TM 9-4940-549-14&P
Operation on External (CITY) Power.
b.
(1)
Place all switches and circuit breakers in the OFF position.
(2)
Set the frequency switch to match the rating of the incoming
power; either 50 or 60 hertz, and place the power selector
switch in the CITY position.
(3)
Connect the external power source (fig. 4-9). The external
power source must be 240 volts.
NOTE
With the selector switch in the (CITY)
position, connect outside source of
3-phase, 240-volt A. C. power to power
receptacle. 240-volt single-phase
power can now be used from R4, R5, and
R6 receptacles. Also, the air compres-
sor, lathe, drill press, and mill may be
operated. Place the control circuit
breaker (fig. 2-5) in the ON position and
press the dynamotor-welder start switch
momentarily. The generator portion of
the dynamotor-welder is now functioning as
a 25 H. P. motor to drive the welder portion.
Check rotation of dynamotor-welder. The cor-
rect rotation is clockwise from the driving
end. To correct the rotation, interchange any
two of the incoming power leads.
(4)
Check the reading of the frequency meter which indicates the
correct frequency of the incoming power. If it is not compat-
ible with the frequency switch setting, set switch correctly.
The AC voltmeter will indicate input voltage. Power is now
available from all terminals and receptacles. The welder is
driven by the synchronous motor.
Operation on EMERGENCY Power.
c.
(1) General. When neither internal nor 3-phase, 240-volt AC exter-
nal power is available, it is impossible to operate the dynamo-
tor-welder or to provide current to the shop set contents. Un-
der these conditions, an external 120volt, single-phase 50-60
hertz current may, if available, be used to furnish power for
limited operation of the shop set components.
(2) Operational procedure.
(a) Make sure all switches throughout the shop set are in the
