Figure 3-11. Stored-energy manual closing mechanism cont'd

will bow the bar and leave the center arc-quencher

d. With breaker withdrawn and closing springs

loose.

restrained see that all nuts and bolts are in place and

tight. See that no pins or cotter pins have worked out of

g. Examine the contacts (it is necessary to remove

place and that all cotter pins have sufficient spread to

the arc quenchers to properly inspect contacts) they

hold them in place. All mechanism rods and moving

should be clean and bright, free from dust and dirt

parts should be free from binds and the mechanisms

accumulation.

Check the condition of the arcing

should be in good working order.

contacts which open after and close before the main

current-carrying contacts. If they are badly pitted or

e. Operate the breaker several times to check the

burned, it may be necessary to dress or to replace them.

proper functioning of all parts. In general circuit-

Laminated contacts so badly dam aged or burned and

breaker mechanisms require little lubrication. It is

pitted that satisfactory operation can not be obtained

recommended to use a few drops of good grade light

should be replaced.

machine oil at bearing points, and to wipe off any

excess oil with a clean rag. This should be done at

On feeder breakers (AK-2-50) the series

regular inspection intervals.

overcurrent tripping device EC-I is enclosed in a molded

case. It is mounted by three screws and a bracket to the

f. Inspect the arc quenchers, if the barriers are

lower part of the pole unit base.

cracked or eroded to one-half their original thickness

of 3/16 inch, they should be replaced. Removal or

(1) Check trip latch engagement. The gap

replacement of arc-quenchers procedure is:

between trip latch (5, fig. 3-12) and roller (6) of the

reset latch should be 1/64 to 1/32 inch. This adjustment

CAUTION

is made with adjusting screw (7).

Be sure the breaker is open and closing

(2) Turn the adjusting screw (1, fig 3-12) on the

springs are restrained.

See preceding

trip arm (21. The screw should not touch the trip paddle

paragraph 3-5 c.

(3) when breaker is open and the latch is reset but

should have a clearance not exceeding 1 / 32 inch.

(1) Remove the channel-shaped retaining bar

(view B fig. 3-10) by removing two screws and two nuts,

NOTE

one on each end.

Component parts of the overcurrent tripping

(2) Lift the quenchers clear of the movable

devices are not replaceable. Install a new

arcing contacts.

device when parts are worn or damaged. To

replace an EC-I overcurrent device the front

(3)

Replacement is the reverse of (1), (2)

above.

During replacement be careful not to

and rear frames should be separated 'he

overtighten the screws which secure the channel-

breaker must be removed from the drawout

shaped retaining bar. Overtightening the screws

mechanism and put on a work bench

KEY to figure 3-12:

1. Trip paddle adjusting screw

2. Trip arm

3. Trip paddle

4. Trip shaft

5. Trip latch

6. Roller of reset latch

7 Adjusting screw

3-20