Meters (Voltmeter and Ammeters)

tween the moving contact and the moving contact

i. The main breaker (AK-3-50) has a power sensor

support. If there is no opening, it indicates that the parts

overcurrent trip device. When malfunctioning of the

of the contact support that bears on the cam or the cam

power sensor trip is indicated notify direct support

itself has become worn. Sometimes it is possible to

maintenance.

secure a temporary repair by bending the moving

j. Racking in a Circuit Breaker.

contact so it has a smaller separation from the fixed

(1) Push the breaker into the compartment until

contact when in the open position.

the "test" position stop engages to prevent further travel.

(view C fig. 3-10)

3-18. Potential and Current Transformers

(2) Depress the test stop (view D) lever and

push circuit breaker back into compartment until the

Transformers need no care other than keeping them

racking pins on the housing butt against the outer

clean and dry and connections tight.

surface of the racking cam.

(3) Raise the racking handle (view E) this

stroke tip causes racking pin (view A) on housing to

3-19. Fuses

engage the trip interlock link and pin assembly, rotating

the link (view A) and causing the pin (view A) to remove

a. General. There are two circuits fused; the

upward against the adjusting screw on the interlock trip

potential transformer circuit with three 6 amp, 600 volt

paddle. This trips the breaker and holds it tripfree

cartridge fuses and the 115 volt circuit serving the

during the entire racking operation.

heaters, lights and an outlet. This circuit has one 20

(4) Push racking handle down and repeat this

amp fuse. Both fuse blocks are mounted on the inside

four more times (5 complete). The fifth and final stroke

of the right rear door near the top. Always replace blown

releases the trip interlock and allows breaker to be

fuses with the recommended fuse ratings.

closed.

b. Replacement of potential transformer fuses (2.

fig. 2-16).

3-16. Meters (Voltmeter and Ammeters)

(1)

Fuse block is a molded black totally

enclosed case.

(2) Using handle pull the fuse block from the

If the meters have broken cover glasses, damaged

case.

cases or pointers or are not operating, they must be

(3) Replace the blown fuses (6 amp 600 volt).

replaced . Report to organizational maintenance.

(4) Push fuse block back into case.

c. Replacement of 115 volt circuit fuse (3, fig. 2-

3- 17. Voltmeter and ammeter Selector Switches

16).

fig. 2-9)

(1) Fuse block is an expose cartridge clip for

a. Remove the cover of the switch by loosening the

two fuses.

captive screw on the back.

(2) Replace blown fuse (only one in circuit).

b. Inspect for burning of the contacts, broken shunts

on the moving contacts and for contact wipe.

3-20. Heaters (fig. 1-3) (8, fig. 2-16) and (2, fig.

c.. If the shunts are broken or the contacts badly

2-17)

pitted, the switch should be replaced.

d. Contacts have sufficient wipe as long as there is

Check that heaters are secured tight and the

an appreciable opening, with the contact, be-

connections are tight.

Section VIII. MAINTENANCE OF ACCESSORIES

3-2 1. General

3-23. Handrails

Instructions contained in this section are for operators

a. Inspect the post for straightness, scratches and

information and guidance in maintenance of the

digs. Clean and repaint where needed.

accessories.

b. Inspect the chain for breaks and that the snap

hooks are working.

3-22. Storage Cabinets

3-24. Lifting Slings

a. The external and internal surfaces should be

inspected regularly. If they show signs of

a. Inspect each sling for bad kinks or bends, broken

weathering, scratches, digs or are dirty, the surfaces

strands, hook and eye splices are intact.

should be cleaned and repainted where needed.

b. If there are defects in the slings they should be

replaced.

b. The hinged top should work smoothly and close

properly. If it or the hinges are bent and cannot be

corrected by the operator, he should report this for

future repair.

3-22