2-12. Overspeed safety switch.
240 volts. The same A..C voltmeter will indicate
e. A.C. Vohmeter. The A. C. voltmeter (fig. 2-
only the incoming voltage when an external source
1 3 ) indicates the A.C. voltage output of the
of electrical power is used to run the dynamotor-
generator portion of the dynamotor-welder, when
welder; or for the emergency circuits, normally 240
the dynamotor-welder is driven by the truck engine.
volts for the dynamotor-welder and 120 volts for
The output voltage is regulated by the A.C. voltage
the emergency circuits.
adjusting rheostat, a n d the A.C. voltmeter in-
dicates the adjusted voltage, which will normally be