test 2
whats one horse power equal
745
The servomotor which has a fiberglass and copper rotor is the _____ motor
ServoDisc®
How can a Dc motor be made to operate at its base speed
When full voltage is applied to both the armature and shunt field
How can DC motors be made to operate above its base speed
When full voltage is applied to the armature and reduced voltage is applied to the shunt field
Principle of operation of a dc motor
attraction and repulsion of magnetism
What is emf.
back voltage
The motor that does not contain a wound armature, commutator, or brushes is the _____ motor.
brushless
The output voltage of the series generator is set when the load is
connected
Series field windings are connected in series with the armature. They are wound with _____ turns of fairly _____ wire.
few, large
The output voltage of a shunt generator is usually controlled by the amount of
field excitation current
Function of a commutator in a dc motor
mechanical rectifier to change ac produced in the armature to dc
Some DC servomotors have square wave input voltage. To vary the motor speed, the on and off time ratio of the square wave is varied. This is called _____ modulation.
phase
what type of motor should never be operated at no load
series motors must never be operated under a no load motors
In a compound DC motor control circuit, the field loss relay will disconnect the _____ if power is lost to the _____.
shunt field, armature
what type of motor is known as a constant speed motor
shunt motor
What is CEMF.
the induced voltage is opposite to the applied voltage
3 factors that determine the amount of CEMF produced in the armature.
the strength of magnetic field to pole pieces the numbers of turns of wire in the armature the speed of the armature
what two factors determine the amount of torque developed by a dc motor
the strength of the magnetic field of the pole pieces the strength of the magnetic field of the armature
Counter-electromotive force (CEMF) and back-EMF are names for the voltage induced into the armature of a DC motor.
true
what is a motor
turns electrical energy into mechanical energy