Hi guys welcome to the new post. Here we will discuss What is a Shaded Pole Motor : Construction, Working & Its Applications A Shaded Pole Motor is a single-phase induction motor that is mostly used in low power consuming applications where simple and cost-effective motors are needed. Its name is given by the shading coil design which makes the rotating magnetic field in the motor help to operate it. Here we will cover different parameters of shaded pole motors and related parameters. so let get started with What is a Shaded Pole Motor
Shaded Pole Motor Definition
A shaded pole motor is a simple, single-phase induction motor that comes with a rotating magnetic field produced by a winding and shading coil. A shading coil is a single winding copper ring or bar that is configured about the part of each pole of the stator. When current passes through the main winding it produces a magnetic field that rotates around the stator. When current passes through the main winding it causes a magnetic field that rotates around the stator. This delay results in the magnetic field generated by the shading coil moving slightly slower speed than the magnetic field generated by the main winding. The difference in speed of two magnetic fields produces rotating torque which starts the motor.
Shaded Pole Motor Construction
A Shaded Pole Motor comes with these main components:
- Stator: The static part of the motor comes with a main winding and shading coil. The shading coil is a small copper coil wrapped around the part of the surface pole.
- Rotor: The rotor is a cylindrical compone of iron or aluminum that is mounted on the motor shaft.
- End Rings: These are short-circuited rings configured at both ends of the rotor.
- Main winding: The main winding is the primary winding of the motor. It is attached to the power supply.
- Shading coil: The shading coil is a single-turn copper ring or bar that is 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 generated by the shading coil rotating slightly slower than the magnetic field of the main winding.
Working Principle of Shaded Pole Motor Definition
: The working of a Shaded Pole Motor is based on the principle of phase shift in the magnetic field.
- When AC voltage is provided by the main winding, a magnetic field is generated in the stator poles.
- The shading coil is configured in an asymmetrical fashion around a pole face. It results in part of the pole being more magnetically conductive than the rest.
- As the AC voltage varies, the shading coil induces eddy currents in the shaded part of the pole, which results small time lag in the magnetic field build-up.
- Due to this time lag, the magnetic field is not accurately configured with the pole, producing a rotating magnetic field.
- This rotating magnetic field interacts with the rotor and starts moving in the direction of the rotating field.
Shaded pole induction motor
A shaded pole induction motor is a type of single-phase induction motor that comes with a magnetic field generated by the main winding and shading coil. The shading coil is a single-turn ring or bar positioned around every pole of the stator. When current passes through the main winding it causes a field that rotates around the stator. Shading coil also has current passing through it but current is delayed by some amount.
The delay is caused by the magnetic field generated by the shading coil rotating slowly then the magnetic field generated by the main winding. The difference in the speed of the 2 magnetic fields produced a rotating torque that starts the motor.
Shaded pole motors are the simple and less costly type of single-phase induction motor. They are used in different applications, such as fans, small appliances, and toys.
Here are some of the main features of a shaded pole induction motor:
- It is a single-phase motor.
- It comes with a main winding and a shading coil.
- The shading coil is a single-turn copper ring or bar that is positioned around a portion of each pole of the stator.
- The shading coil produces a rotating magnetic field that is slightly slower than the magnetic field generated by the main winding.
- This difference in the speed of the 2 magnetic fields produces a rotating torque that starts the motor.
- Shaded pole motors are the simple and less expensive ingle-phase induction motors.
Shaded pole motor diagram
Here is a diagram of a shaded pole induction motor:
The stator of the motor comes with 2 poles, each of which has a main winding and a shading coil. The main winding is attached to the power supply, and the shading coil is configured with the main winding through a capacitor.
When current passes through the main winding, it causes a magnetic field that rotates around the stator. The shading coil also has current flow, but the current is delayed by a small amount. This delay results in the magnetic field generated by the shading coil rotating slower than the magnetic field of the main winding. The difference in the speed of the 2 magnetic fields produces a rotating torque that starts the motor.
The rotor of the motor is a squirrel cage rotor. The squirrel cage rotor is created with a series of copper bars that are short-circuited at each end. When the motor starts, the magnetic field from the stator induces currents in the rotor bars. These currents produce a magnetic field that interacts with the stator field, causing the rotor to rotate.
Why Is It Called a Shaded Pole Induction Motor?
