ABB 511 Series - Page 5

IB
-
7.2
.
1.7
-
1
PAGE
5
SOLID
-
STATE
OVERCURRENT
RELAYS
OUTPUT
CIRCUIT
The
CIRCUIT
-
SHIELD
overcurrent
relay
energizes
the
breaker
trip
coil
by
means
of
an
output
SCR
.
Two
SCR
’
s
are
provided
,
one
for
the
time
delay
and
pne
for
the
instantaneous
circuit
as
indicated
in
the
wiring
diagram
shown
in
Figure
1
.
As
shown
,
relay
terminal
7
is
connected
to
the
control
power
positive
,
with
the
trip
coil
connected
to
relay
terminal
12
through
a
52
/
a
contact
.
SCR
A
is
gated
by
the
time
delay
circuit
,
while
SCR
B
is
gated
by
the
instantaneous
circuit
.
Note
that
once
an
SCR
is
gated
(
turned
on
)
,
it
will
remain
in
conduction
until
its
anode
current
falls
below
its
holding
current
which
typically
is
5
to
20
milliamperes
.
Consequently
,
the
trip
coil
current
must
be
interrupted
with
the
52
/
a
contact
.
INPUT
CURRENT
RATINGS
Input
Current
,
1
0
or
3
0
(
CT
Secondary
Amperes
)
Tap
Range
.
A
Time
0
1
-
0.5
0.5
-
2.0
1.5
-
6.0
2.5
-
5.0
2.5
-
10
300
multiples
of
pickup
tap
setting
or
235
A
rms
.
whichever
is
less
.
1
Second
390
A
rms
4
-
12
Continuous
All
Ranges
1.5
multiples
of
pickup
tap
setting
.
BURDEN
The
burden
of
the
Circuit
Shield
overcurrent
relay
is
very
low
,
allowing
the
use
of
current
transformers
which
would
give
unsatisfactory
performance
if
they
were
driving
electro
-
mechanical
relays
.
Because
the
input
characteristic
of
the
Circuit
Shield
relay
is
nonlinear
,
an
impedance
cannot
be
specified
,
however
,
the
burden
voltage
across
the
relay
current
inputterminals
can
be
readily
calculated
for
any
given
value
of
current
transformer
secondary
current
:
OUTPUT
TRIP
CIRCUIT
RATINGS
Max
.
Current
,
Amps
DC
Range
of
Operation
Nominal
Voltage
6
Cycles
1
Second
Continuous
24
Vdc
32
Vdc
48
Vdc
125
Vdc
250
Vdc
175
Vdc
350
Vdc
18
-
30
24
-
40
28
-
60
70
-
140
140
-
280
100
-
195
200
-
385
1.0
TAP
Roc
+
Is
x
R
V
=
IT
(
AMPS
)
OHMS
30
1
15
V
=
burden
voltage
(
volts
)
Is
=
current
transformer
secondary
current
(
amperes
)
IT
=
relay
pickup
current
tap
setting
(
amperes
)
R
=
D
C
.
resistance
of
relay
input
circuit
(
ohms
)
(
select
from
table
)
0
5
092
0.6
.
078
0
8
065
*
Capacitor
Trip
Applications
1.0
055
048
1 2
TARGET
CIRCUITS
The
target
indicators
for
the
TIME
and
INST
,
circuits
are
polarity
sensitive
devices
which
are
set
by
current
flow
through
the
corresponding
trip
SCR
.
Target
reset
is
accomplished
by
the
control
power
connection
(
terminals
7
and
8
of
Figure
1
)
through
the
TARGET
RESET
pushbutton
.
Standard
relays
have
2
targets
TIME
and
INST
.
Three
phase
relays
may
be
specially
ordered
with
5
targets
—
TIME
,
INST
,
and
PHASE
targets
.
These
3
additional
targets
wil
indicate
which
phase
currents
are
in
excess
of
tap
setting
when
the
relay
trips
the
breaker
.
.
040
1.5
2.0
032
NOTES
:
1.5
.
042
1
.
for
units
with
0.1
to
0.5
A
tap
range
,
the
Is
x
R
term
is
negligible
.
2.0
034
2
,
5
038
2
.
for
units
with
2
to
5
A
tap
range
,
use
values
shown
for
1.5
to
6
A
unit
.
3.0
.
026
4.0
.
022
5.0
020
6.0
.
0185
4
.
020
5
.
020
6
.
0185
7
.
0175
FREQUENCY
RATING
See
page
17
.
8
.
017
10
.
0165
12
.
0165
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