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A D J U S T M E N T S
33
CONTACTS
Adjustment of Cam Contacts
1 .
The lower contact strap should be formed
at point
A
(Figure 41) to provide proper tension.
At the factory these straps are adjusted so that a
force of 160 plus or minus 10 grams (approxi-
mately 6 02.) applied at the tip of the lower strap,
point
B,
will just close the points.
This tension
must be maintained accurately to avoid a bouncing
condition.
2.
Place shims beneath the plunger stop plate
as required to obtain .040" to .O5O" travel of the
plunger before latching up occurs. If the contact
plunger is overlapped by the latch by an amount
equal to the thickness of the latch metal, this
should provide the .040" to . O 5 O U travel (Figure
42).
Place
5
:
shims
here
,040". , 0 5 0
Latch
Figure 42. Circuit Breaker Adjustment
3.
Place shims between the lower contact ter-
minal block and the contact strap to provide .O15"
to .018" air gap between the contact points (Fig-
ure 43).
4.
Check to be sure that the plunger does not
bind. The design of the split bushing is such that
the coil spring spreads the bushing to create a drag
between the bushing and frame which increases
the pressure required t o close the contact from 160
Place
shims
here
A -
u
Figure 43. Circuit Breaker Adjustment
grams (pressure required to compress the spring)
to 22 5 grams (approximately
8
02.). This friction
is used to dampen the rebound when the contact
closes. Check to be slure that a maximum of 240
grams applied to the plunger will close the con-
tact (Figure 44).
5.
A
pressure of 600 ~ l u s or minus 20 grams
(approximately 21 02.) on the contact plunger
should
be
required to compress the plunger spring
to the latching point (Figure 4 5 )
.
These values
have been tested and found to ~ r o v i d e a good oper-
ating condition.
225
f
15
Grams pressure
lo close contact
Figure 44. Circuit Breaker Adjustment
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