A shaded pole induction motor is known as a shaded pole motor due to the shading coil that is placed around a portion of each pole of the stator. The shading coil is a single-turn copper ring or bar that is attached to the main winding through a capacitor.
The shading coil produces a rotating magnetic field that is slower than the rotating magnetic field generated by the main winding. This difference in the speed of the 2 magnetic fields makes a rotating torque that starts the motor.
The name “shaded pole” comes from the fact that the shading coil shades off the pole, which results in the magnetic field in that part being weaker. This weaker magnetic field rotates slightly slower than the stronger magnetic field in the unshaded part of the pole.
Shaded Pole Induction Motor of Characteristics
- Self-starting: Shaded pole induction motors are self-starting, which means that they do not need a starting capacitor or other device to start them. Since the shading coil creates a rotating magnetic field that is slower than the rotating magnetic field created by the main winding. This difference in the speed of the 2 magnetic fields makes a rotating torque that starts the motor.
- Simple and inexpensive: These are simple and inexpensive to manufacture. Since they have a relatively simple design and do not need any special components.
- Rugged and reliable: They are rugged and reliable. This is because they are made with simple and durable components.
- Low efficiency: They have low efficiency, especially at low speeds. As the shading coil causes some power loss.
- Low starting torque: Shaded pole induction motors have low starting torque. Since the shading coil only produces a small amount of rotating torque.
- Not suitable for high-performance applications: Shaded pole induction motors are not good for high-performance applications that need high starting torque or high efficiency.
Applications of Shaded Pole Induction Motor
- Fans: Shaded pole induction motors are commonly used in fans. They are employed in ceiling fans, table fans, and exhaust fans.
- Small appliances: These motors are also used in small appliances, like mixers, blenders, and food processors.
- Toys: it is also used in a variety of toys, like electric cars, remote-controlled toys, and windup toys.
- Clocks: Shaded pole induction motors are used in clocks and timers.
- Electronic devices: It is used in electronic devices, like CD players, DVD players, and printers.
- Portable tools: It is also used in portable tools, like drills, saws, and grinders.
- Air conditioners: Shaded pole induction motors are used in the fans of air conditioners.
- Refrigerators: These motors are used in the fans of refrigerators.
Why is the Shaded Pole Induction Motor suitable for low power rating?
Here are some of the causes why shaded pole induction motors are best for low power ratings:
- Simple design: Shaded pole induction motors come with a simple design that has a stator with a single winding and a rotor with a squirrel cage. This simple design makes them less costly to manufacture than other types of induction motors.
- Self-starting: These induction motors are self-starting, they do not need a starting capacitor or other device to start them. This makes them best for applications where a simple and less costly motor is needed.
- Low efficiency: They have low efficiency, especially at low speeds. Since the shading coil causes some power loss. However, this is not a main concern for applications where low power ratings are required.
- Low starting torque: They provdies low starting torque. This means that they are not good for applications where high starting torque is need. However, this is not a main concern for applications where low power ratings are needed
How does the Rotating Magnetic Field Produce in a Shaded Pole Induction Motor?
A rotating magnetic field is generated in a shaded pole induction motor by the main winding and the shading coil. The main winding is the primary winding of the motor. It is attached to the power supply. The shading coil is a single-turn copper ring or bar that is positioned around a portion of every pole of the stator. It is attached to the main winding through a capacitor.
When current passes through the main winding, it produces a magnetic field that rotates around the stator. The shading coil also has current flowing through it, but the current is delayed by a small amount. This delay resulted in the magnetic field produced by the shading coil rotating slightly slower than the magnetic field produced by the main winding. The difference in the speed of the magnetic fields creates a rotating torque that starts the motor.
The shading coil made the shaded pole induction motor self-starting. Without the shading coil, the motor would not be able to start on its own.
Here is more detail about how the rotating magnetic field is produced in a shaded pole induction motor:
- When current flows through the main winding, it produces a magnetic field that rotates around the stator. This magnetic field is known as the main field.
- The shading coil is configured around a portion of every pole of the stator. The shading coil is attached to the main winding through a capacitor.
- The capacitor resulted in the current in the shading coil being delayed by a small amount. This delay causes the magnetic field generated by the shading coil to rotate slightly slower than the magnetic field made by the main winding.
- The difference in the speed of the 2 magnetic fields produces a rotating torque that starts the motor.
