unit 18 multiple choice

75

A brush-lifting motor uses a radial commutator, and weights are mounted at the front of the armature. When the motor reaches about ____% of full speed, these weights swing outward due to centrifugal force and cause two push rods to act against a spring barrel and short-circuiting necklace.

120 or 240 volt

Many split-phase motors are designed for operation on ____.

centrifugal

Motors that are not hermetically sealed use a ____ switch to disconnect the start windings from the circuit.

two to five

Multispeed fan motors have been used for many years and are generally wound for ____ steps of speed and operate fans and squirrel-cage blowers.

synchronous

Single-phase ____ motors operate on the principle of a rotating magnetic field developed by a shaded-pole stator. Although they will operate at synchronous speed, they do not require DC excitation current.

electrical impulses

Stepping motors are devices that convert ____ into mechanical movement.

first started

The direction of rotation for a split-phase motor is determined by the direction of rotation of the magnetic field created by the run and start windings when the motor ____.

frequency

The speed of a shaded-pole induction motor is determined by the same factors that determine the synchronous speed of other induction motors—____ and number of stator poles.

run

The stator of a split-phase motor contains two separate windings, the start winding and the ____ winding.

induction-run

There are three basic repulsion motors: repulsion motor, repulsion-start ____ motor, and repulsion-induction motor.