What is a Shaded Pole Motor : Construction, Working & Its Applications

Hi guys, welcome to the new post. Here we will discuss what a shaded pole motor is. Construction, Working & Its Applications A shaded pole motor is a single-phase induction motor, and a rating of less than 0.05 HP is common since it has a simple structure. This motor is a self-starting motor with one pole shaded with a copper ring. It is a simple, low-cost, and low-maintenance motor. So let’s get started with What is a shaded pole motor?

Shaded Pole Motor Definition

• The shaded pole motor is a type of AC single-phase motor. The shaded pole motor is a small motor having two of four poles that come with an auxiliary winding composed of a copper ring or bar covering a part of every pole for the generation of a weak magnetic field.
• If a single-phase AC supply is connected with stator winding, and due to shading to poles, a rotating magnetic field is produced.
• Auxiliary single-turn winding is known as a shading coil.
• Current produced in this winding through the magnetic field generated a 2nd electrical phase with a delaying phase of magnetic flux varying for the pole, which has features to offer a 2-phase rotating magnetic field.
• The direction of rotation is due to the unshaded side being to the shaded side of the pole. As the phase angle between the shaded and unshaded part is small, the shaded pole motor generated a small starting torque as compared to the torque for full speed.
• Shaded pole motors of the asymmetrical type are reversible by disassembly and flipping over the stator, though some of the same motors come with small, short auxiliary windings of thin wire and thick copper bars and can be reversed electrically.

Shaded Pole Motor Construction

A Shaded Pole Motor comes with these main components:

Stator:

• The stator comes with primary poles that normally have 2 to 4 poles that come with their own exciting windings. Each pole part of the core is configured with a copper coil, making a closed loop that is called a shading coil. The laminated poles come with slots that are cut across the lamination of the pole. Slots are configured 1/3 of the way from the edge of the pole. Short circuit copper is configured in slots, making part of it shaded poles and the remaining part of the pole unshaded.

Rotor:

• This motor comes with a squirrel cage rotor. Rotor bars are configured at an angle of 60 degrees in slanted form. A slanted structure is made for optimizing torque and reduces dip at the acceleration phase.

End Rings:

• These are short-circuited rings configured at both rotor ends.

Main winding:

• The main winding is the primary winding of the motor. Here, the power source is connected.

Shading coil:

• It is a single-turn copper ring or bar placed around each pole of the stator. It is attached to the main winding through a capacitor.

Capacitor:

• The capacitor is used to delay the current in the shading coil, which results in the magnetic field produced by the shading coil rotating slower than the magnetic field of the main winding.

Working Principle of Shaded Pole Motor

• When the supply is connected with the main winding, a field is produced in the stator.
• The shading coil is connected with an asymmetrical structure over the pole face. It causes part of the pole to be more magnetically conductive than the rest state.
• When AC volts change, the shading coil induces an eddy current in the shaded part of the pole, which causes a small time lag in field creation.
• This time lag field is not properly configured with a pole, generating a rotating field.
• The rotating field interacts with the rotor and starts moving in the direction of the rotating field.

Working of Shaded Pole Induction Motor

The working principle of a shaded pole induction motor is simple. If single-phase AC is given to the stator winding, it generates a stator magnetic field. This magnetic field connects the shading rings. As a result, EMF is induced in shading rings.

Shading rings are created with highly conductive materials, copper, and make closed loops.

The current started moving in a shared ring due to induced EMF. This circulation current also generates a magnetic field that hinders the magnetic field. As a result, there is space displacement created in the shaded part and the unshaded part of the motor.

The space displacement between the main field and the shaded field is at 90 degrees.

Motor-generated rotating magnetic field since time and displacement between the main field and shaded part field. The rotating magnetic field rotates from the unshaded part to the shaded part of the motor.

As a result, starting torque is produced due to the rotating magnetic field.

Shaded pole motor diagram

Here is a diagram of a shaded pole induction motor:

It has two poles on the stator, and each stator has a main winding and a shading winding.

The main winding is connected with the power source, and the shading winding is connected with the main winding through the capacitor.

The rotor in the motor is a squirrel-cage type. This rotor is made with the use of copper bars in a series combination that is short-circuited at the ends.

If the motor’s stator field induces a current in the rotor bars. Current-generated fields connect with the start field and rotate the rotor.

Why Is It Called a Shaded Pole Induction Motor?

It is called a shaded pole since a single-phase induction motor comes with salient or projected poles.

These poles are shaded with a copper band or ring that is inductive. Poles are divided into two unequal halves. The smaller part has a copper band and is known as the shaded portion of the pole.

Shaded Pole Induction Motor of Characteristics

• Its construction is simple and easy to design.
• It has a low starting torque and power factor.
• its features are that no reverse of direction is possible
• It is a less costly motor.
• It is a self-start motor.
• It is a small size, about 40 watts or less.

