A DC motor with a constant field voltage increases its speed when the voltage across its armature circuit increases, and vice versa. Above the motor’s base speed (maximum rated speed with rated load, armature, and field voltage), speed can be increased by reducing field voltage.
How does the drive change the speed of a motor?
An ac drive is a device that is used to control the speed of an electric motor. The speed is controlled by changing the frequency of the electrical supply to the motor. The three-phase voltage in the national electrical grid connected to a motor creates a rotating magnetic field in it.
What is the disadvantages of DC drive?
The disadvantage of D.C. drives is the presence of a mechanical commutator which limits the maximum power rating and the speed. … The variable speed applications are dominated by D.C. drives because of lower cost, reliability ad simple control.
What determines speed of a DC motor?
DC controls adjust speed by varying the voltage sent to the motor (this differs from AC motor controls which adjust the line frequency to the motor). Typical no load or synchronous speeds for an AC fractional horsepower motor are 1800 or 3600 rpm, and 1000-5000 rpm for DC fractional hp motors.
What determines the speed of a motor?
The rotating speed of an electric motor depends on two factors: its physical construction, and the frequency (Hz) of the voltage supply. Electrical engineers select the speed of a motor based on the needs of each application, similar to how the mechanical load determines the horsepower required.
Which one of the following motor is a 1 φ AC motor?
1. Which one of the following motor is a 1-Φ AC motor? Explanation: Capacitor run motor is a 1-Φ AC motor. The capacitor is used to provide a 90° phase difference between the currents of main and auxiliary winding.
Which motor is used for variable speed?
For applications where variable speeds are necessary, typically an AC motor with an Inverter or brush motors are used. Brushless DC motors are an advanced option due to their wide speed range, low heat and maintenance-free operation. Stepper Motors offer high torque and smooth low speed operation.