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CAU TION:
Before p utting relays into service, re
move all blocking which may have been inserted for
the purpose of securing the parts during ship ment ,
make sure that all moving p arts operate freely, in
sp ect the contacts to see that they are clean and
close properly, and operate the relay to check the
settings and el e ctrical connections.
AP P L ICAT I ON
The Typ e TK Relay is an a-c timing relay for
applications requiring a definite time del ay between
the closing of an a- c circuit and the closing or open
ing of other d-e or a-c circuits. Accurate time- set
tings from two seconds to fifty minutes can be ob
tained, and, for any setting, the reset time is less
*
than one second. One typ e having a 2 second to 1 2 5
minutes range is also available .
The relay i s u s ed where time delay i s required
in motor, generator, or rectifier control circuits. It is
also widely used in indu strial application s .
One typ e of t h e relay i s available for use with a
d-e to a-c inverter where a reliable a-c control volt
age is not avai l able. The inverter is d escribed i n
I . L . 4 1- 8 5 6.
CONSTRUCTION AND OP E RATION
The typ e TK rel ay con sists o f a synchronou s
motor, a g e ar train t o provide three di fferent ratios,
a clutch i nterpo sed i n the gear train to p ermit quick
resetting when the relay i s de- energized, a contactor
which carries the main contacts and operates the
clutch,
and a tripping mechanism adj ustabl e for
time-delay.
Synchronous Motor
The motor for driving the gear train is located o n
t h e back plate of t h e gear train assembly in the
lower right-hand corner. It runs at a synchronous
sp eed of 600, 500 or 250 R . P . M. for 60 , 50 or 25
cycle relays respectively. Its b e ari ng has an oil
reservoir with sufficient capacity for sev eral years
SUPE R S E D E S I . L . 4 1 -574 . 1 E
* Denotes change from superseded i s s ue .
INSTALLATION
I N S T R U C T I O N S
TYPE TK TI MING RELAY
Westi nghouse
•
OPERATION
of normal op eration. On relays rated at 230 or high
er, the contactor coil has a t ap brought out at the
proper plac e to act as an auto-transformer to supply
1 15 volts for the motor.
Gear Tra i n and Cl utch
The gear train i s assembl ed as a sep arate unit
and consists of two brass b e aring plates fastened
together at the corners by brass posts. The gear
shafts run at l ow sp e ed s and require no l ubrication.
The three different speeds are obtained by changing
the location of a sliding gear as sembly. This as
sembly consi sts of two gears on a hub that is free
to slide o n the clutch shaft and c an be locked in
any de sired p o sition with a set screw. The hub is
moved to the p osition where the larger gear is op
po site the arrow on the index p l ate corresponding to
the desired time scal e .
T h e clutch i s t w o al uminum discs with serrated
faces, arranged so that they are positively engaged
and disengaged by a spring arm o n the contactor
armature when the l atter is in its closed and open
positions resp ectively. The rear disc is fastened to
a shaft o n the gear train. The front disc i s a run
ning fit on the end of the s ame shaft. The latt·er
disc has fastened to it the pinion which drives the
tripping mechanism. When the relay is energized ,
the clutch discs engage and p ower is transmitted
from the mo tor, through the gear train, to the trip
ping mechanism. W hen the rel ay is de- energized,
the clutch discs are sep arated by the opening of the
contactor armature.
Contactor
The contactor is a clapper typ e element with a
E shaped magnetic frame with a solenoid coil on the
center leg. The moving armature is hinged at the
bottom of the magnetic frame , and held open by a sp ring
b elow the hinge. A spring arm is fastened to the top
center of the armature , and its outer end presses
against the front half o f the clutch when the con
tacto r coil is energized. The position of this arm i s
controlled b y a n adj usting screw on a bracket fast
ened to the front of the armature.
I . L. 4 1 -574. 1 F
•
MAINTENANCE
E F F EC T I V E MARCH 1 975
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