Electrical Tripping; Inserting Safety Pin; Inspection; Maintenance - GE AK-2-50 Maintenance Manual

ELECTRICAL TRIPPING
-
The breaker may be tripped electrically by any
of tha electrical tripping devices described in
these instructions. . The breaker may also be
tripped by the automatic overcurrent or reverse
current tripping devices,
if
so equipped. All
these devices trip the breaker inasimilarmanner,
i.e. ·the device trip arm moves against the trip
paddles fastened on the trip shaft, thus rotating
the trip shaft and displacing the trip latch.
The most commonly used tripping device is the
shunt trip device connected in the control circuit
as shown in Fig. 1. When a tripping signal is given,
the shunt trip coil is energized through a nortrlally-
open auxiliary switch " a" - contact, thus tripping
· tbe breaker.
.
.
MAINTENANCE
BEFORE INSPECTION OR ANY MAINTENANCE
WORK IS DONE BE SURE THAT THE BREAKER
IS IN THE OPEN POSITION. ALL ELECTRICAL
POWER, BOTH PRIMARY AND· CONTROL
SOURCES, SHOULD ALSO BE DISCONNECTED.
Warning: On breakers employing stored-en-
ergy closing mechanisms, care must be taken
when the circuit breaker is being installed
and when any inspection or maintenance work
is being done so that the breaker is in the
open · position and the closing springs are
· being re15trained by the safety pin. The proce-
dure for inserting the safety pin is given below.
- INSERTING SAFETY PIN -
AK-50 , - 75 and -100 ·
. (Fig •. 3) . .
The closing sprini ~hould be charged with the
maintenance handle (1) so that the safety pin (3) -
can be placed
in
the hole of the push rod (2).
Continue to op er. a te the maintenance· handle, clos-
ing the breaker. This is done so that the safety
pin takes the SJ?ring force.
- To il)stall the safety pin of the manµal stored-
energy mechanism refer to the section entitled
STORED - ENERGY MANUAL MECHANISM
on page
17 of these instrucUons.
With the safety pin restraining the closing
spring force, the. contacts will close s. l owly when ·
the breaker is manually operated a1lowing the
operation of the mechanism and the contact align-
ment ~o be visually observed.
.
.
-
. !allowing the inspection period, the closing
sprmgs must be recharged, the safety pin removed
from the push rod, and the pin placed in the retain-
ing spring clip adjacent to the push rod.
Low Voltage Power Circ~it Breakers GEK-7303
Fig. 3 {8039670) View showing operation of
· AK-2-50 ·breaker with manual maintenance
handle and installation. of safety pin,
1. . Manual maintenance 'Handle
2. Push Rod
3. Safety Pin
INSPECTION
Periodic inspection of the circuit break~r is
recommended ·at least once a year. · More fre-
quent inspections are recommended
if
severe
load. conditions, dust, moisture or_ other unfavor
able conditions exist. A complete inspection
.of the breaker, including contacts and arc quenchers,
should always be made after the breaker has in-
terrupted a short-circuit.
At regular inspection periods the breaker should -
be operated manually; (stored energy mechanisms ·
with the safety pin restraining the closing spring
force)
fo
observe the contact alignment and to
make sure all mechanism parts move freely
without binding or excessive friction.
If
the breaker remains -open or closed for a·
period of six months or more, it is recommended
that arrangements . be made to open and close it
several times in succession, . preferably under.
load.
If overheating, not caused by overcurrent, is
observed, a complete inspection of the breaker
should be made including connections and contacts.
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