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What is AC commutator motor?
In electric motor: Alternating-current commutator motors. A specially designed series-commutator motor may be operated from a single-phase alternating voltage supply. When the supply current reverses, both the magnetic field and the armature current are reversed. Thus, the torque remains in the same direction.
Does AC motor have commutator?
Commutator and Brushes Commutators and brushes are used on all DC generators and DC motors. They are also used on some AC motors such as the repulsion, synchronous, and universal motors. All generators produce a sine wave, or AC currents when the rotor turns in the magnetic field.
How does an AC commutator motor work?
A commutator is a rotary electrical switch in certain types of electric motors and electrical generators that periodically reverses the current direction between the rotor and the external circuit. It consists of a cylinder composed of multiple metal contact segments on the rotating armature of the machine.
Why do AC motors need brushes?
The field induces a current flow into the shorted armature whose magnetic field opposes that of the field coils. Speed can be controlled by rotating the brushes with respect to the field axis. This motor has superior commutation below synchronous speed, inferior commutation above synchronous speed.
Why commutator is not used in AC motor?
AC commutator motors, like comparable DC motors, have higher starting torque and higher speed than AC induction motors. However, commutator motors are not as maintenance-free as induction motors, due to brush and commutator wear.
What are the types of commutator?
These characteristics have been used to design a number of polyphase commutator machines, but currently only two types are in general use and are made in relatively large numbers : stator-fed and rotor-fed motors with shunt characteristics.
Do any AC motors have brushes?
AC induction motors have no brushes and have a much longer life expectancy. DC motor speed is controlled by varying the armature current, while AC motor speed control is achieved by varying the frequency of the alternating current, often with a variable frequency drive(VFD).