Westinghouse
I
.
L
.
41-759.3
INSTALLATION
•
OPERATION
•
MAINTENANCE
INSTRUCTIONS
TYPE AR HIGH SPEED AUXILIARY RELAY
HIGH THRESHOLD DESIGN
CAUTION:
Before putting protection relays into
service, remove all blocking which may have been
inserted for the purpose of securing the parts during
shipment. Make sure that all moving parts operate
freely. Inspect the contacts to see that they are
clean and can close properly. Operate the relay to
check the settings and electrical connections.
APPLICATION
The high threshold AR relay is a sensitive high
speed auxiliary relay with 4 N
.0.
contacts designed
to be secure against misoperation due to inadvertent
grounding of a station battery or the trip lead. With
the battery balanced with respect to ground, the
maximum momentary voltage that can be applied to
an auxiliary relay for either of these grounds is half
battery voltage . The operating level of the high
threshold AR exceeds these levels.
CONSTRU CTION AND
OP ERATION
AR Unit
The relay consists of four stationary contact
screws, four leaf spring moving contacts, a moving
armature and card assembly, which operates the
moving contacts; a U shaped laminated core, a coil,
a frame, a molded insulation block and a series
resistor. Refer to Fig. 1 and
2.
A zener diode is
connected around the coil to eliminate the genera
tion of induced voltages upon interruption of the
coil circuit.
The armature and card assembly slip over a hinge
pin which is inserted in the laminations . The moving
and stationary contacts are mounted on the molded
insulation block. The molded block and coil and
lamination assembly are mounted to the frame. All
contacts are fine silver .
When the coil and resistor are energized, the
armature is attracted to the laminations. The card
moves with the armature thereby operating the
moving contacts. The tension of the moving contacts
is the resetting force.
S UPERSED ES L914464
Complete Revision
High speed operation is obtained by the low
inertia of the moving parts, a sensitive electromag
net, and the proper L/R ratio of the operating circuit.
Operation Indicator
(0.1.)
(When Supplied)
The de operation indicator is a small clapper
type device. A magnetic armature is attracted to the
magnetic core upon .energization of the switch.
During this operation two fingers on the armature
deflect a spring located on the front of the switch,
which allows the operation indicator target to drop.
The front spring, in addition to holding the target,
provides restraint for the armature and thus controls
the pickup value of the switch.
Indicating Contactor Switch Unit (ICS)
(When Supplied)
The de indicating contactor switch is a small
clapper type device. A magnetic armature, to which
leaf-spring mounted contacts are attached, is attrac
ted to the magnetic core upon energizing of the
switch. When the switch closes, the moving contacts
bridge two stationary contacts, completing the trip
circuit. Also during this operation two fingers on
the armature deflect a spring located on the front of
the switch, allowing the operation indicator target
to drop.
The front spring, in addition to holding the target,
provides restraint for the armature and thus controls
the pickup value of the switch.
C HARA CTERIS TICS
The relay operates in 4 milliseconds for an energy
input of
10
watts .
The relay is adjusted to have a pickup value less
than 80% of rating, but not less than
50%
of the
typical battery equalizing charge voltage. i.e. mini
mum pickup is greater than
TABLE I
28
volts for 48 volt rating
70
volts for
125
volt rating
140 volts for
250
volt rating
EF F ECTIV E MARCH 1976
www
. ElectricalPartManuals
. com
