dynamotor-welder is now used as a 25 H.P. syn-
2-13 ) is used to start and stop the dynamotor-
chronous motor to drive the welder portion. A.C.
welder when an external electrical power source is
power is available at all terminals and receptacles,
used, and also to close the contactor to provide A.C.
as well as D.C. power for welding.
power when the dynamotor-welder is driven by the
(3) In EMERGENCY position, an external
truck engine. To operate the switch, press the
source of 120-volt A.C. single-phase power is
connected to the shop set. The shop set lights and
button momentarily to stop or start.
g. A.C. Voltage Adjusting Rheostat. The rheostat
R3 receptacle on the control panel can be used.
(4) In OFF position, all A.C. circuits are
the generator portion of the dynamotor-welder,
de-energized. When the engine is running at 1,200
from the minimum to the maximum. Turn handle
rpm, the welding studs are energized for normal
welding operations.
clock wise to increase and counterclockwise to
decrease A.C. voltage.
m. Circuit Breaker, Control. The function of the
control circuit breaker (fig. 2-13 ) is to protect the
motor-starting contactor circuit from overloading.
2-13 ) should be set on 60 cycles if 60-cycle external
This circuit breaker is rated at 3 amperes.
power is used to run the dynamotor-welder; or, if
n. 240-Volt Circuit Breakers. These 3 circuit
the engine governor is adjusted so that the truck
engine will run at 1,200 rpm to cause the
breakers (fig, 2-13) protect the three 240-volt,
single-phase receptacle circuits, R4, R5, and R6
d y n a m o : or-welder to develop 60-cycle A.C.
from overloading in excess of 10 amperes for each
current. The switch should be set on 50 cycle if 50-
receptacle.
cycle external power is used, or is the engine
governor is adjusted at 1,000 rpm for 50-cycle A.C.
o. 240-Volt, Single-Phase Receptacles. T h e s e
current
receptacles (fig. 2-13) are twist-lock type and will
transmit a maximum 0f 10 amperes of electric
13) indicates the cycles of incoming power when an
current when t h e g e n e r a t o r p o r t i o n o f t h e
external electrical power source is used, and in-
dynamotor-welder is driven by the engine or an
d i c a t e s the cycles of output power when the
external source of electrical power. Electrical power
dynamotor-welder is driven by the truck engine.
is also available when the external power source is
Normal reading is 60 cycles when the engine is
connected to the shop set and the dynamotor-
driving the dynamotor-welder at 1,200 rpm, and 50
welder is stopped.
cycles at 1,000 rpm.
p. 240-Volt, 3-Phase Circuit Breakers. These 4
j. 120-Volt, Single-Phase Circuit Breakers. The
circuit breakers (fig. 2-13) protect the air com-
circuit breakers (fig. 2-13) protect these circuits
pressor a n d l a t h e e l e c t r i c a l c i r c u i t s f r o m
against overloading which could be connected to
overloading in excess of 30 amperes each. They also
the 120-yolt, single-phase receptacles. These circuit
p r o t e c t the milling a t t a c h m e n t circuit from
breakers are rated at 30 amperes each.
overloading in excess of 15 amperes.
k. 120-Volt, Single-Phase Receptacles. 120-volt,
single-phase power i s available at the three
indicates the amperage of D.C. welding current
receptacles (fig. 2-13), R 1, R2, and R3, when the
only when welding is actually being accomplished.
dynamotor-welder is powered by the truck engine,
The normal reading will vary with the amperage
or by an external power source. Only the R3
range selected at the D.C. ampere selector switch
receptacle wilI transmit 120-volt, single-phase
and the fine adjustment made at the D.C. ampere
adjusting rheostat.
power, when using only 120-volt emergency power.
l. Power Selector Switch. The power selector
is used to direct the flow of D.C. welding amperes
switch (fig. 2-13 ) sets the control panel for the
from the welding rod to the material (straight
source of power that will be used to run the
dynamotor-welder and/ or the shop set,
polarity) or to direct the flow of amperes from the
material to the welding rod (reverse polarity). The
(1) In GENERATOR position, the
norm al position of this switch could be different for
dynamotor-welder is driven by the truck engine.
each welding job based on many elements that only
The generator portion of the dynamotor-welder will
experience will predict. The switch must be OFF
produce A.C. current regulated by the A.C. voltage
when welding is not being performed to prevent
adjusting rheostat. Power is available at all ter-
possible damage.
minals and receptacles. D.C. current up to 300
amperes and 40 volts is available for welding.
2-13) is used to select the welding ampere range
(2) In CITY position, an external source of
240-volts A.C. 3-phase power is connected to the
r e q u i r e d for all welding to be accomplished.
Amperes lower than 30 are available for special
input receptacle. The generator portion of the
