Polyphase motors have rotor bars shaped to give different speed-torque characteristics.
2.
Several methods of starting a polyphase motor are used.
3.
In this instrument a stationary field coil produces a rotating magnetic field, just like a polyphase motor.
4.
Polyphase motors are simple to construct, are self-starting and have little vibration compared with single-phase motors.
5.
But, if the polyphase motor was not selected and it was desired to use a single phase motor on polyphase service, then multiple machines had their motor and heater loads'balanced'so that any 2 or 3 machines would appear to the electric utility as a balanced polyphase load; in any event the Linotype company would supply whatever drive was necessary, even using kerosene heaters and line-shaft operated machines, in locales without electricity.
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