Free Nut
"B"
below attachment clevis, and adjust Nuts
"B"
and
"C"
to depress pawl return spring and
pawl until
1/16
to
3/32
( 1.6 -
2.4 mm)
clearance is obtained between tip of pawl
and
ratchet teeth. This
clearance
is
measured during the clockwise rotation of the pawl as its tip is toward the ratchet (power
stroke).
MAl N TENANCE
General
Tho rough, periodic in spec tion i s importan t to sati sfac tory operation . I nspec tion and main tenan c;e
frequency depend s on in stal l a tion , si te, weather and atmospheric condi tion s, e xperience of
operating personnel and special operation re quiremen ts. Becau se of thi s, a wel l -planned and
effective main tenance program depend s l argely on experience and prac tice.
Prior to performing any main tenance work, make certain al l con trol circui ts are open , and tha t
the breaker has been compl e tely wi thdrawn from the me ta l -c l ad uni t.
CAUTI ON
D O N OT WORK ON THE BREA KER OR OPERATI NG MECHA NI SM WHI LE TH E BREA KER I S I N
TH E CLOSED POSI TI ON. D O N O T WORK ON THE BREA KER OR O PERA TOR WHI LE TH.E
CLOSI NG S PRIN G S ARE CHARG ED .
Always i n spec t a breaker which ha s in terrup ted heavy faul t curren t.
Al l curren t carryin g joints should be inspec ted to be sure a l l con tac t surface s are free of p ro
trusion s or sha rp plane c han ge s.
Contact Erosion
A visual check of distance "A" Figure (3) with breaker closed will indicate the contact erosion. When the
distance measures within .030 to .015 inches (.8 to .4mm) the interrupter assembly should be replaced.
Intermediate adjustment is not recommended.
V
acuum
CAUTION!!
OBSERVE THE FOLLOWING ITEMS WHEN HI-POTTING THE VACUUM INTERRUPTERS.
A hi -po t te st should be appl ied to the open in terrupter con tac ts of each p hase. The vol tage
should be rai sed gradual l y, and the con tac t gap should sustain 27k V 60Hz ac , or 38kV d e, for
one minute for each p ha se .
S hock Absorber
The pneumatic puffer-
�
hock absorber assemblies
of
the air-magnetic circuit breaker
mechanism
have
been replaced by
a
hydraulic shock absorber (138, Fig. 4b} and a stop bar {143, Fig.
4b)
on
the
vacuum circuit breaker. The shock absorber should require no adjustment unless an entire vacuum
interrupter assembly is being replaced. However at maintenance checks the shock absorber should be
examined for evidence of leaking. If evidence of fluid leakage is found, the shock absorber must be re-
-13-
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