Construction; Cross-Sectional View Of Series Overcurrent Tripping Device; With Long Delay And Instantaneous Elements - Westinghouse DB-50 Instructions Manual

Page 14
Fig.
can readily be moved upward to check the
tripping action. The trip plunger extends
out the top of the tripping device and has a
neck and head under which a forked tool can
be engaged to lift the trip plunger against
the trip screw. Close the breaker and move
the trip plunger upward being careful to keep
hands and face clear of parts which move
when the breaker trips.
screw until the trip plunger moves it just
far enough to trip the breaker. Repeated
trials may be necessary.
the breaker before each trial so that normal
latch lap will always be used.
justment , which gives just enough travel of
the trip bar to trip the breaker, has been
found, add the standard overtravel which is
one-half turn of the trip screw downward.

Construction

The overcurrent tripping device is air de­
layed with all of its elements completely
adjustable. A typical unit is shown ready
for mounting on a circuit breaker pole unit
in Figure 4.
1 .... .. ... ..
6
-

Cross-Sectional View of Series Overcurrent Tripping Device

with Long Delay and Instantaneous Elements

Adjust the trip
T rip and close
When ad­
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The tripping device consists of two main
subassemblies namely:
1 . The magnetic frame and coil assembly
as shown in F igure 5A .
2 . The delay elements assembly as shown
in Figure 5B. The two assemblies are held
together by means of the two white mounting
screws as seen from the bottom of the cali­
bration case.
As seen from the sectional view F igure
6, the magnet frame and coil assembly
consists of a yo. k e , a coil , a stationary and
moving core together with their necessary
insulation.
The delay elements assembly as seen
from the same figure contains an air cham­
ber , a diaphragm , and trip plunger as well
as all the armatures, springs, and valves
to produce the adjustable long delay, short
delay and instantaneous characteristics of
the circuit breaker tripping curve.
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