Westinghouse DK-15, Manual

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Type DK Air Circuit Breaker
General
The
DK
air circuit breaker, complete with all attachments, is a
self-contained unit, and has been mounted, adjusted and calibrated on its
own permanent panel at the factory. It is designed only to be mounted in
a
vertical position,
and all inspections for proper operation must be made
with the breaker main panel held vertically.
Unpacking
Care must be exercised when unpacking to make sure that no parts
are broken or damaged, and an inspection should be made immediately to
check for any in transit. All dust and dirt should be carefully
blown out of the comp te assembly, especially in the closing toggle linkage,
overload attachments and such other attachments as are supplied.
It is not advisable to lubricate any parts of the breaker. The
lubrication supplied during factory assembly, where necessary, is a special
form of grease which is used sparingly. This wil l be found sufficient for
years of service. Additional oil will only promote the accumulation of dust
and dirt. In new installations, the breaker must be carefully protected
from plaster, concrete and other foreign gritty particles that may add
friction to the moving parts in the toggle linkage.
Inspection
Final inspection should preferably be made with the breaker in
its permanent mounting, but if this is impossible, it can be set up rigidly
in a vertical position while the inspection is made.
Rotate the manual operating nandle slowly in a clockwise direc­
tion to move the contacts toward the closed position. Check the movement
of each arc tip through the throat of the "De-ion11 arc interrupting chamber
to make sure that the tips do not rub against the ceramic side plates.
Continue the closing motion until the moving arc t just touch the sta­
tionary arc tips. Check the main contact separation at approximately
5/32
inch, as shown on the two drawings
4-D-2515
and
4-D-8316.
The moving arc
tips of all poles should touch within
l/64
inch of each other. Continue
the handle rotation to the fully closed position and watch the main contact
overtravel as evidenced
by rotary motion away from its stop, adjacent to
the section where the shunt is attached. In the fully closed position, the
gap between the main contact stop and the contact arm should be
3/32
inch
minimum.
Return the manually operated handle to the neutral position and
rotate counterclockwise to trip the breaker. The toggle linkage should
collapse and the moving contact assembly move freely to the full open posi
ti�n.
This is followed immediately by complete resetting of the links in
the toggle mechanism. This resetting operation is accomplished entirely by
gravity. For this reason the links must always be free to move without
friction or binding.
Adjustment of Contacts
The arc tip adjustment should be made as shown on drawings
4-D
and
4-D 16.
There is no adjustment provided for the main con­
tacts, and under ordinary circumstances these main contacts will last the
life of the breaker without repair other than occasional cleaning. Both
main and arcing contacts are a high silver alloy and will neither pit nor
weld under any conditions of short circuit.
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