ABB Circuit Shield 87B User Manual

High
-
Impedance
Differential
Relays
IB
7.6
.
1.7
-
7
Page
7
Output
Circuit
Contact
Rating
at
:
250
vdc
125
vdc
Tripping
Continuous
Break
30
Amperes
5
Amperes
0.3
Amperes
30
Amperes
5
Amperes
0.1
Amperes
More
than
3000
V
,
IMhz
.
bursts
at
60
Hz
repetition
rate
continuous
.
Transient
Immunity
;
Operating
Temperature
Range
:
Minus
-
30
to
+
70
degrees
C
.
UL
File
No
.
E
103204
UL
Recognized
:
PRINCIPLE OF
OPERATION
The
Type
87
B
differential
relay
contains
solid
-
state
circuits and
offers
high
-
speed
and
sensitive
protection
against
faults
within the
protected
zone
of
substations
or
equipment
.
Its
input
presents
a
high
impedance
burden
to current
transformers
(
see
table
1
)
for
secondary
differential
currents
below
0.5
amperes
and
corresponding
burden
voltages
below
1000
volts
peak
.
Leakage
current
through
the
relay
varistors
at
these
levels
is
negligible
.
The
voltage
pickup
setting
is
made
by
means
of
a
switch and trimmer
potentiometer
in
a
voltage
divider circuit
.
The
relay
responds
to
modified
instantaneous
voltage
increase
across
its
terminals above the
set
point
during
internal faults
.
The
pickup
voltage
should be
set
above the moderate
voltages
which
may
occur
under
external
or
through
-
fault conditions due
to
unequal
performance
or
saturation
of
CT
'
s
.
Filter and
delay
circuits
are
provided
against
system
transients
,
RFI
,
and
flux
exchange
between
current
transformers
.
The
relay
is
equipped
with
voltage
-
limiting
power
resistors
(
metal oxide
varistors
)
to
limit
the
input
voltage
to
safe
values
during
internal
system
faults
.
Input
burden
at
heavy
faults is
in
essence
,
a
relatively
high
dc
voltage
in
series with
a
resistance
of
a
few
ohms which
practically
does
not
impede
the build
up
of
CT
summation
currents
.
Hence
,
the
relay
absorbs
instantaneous
power
in
the order
of
kilowatts
while
responding
to
high
currents
and has
assigned
wattsecond
limits
.
The
energy
delivered
by
current
transformers
depends
on
their saturation
voltage
(
or
VA
rating
)
,
ratio
,
and fault
current
magnitude
.
The
Type
87
B
relay
is
primarily
designed
to
operate
a
fast
lockout
relay
which
,
in
turn
,
short circuits the
relay
inputs
and
trips
associated circuit
breakers
.
The
input
side
of
the
relay
is
isolated
from
the
output
circuits
by
an
optocoupler
.
The
output
side
consists
of
a
dry
contact
and
associated
clamping
,
delay
,
polarity
and
power
supply
circuits
.
A
target
is
provided
to
give
a
permanent
indication
of
relay
system
operation
and is
reset
by
means
of
the
front
panel
push
-
button
.
The built
-
in
test
feature
allows
operational
trip
test
of
the
Type
87
B
and
lockout
relay
.
When
a
differential
trip
occurs
,
the
output
contact
is
driven
closed
for
a
minimum
of
200
milliseconds
(
400
typical
)
then
automatically
resets
.
If
trip
level
input
is
maintained
,
the
relay
will continue
to
cycle
through
the
trip
and
reset
functions
.
Courtesy of NationalSwitchgear.com

ABB Circuit Shield 87B Specifications

General

Brand	ABB
Model	Circuit Shield 87B
Category	Relays
Language	English