Motor 2 Flashcards
A wound-rotor motor delivers higher ? than a squirrel-cage motor without creating an overload of the electrical system.
Starting Torque
The rotor windings of a wound-rotor motor circuit are not short-circuited while starting; whereas the rotor windings of a squirrel-cage induction motor are always short-circuited.
True
Note: When all the resistance is removed from the rotor circuit, the last contact shorts the rotor windings and the rotor is a squirrel-cage with a copper winding.
A permanent split-capacitor motor is also known as a ? motor.
Capacitor-Run
A ? switch removes the capacitor and start winding from the circuit after the motor accelerates in a capacitor-start motor.
Centrifugal
When the dual voltage single-phase motor is reconnected for the higher voltage (115 volts to 230 volts), the current is ? .
Reduced by half
Note: This is due to the fact that the stator coils are reconnected from a parallel circuit into a series circuit, increasing the impedance by four while the voltage is cut in half.
Fuses and circuit breakers (CBs) are used for ground-fault and short-circuit protection; overload relays are typically used for overload protection.
True
A ground fault is an unintentional connection between an ungrounded conductor and any grounded raceway, box, enclosure, or fitting.
True
An OCPD must be used to provide protection from short circuits and ? .
Ground Faults
DC shunt motors can develop about ? to ? of full-load torque upon starting
250%/300%
DC compound motors have shared characteristics of series motors and shunt motors.
False
A DC ? operates on the principle that voltage is induced in a coil of wire when the coil is rotated in a magnetic field.
Generator
The function of a(n) ? is to keep armature windings in the correct polarity to interact with the main fields of a motor.
Commutator
