GEt-861518
TRIPPING
In
the closed
position,
the breaker's movable
contacts are
held in
by a toggle linkage. The
breaker is tripped
open by
displacing a mechanism latch
which allows this toggle link-
age to collapse. The trip latch is
rigidly fastened to
a
horizon-
tal trip
shaft
running from
left to
right through the
breaker.
In
turn,
the trip shaft
carries
paddles
actuated by the manual
trip
button and the various
other trip
devices
-
overcurrent,
reverse
current, shunt
trip, undervoltage,
open
fuse
lockout.
Viewing
the
breaker
from
the right, rotating
the trip shaft
counterclockwise trips the
breaker; clockwise movement re-
sets the mechanism latch.
In addition to tripping the
breaker, some devices hold
the
breaker trip
free,
i.e.,
prevent
the
contacts from
closing even
though
a closing
impulse
is
applied to the mechanism.
Such
devices are the undervoltage,
bell alarm
and
lockout,
electric
lockout,
open fuse lockout,
and the key
operated locks.
These devices and the drawout mechanism interlocks
must
be in the reset
position
before the breaker can be closed.
Breakers
employed
in
conjunction
with fuse
rollout ele-
ments
should
be
equipped
with
an open
fuse
lockout device
(OFLO).
This
OFLO
is
a special trip device
having three
(3)
shunt trip
elements
(one per phase),
the
coil of each being
connected across
its
corresponding fuse in the
fuse
rollout
unit. Connections are made via the
C secondary disconnect
block on
the
breaker thru the B secondarv disconnect
block
on the fuse rollout
unit.
The
arc
voltage
generated
by a blown fuse activates
its
OFLO shunt trip
coil,
thereby tripping
the breaker and
pre-
venting
single
phase
power
from
being
supplied to the load.
An indicator
on
the
OFLO device signals which fuse is blown.
The
breaker cannot be closed until the
blown
fuse is ac-
knowledged
by
resetting the
OFLO, and
presumably
replac-
ino the
blown
fuse.
MAINTENANCE
INSPECTION
Periodic inspection
of the circuit
breaker
is
recommended
at least
once a
year.
More frequent inspections
are recom-
mended where
severe
load
conditions,
dust, moisture or
other
unfavorable conditions
exist, or
if
the vital nature
of the
load
warrants it.
Always inspect the
breaker after a short-circuit
current
has
been interrupted.
At the time
of
inspection,
the following
checks should be
made
after
the
breaker has been
deenergized:
1. Manually
operate
the
breaker several times, checking
for
obstructions
or excessive
friction.
Manual closing of
an
electrically operated breaker may be
performed
by the fol-
lowing
two steps:
(1)
Install maintenance
crank
(5688386G1)
to the motor
gear
reducer
shaft
on the front right
side of
the
breaker.
Ratchetthe maintenance
crank up and down untilthe springs
are
fully
charged as
indicated
by the distinct
click as
the
prop
is
set and
prevents
any further
charging of
the
closing
springs. After the
prop
is set do not
apply
undue force to
the
maintenance handle.
(2)
Depress the
"Spring
Discharge" lever located under
the horizontal
support on
the
front
frame.
The
springs should
discharge
and
if the latch is
properly
reset,
the breaker will
close.
2. Electrically operate
the
breaker several times
to
check
performance
of
the
electrical
accessories.
3.
Visually
check
the breaker for loose hardware
on
the
breaker
and the bottom of the
comoartment for anv hardware
that
has fallen from the
breaker.
4. Remove
the arc
quenchers
and
inspect
the arc
quenchers
and contacts for breakage
or excessive
burning.
5.
The
performance
of the
solid-state current trip devices
may be
checked
with
a suitable test
set. Check electrome-
chanical
devices for
positive
trip in accordance with
the
in-
structions in Maintenance
Manual.
6. Check insulating
parts
for
evidence of overheating
and
for
cracks that
indicate
excessive
thermal aoino.
LUBRICATION
In
general,
the
circuit breaker
requires moderate lubrica-
tion. Bearing
points
and sliding surfaces should
be
lubricated
at the regular inspection
periods
with a thin film of GE Lubri-
cant
D50HD38
(Mobil
28). Before
lubricating, remove any
hardened
grease
and
dirt from latch
and bearing surfaces
with kerosene. ALL EXCESS LUBRICANT SHOULD
BE
RE-
MOVED WITH A
CLEAN CLOTFI
TO
AVOID
ACCUMULA-
TION OF DIRT
OR
DUST.
On drawout breakers the
contact
surface of
the
disconnect
studs should be cleaned and
qreased
with
GE Lubricant
D50HD38,
14
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