An unexcited single phase synchronous motor

An unexcited single phase synchronous motor is a type of motor that operates on the principle of synchronous rotation. It is called "unexcited" because it does not require a separate excitation circuit to generate a rotating magnetic field. Instead, it relies on the inherent magnetism of its rotor and stator to produce the necessary magnetic field for operation.

Reluctance motor

A reluctance motor is a type of synchronous motor that uses the principle of magnetic reluctance to generate torque. It operates by creating an asymmetrical magnetic field between the stator and rotor, causing the rotor to align with the stator's magnetic field and rotate.

Repulsion motor

A repulsion motor is a type of single-phase AC motor that uses brushes and commutators to create a rotating magnetic field. It operates by repulsion between the stator and rotor, causing the rotor to rotate in the opposite direction of the stator's magnetic field.

Universal motor

A universal motor is a type of motor that can operate on either AC or DC power. It is commonly used in applications where the motor needs to be able to run on different power sources.

AC series motor

An AC series motor is a type of motor that uses a series field winding and an armature winding connected in series. It is commonly used in applications where high starting torque is required, such as in locomotives and cranes.

Explanation

The correct answer for an unexcited single phase synchronous motor is option 'A' - reluctance motor. This is because an unexcited synchronous motor operates based on the principle of magnetic reluctance, which is the opposition to magnetic flux. The motor relies on the difference in reluctance between the rotor and stator to generate torque and achieve synchronous rotation.

In an unexcited synchronous motor, the rotor is made of a material with high magnetic reluctance, such as laminated iron. The stator, on the other hand, has a winding that produces a rotating magnetic field. When the rotor is subjected to this rotating magnetic field, it experiences a torque that causes it to align with the stator's magnetic field and rotate synchronously.

The advantage of an unexcited synchronous motor is that it does not require a separate excitation circuit, making it simpler and more cost-effective compared to other types of synchronous motors. However, it may have lower starting torque and may require some external means to bring it into synchronism before starting.

In conclusion, an unexcited single phase synchronous motor is a reluctance motor, which operates based on the principle of magnetic reluctance and does not require a separate excitation circuit. It is a simple and cost-effective option for applications that require synchronous rotation.

Reluctance motor