Rotor

Definition

The rotor is the rotating part of an electric motor, generator, or transformer. It is the component that converts electrical energy into mechanical energy or vice versa, depending on the device's function.

5 Must Know Facts For Your Next Test

1. The rotor is the key component that enables the conversion of electrical energy to mechanical energy in a motor, and mechanical energy to electrical energy in a generator.
2. The rotor's design and construction, such as the number of poles and the winding configuration, determine the motor's or generator's performance characteristics.
3. In a transformer, the rotor is replaced by a secondary winding that is magnetically coupled to the primary winding to transfer electrical energy between the two circuits.
4. The rotor's speed is determined by the frequency of the alternating current (AC) supplied to the motor or the number of poles in the stator.
5. Proper maintenance and balancing of the rotor are crucial to ensure efficient and reliable operation of electric motors and generators.

Review Questions

• Explain the role of the rotor in the operation of an electric motor.
  • In an electric motor, the rotor is the rotating component that converts the electrical energy supplied to the motor into mechanical energy. The rotor is typically made of a conducting material, such as copper or aluminum, and is wound with coils. When an electric current is applied to the rotor, it creates a magnetic field that interacts with the magnetic field of the stator, causing the rotor to spin and produce torque. The speed of the rotor is determined by the frequency of the alternating current (AC) supplied to the motor or the number of poles in the stator.
• Describe the function of the rotor in a generator.
  • In a generator, the rotor is the rotating component that converts mechanical energy into electrical energy. The rotor is typically made of a conducting material, such as copper or aluminum, and is wound with coils. When the rotor is spun by an external mechanical force, such as a turbine or a reciprocating engine, the rotating magnetic field of the rotor induces a current in the stator windings, generating an electrical output. The design and construction of the rotor, including the number of poles and the winding configuration, determine the generator's performance characteristics, such as voltage and frequency.
• Analyze the role of the rotor in a transformer and how it differs from its function in motors and generators.
  • In a transformer, the rotor is replaced by a secondary winding that is magnetically coupled to the primary winding. The transformer does not have a rotating component like the rotor in motors and generators. Instead, the transformer relies on the principle of electromagnetic induction to transfer electrical energy between the primary and secondary windings. The primary winding creates a varying magnetic field, which induces a voltage in the secondary winding. The absence of a rotor in a transformer means that it does not convert between electrical and mechanical energy, but rather it is used to change the voltage or current levels between two electrical circuits.

Related terms

Stator:

The stationary part of an electric motor, generator, or transformer that surrounds the rotor and creates a rotating magnetic field to induce current in the rotor.

Armature:

The part of an electric motor or generator that carries the main current and interacts with the magnetic field to produce torque or voltage.

Commutator:

A device that reverses the direction of current flow in the rotor of a DC motor or generator, allowing the conversion between electrical and mechanical energy.