The tension in the coupling spring determines the current
at which the dash pot will be mechanically by-passed. This
is the instantaneous pickup adjustment. The high range
instantaneous element has calibrated settings at 7.5, 10 and
15 times the coil and magnet setting.
C.
Selective Service Trip Device (TD-2)
(Long Delay and Short Delay)
The selective
trip device is similar to the
magnetic trip device except that it has a rigid coupling link
in
of
instantaneous pickup coupling spring and it
has mechanical escapement timing device which provides
short delay for hiih values of
and for faults.
The long delay dash pot is identical to that
on the
dual magnetic trip device. The short delay device is
operated by separate
in the series coil and
magnet assembly. It has pickup adjustment range of 5 to
10 times the coil and magnet setting. In addition, the short
delay has
adjustable band with minimum, intermediate
and maximum settings.
MAINTENANCE ADJUSTMENTS
Remove breaker completely from cells before servicing.
A.
Series Coil and Magnet Assembly
The
series coil and magnet requires no maintenance other
than cleaning periodically to
dust and dirt which
may accumulate on bearings and pivots of the magnet
All pivots and bearings are made of nylon and no
lubrication is required.
The entire series coil and magnet assembly may be remov-
ed and replaced in the field by removing the
coil retain-
ing screws and
magnet retaining screws at the
of the pole insulator.
replacing coils, always tighten
the coil retaining screws securely. This is important to pre-
vent overheating and possible failure. Care should be taken
not to damage the coil insulation
B.
Dual Magnetic Overcurrent Trip Device (TD-1)
(Long Delay and Instantaneous Trip)
The circuit breakers are shipped
the trip devices in-
stalled and properly adjusted. It is only necessary to keep
the devices reasonably clean. They are lubricated for the
life of the circuit breaker and
be lubricated again.
It is possible to remove and replace a trip device in the
field.
To Remove a Trip Device
The trip units which
contained in transparent plastic
cases should be removed as units. Remove the two screws
which hold the trip unit to the breaker frame. These
screws
located in the back of the trip unit and can be
removed by reaching in from behind. The connecting rod
which connects
the magnet assembly must be Slipped
off the pin connection at the magnet. The plastic con-
nector and trip finger are then removed fmm the push-rod.
To Install a Trip Device
Insert the
rod in the
hole in the front channel
and
the trip unit to the channel using the two
hex. nuts provided. Run special
nut
down the push rod. Follow it with trip finger on top of
the push rod with spacer between the wings and another
10.32 nut. (Do not tighten it yet.) Install the nylon
turn-buckle and adjust its length
that it is
longer
than is just
to permit the trip device to reset the
magnetic armature against its stop. Install the
buckle
on the armature pin and retain it with E-ring provided.
Adjust the position of the trip
so that the breaker
does not trip when the magnet is closed with
thick
shim in the air gap, and does trip with
thick shim
in the air gap. Tighten the finger and check thii adjustment
again. The trip unit must reset the magnet
the
way until the armature is against the stop.
C. Selective Service Trip Device (TD-2)
(Long Delay and Short Delay)
The maintenance and adjustment of the selective service
trip device is the same as the dual magnetic trip device,
except that the trip finger on the short delay push rod is
installed under the push rod. Care should be taken to en-
sure that the long delay trip finger on top of its push rod
does not interfere with the short delay trip linger which
is installed under its push rod.
