Motors
The DC motor, known as a "Constant speed motor" is the _ motor
Shunt
Armatures are wound to provide high voltage, high current, or some specific combination of voltage and current. The winding that provides moderate voltage and moderate current is the _ wound
Frogleg
A square wave voltage varies between 0V and 12 V. he positive pulses are 50 us wide and there is a 50 us gap between them. What is the DC average of the waveform?
6V
List three basic types of DC motors
1. Series
2. Shunt
3. Compound
A device that converts mechanical input into DC electrical output is a(n)
Generator
A compound motor has _ field windings
Series and Shunt
Armatures are wound to provide high voltage, high current, or some specific combination of voltage and current. The winding that provides low voltage and high current is the _ wound.
Lap
A square voltage varies between 0 V and 12 V. The positive pulses are 75 us wide and there is a 25 us gap between them. What is the DC average of the waveform?
Two factors that determine amount of torque produced by a DC motor
1. Strength of the magnetic field of the pole pieces and armature
2. Strength of the magnetic field of the armature
The component of a DC generator that converts the armature AC into DC is the
The Servomotor which has a fiberglass and copper rotor is the _ motor
ServoDisc
Armatures are wound to provide high voltage, high current, or some specific combination of voltage and current. The winding that provides high voltage and low current is the _ wound
Wave
HP = 2.842125
Eff= 63.10
The amount of CEMF produced in the armature of a DC Motor is proportional to three factors name the 3 factors
1. Number of turns of wire in the armature
2. The strength of the magnetic field of the pole pieces
3. The speed of rotation of the armature
In a generator, the series field diverter is also called the
Series field shunt rheostat
The compound motor connection that is rarely used is the
Differential
When full voltage is applied to the both the armature and the shunt field, the motor operates at
Base Speed
A DC motor is connected to a 240-VDC line and has a current draw of 42 A The motor is operating a load that requires 350 in-lb of torque and is turning at a speed of 1575 RPM
HP = 8.764875
Eff = 64.86
When a DC machine is used as a motor what function does the commutator perform
The commutator performs the function of a rotary switch and maintains the correct direction of current flow through the armature
Permanent magnet motors have _ efficiency than wound field motors.
Higher
In a compound DC motor control circuit, the field loss relay will disconnect the _ if power is lost to the _
Armature, Shunt Field
When full voltage is applied to the armature and reduced current flows through the shunt field, the motor operates at
Overspeed
A DC motor is connected to a 120-VDC line and has a current draw of 5 A The motor is operating a load that requires 40 in-lb of torque and is turning at a speed of 1250 RPM.
HP = 0.795
Eff= 98.845
List two ways to reduce current to the armature of a DC motor.
1. Connect resistance in series with the armature
2. Use an electronic controller to supply voltage to the armature circuit separately from the field
Most converters that supply power to brushless DC motors produce a _ wave
Trapezoidal