Section IV. TRANSFORMERS

the trip interlock and allows the breaker to be closed,

the compartment sides to engage the semicircular slot in

the racking cam (fig 5-11). In this position the breaker is

since the breaker is now fully racked in.

ready to be fully racked-in by operating the racking handle

which causes the pin on the compartment side to engage

c. Adjustments. One adjustment on the trip interlock

the trip interlock link and pin assembly. Rotating the link

is required with the breaker mechanism in the reset

and causing the pin to move upward against the adjusting

position and the racking cam not engaging the racking

screw on the interlock trip paddle. This trips the breaker

pins of the compartment. There should be at least 1/8

and holds it trip-free during the entire racking operation.

inch clearance between the top edge of the trip interlock

The fifth and final stroke of the racking handle releases

pin and the adjusting screw on the interlock trip.

Section IV. TRANSFORMERS

5-19. POTENTIAL Transformer Replacement

b. Remove the protective screen around the

transformers.

a. Open

the

hinged

voltmeter

instrument

c. Disconnect the wires on the transformer. Make

compartment.

sure wires are identified and tagged so that they may be

reconnected to proper terminals.

WARNING

d. Loosen and remove mounting screws and tran-

former.

All electrical power should be disconnected.

e. Install new transformer in reverse order.

Otherwise serious bodily injury may result.

Section V. BUSSES

b. After the contacts are cleaned they should be

5-20. Replacement of Busses

coated with a contact lubricant.

To replace a bus, unbolt section to be replaced and install

c. Bolt bus bars together using the following torque's

new section to be replaced. Install new section in reverse

order after taking the following precautions:

for tightening:

a. Clean all silvered contacts with silver polish. Do

3/ 8"-16 bolt torque to 15-20 ft-lbs.

not use sandpaper or any other type of abrasive material.

1/ 2"-13 bolt torque to 30-40 ft.-lbs.

Be sure all polish is removed after leaning.

5/ 8"-11 bolt torque to 35-45 ft.-lbs.

Section VI. WIRING

diagram in TM 5-6120-250-12, and heater and light circuit

5-21. Replacement of Wiring

and connection diagram (fig.5-12).

All internal wiring is contained in covered wire troughs.

Replace

ire

according

connection

5-16