Applications of Shaded Pole Induction Motors

• It is used in devices that need low starting torque.
• It is used in exhaust fans, table fans, etc.
• This motor is used for starting an electronic clock.
• It is used in refrigerators and air conditioners for driving cooling mechanisms.

Why is the shaded pole induction motor suitable for low power rating?

Shaded poles are used for power applications due to low starting torque and efficiency ratings. Due to less starting torque, shaded poles are made in small sizes from 1/20 to 1/6 hp.

types of induction motors.

How does the rotating magnetic field produce in a shaded pole induction motor?

Due to excitation current produced in shading winding. The field from the shading winding current is in quadrature to the excitation. It rotates the field in from the middle of the pole to the shaded edge of the pole, causing the rotating field to pull the rotor round.

Advantages of Shaded Pole Induction Motor

• Self-starting:
• Simple design:
• Low cost:
• Rugged and reliable:
• Low maintenance:

Disadvantages of Shaded Pole Induction Motors

• It has a low starting torque.
• There is no reverse rotation in this motor.
• It has a poor starting power factor.
• Its efficiency is low.

What is Synchroscope, Working, Features & Applications

Introduction to Synchronous Motor, Working, Types, Construction, Advantages & Applications

Difference between Induction Motor and Induction Generator

Synchronous motors vs. shaded pole motors

The shaded pole motor is a single-phase motor. Shaded winding is a technique for starting a single-phase motor.

The synchronous motor is a complex polyphase motor with a round rotor getting power with DC through slip rings that are from the exciter moving on the shaft.

The exciter is used as a DC motor to wind the synchronous motor up to speed, and then the starter makes a connection with the supply, and the excitation circuit closes.

Faqs

• What is a shaded pole motor?

The shaded pole induction motor is a single-phase AC electric motor used for simple and reliable design. These motors are used in fans, refrigerators, and some small pumps.

• What are the advantages of shaded pole motors?

It is self-starting, a motor without the use of an extra starting process. It is best for small devices.

Less maintenance needed and highly reliable. It is less weight and compact size.

• What is a capacitor and shaded pole?

A capacitor is a device that stores electrical energy.

A shaded pole motor is a type of AC single-phase induction motor, also called a single-phase induction motor. It is just connected with a single voltage line and an external capacitor needed to run the motor.

• Which of the following are the features of a shaded pole motor?

• It generated starting torque that is half of the torque on full load.
• It is less efficient due to power losses in the shading coil.
• It is used in small devices such as fans.
• Based on shaded coil position direction, rotation varies.

• What is the principle of a shaded pole?
• If power is connected to the stator, flux in the main part of the pole induces a voltage in the shading coil, which works as a transformer secondary winding. As the current in the secondary winding of the transformer is out of phase with the current in the primary windings

• What is the efficiency of a shaded pole motor?

The efficiency of shaded pole induction motors is low, in the range of five to 35 percent. Its efficiency is low due to power losses in the shading coil.

• What is the disadvantage of a shaded pole motor?

It has low efficiency with constant power losses in the shading coil.

It has limited torque that makes it not good for heavy loads.

It is not able to reverse the direction of rotation without modification of design.

its less power factor-limited uses.

• Does a shaded pole motor have only one winding?

This motor comes with a single winding with no capacitor or starting winding switch, making it reliable and less ess costly. Larger and latest types can come with multiple windings, but electrically they have one, and a capacitor can be used.

• What is the direction of a shaded pole motor?

The direction of rotation from the unshaded side to the shaded side of side of the pole. As the phase angle between the shaded and unshaded parts is small, shaded pole motors generate small starting torque relative to torque at full speed.

• How many windings does a shaded pole motor have?

A shaded pole motor comes with a main winding connected with a single-phase supply. With that, it has a permanently short-circuited winding ahead of the main winding in the direction of rotation. That 2nd winding is called a shading coil.

• Why is the efficiency of a shaded pole motor low?

It has less efficiency due to power losses in shading winding.

• Will a shaded pole motor rotate?

A shaded pole motor rotates in one direction, and reverse motion of the motor does not does not exist. The direction of rotation of the magnetic field is from the (unshaded) pole to the shaded pole.

• Are shaded pole motors synchronous?

A shaded pole motor is a single-phase motor; shaded pole winding is starting a single-phase motor. The synchronous motor is a complex polyphase motor with a wound rotor fed with DC slip sings from an exciter that operated on the shaft.

• What is the function of a shaded pole induction motor?

In a shaded pole induction motor, the shaded winding generates a weak rotating magnetic field and not a constant magnitude. So these are small ratings of 20 watts. This motor can be used for toys, hair dryers, fans, etc.

• Why do motors have to reverse pole direction?

As the magnetic field winding is pushing or pulling the magnet on the spindle, the motor reverses direction when the current reverses. According to Faraday’s left-hand rule, if the magnetic field direction changes, then the direction of the force changes.