with
Diode
Shorting
Switch
Open
Percent
2
nd
Harmonic
Content
as
a
Function
of
IB
/
IA
Figure
12
b
:
Note
:
Set
IA
with
the
Diode
Shorting
Switch
closed
.
Do
not
readjust
the
current
IA
after
opening
the
switch
.
Open
switch
to
obtain
the
harmonic
content
indicated
on
the
graph
.
Courtesy of NationalSwitchgear.com