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
c. Disconnect the wires on the transformer. Make
sure wires are identified and tagged so that they may be
reconnected to proper terminals.
d. Loosen and remove mounting screws and tran-
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:
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.