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FOR MANAGERS AND OPERATORS 387
Next move lever of starting box slowly to right as machine speeds up, until it finally reaches the last contact, where it will be caught and held by the cut-out magnet. By this time the armature will have reached maximum speed.
The field rheostat of the generator field circuit is marked with a small white arrow to indicate proper position it should occupy for machine to deliver the current and voltage at the arc as shown on generator name plate.
To Start Arc. — When the armature is up to speed, arc may be struck as follows: Close projection machine switch and bring carbons of lamp together, instantly separating them again about one-sixteenth of an inch, gradually increasing this distance as the carbons heat up until the proper length of arc to supply maximum screen illumination is reached, whereupon the voltmeter should register about 55 volts at the arc and the ammeter about 35 amperes, where the 35 ampere set is used, or 55 volts at the arc and 50 amperes if it is a 50 ampere outfit.
Caution. — The closing of the carbons short circuits the generator, and, of course, instantly creates an overload. The generator is wound to protect itself against this very thing, and unless the carbons are instantly separated the generator will lose its voltage This does no harm to the machine, but it will be necessary to separate the carbons for perhaps ten seconds until the voltage again reaches normal, zvhereupon the arc may be struck in the usual manner.
As the machine warms up it may be necessary to move the handle of the rheostat one or two buttons away from the mark, to the left, in order to maintain the desired voltage and amperage at the arc.
Reversing Connections.— Provided the circuits have been connected as shown in the diagram the polarity will be as indicated, and the upper carbon of the lamp will be positive. Should an error be made in connections, and either or both the voltmeter and ammeter read backward, the trouble must be corrected. Examine all diagrams and see that all connections are made in accordance therewith, particularly that the motor terminals are connected to the proper side of the line. Do not attempt to correct trouble by reversing the terminals at the generator. The machines are all carefully checked up complete with their equipment when tested, and