The rotating magnetic field causes the rotor of the motor to rotate. The rotor is created with a series of copper bars that are short-circuited at each end. When the motor starts, the magnetic field from the stator induces currents in the rotor bars. These currents produce a magnetic field that interacts with the stator field, resulting the rotor rotation.
Advantages of Shaded Pole Induction Motor
- Self-starting: Shaded pole induction motors are self-starting, not require a starting capacitor or other device to start them. This makes them best for applications where a simple and inexpensive motor is needed.
- Simple design: These motors have a simple design that comes with a stator with a single winding and a rotor with a squirrel cage. This design makes them less costly to manufacture than other induction motors.
- Low cost: Shaded pole induction motors are the least costly type of single-phase induction motor. This makes them the best option for applications where cost is a major factor.
- Rugged and reliable: These motors are rugged and reliable. They are created with simple and durable components that can handle the harsh conditions of many applications.
- Low maintenance: Shaded pole induction motors need very little maintenance. That makes them a best option for applications where maintenance is difficult or costly
Disadvantages of Shaded Pole Induction Motor
- Low starting torque: These motors have low starting torque. This means that they are not best for applications where high starting torque is needed. For instance, shaded pole induction motors are not used for applications like electric drills or saws.
- Low efficiency: They have low efficiency, especially at low speeds. This is due to the shading coil causing some power loss. The efficiency of a shaded pole induction motor is about 50%.
- Not suitable for high-performance applications: it is not best for high-performance applications that need high starting torque or high efficiency. For instance, shaded pole induction motors are not used for applications like electric vehicles or industrial machinery.
- Difficult to reverse: It is difficult to reverse the direction of rotation of a shaded pole induction motor. Since the shading coil creates a rotating magnetic field that is always in the same direction.
- Not suitable for applications with variable speed: They is not good for applications with variable speed. This is because the speed of a shaded pole induction motor is directly proportional to the frequency of the power supply.
Synchronous motors vs Shaded Pole Motor
| Feature | Synchronous Motor | Shaded Pole Motor |
|---|---|---|
| Speed | Synchronized with the rotating magnetic field of the stator winding | Not synchronized with the rotating magnetic field of the stator winding |
| Power factor | High | Low |
| Starting torque | High | Low |
| Efficiency | High | Low |
| Cost | High | Low |
| Applications | Clocks, electric generators timing devices, , traction motors | Fans, machine tools blowers, pumps, |
Faqs
- What is a shaded pole motor?
A shaded pole motor is a single-phase induction motor that comes with copper ring or bar surrounding each pole. This produces rotating magnetic field that resutls the motor to start and run.
- What are the advantages of shaded pole motors?
The benifits of shaded pole motors include: * They are simple and less coslty to manufacture. * They are self-starting, so they do not need a start capacitor or other starting device. * They are rugged and reliable. * They are used in a different applications,like fans, pumps, and small appliances.
- What is a capacitor and shaded pole?
A capacitor is a device that stores electrical energy. A shaded pole motor uses a capacitor to start the motor. The capacitor is connected in parallel combination with the shaded pole winding. When the motor is turned on, the capacitor charged and then discharges, making strong magnetic field that helps to start the motor.
- Which of the following are the features of a shaded pole motor?
The features of a shaded pole motor include:
* It has a single-phase stator winding.
* It comes squirrel cage rotor.
* It has shaded pole winding on each pole.
* It is self-starting.
* It has low efficiency.
- What is the principle of shaded pole?
The principle of shaded pole is that a copper ring or bar surrounding a part of a pole creates a magnetic field that is delayed in time than the magnetic field of the unshaded portion of the pole. This prodcues a rotating magnetic field that causes the motor to start and run.
- What is the efficiency of a shaded pole motor?
The efficiency of a shaded pole motor is about 30%. This is due to the the shaded pole winding cprodcues a lot of drag on the motor, which reduces efficiency.
- What is the disadvantage of shaded pole motor?
The disadvantages of shaded pole motors include:
* low efficiency. * They are not very powerful.
They can be noisy.
They are not reversible.
- Does shaded pole motor have only one winding?
Yes, a shaded pole motor has only one winding. it is the main winding that is responsible for prodcuing the magnetic field. The shaded pole winding is a secondary winding that is connected in parallel with the main winding.
- What is the direction of a shaded pole motor?
The direction of a shaded pole motor is defined by the direction of the current flow in the main winding. If the current flows in one direction, the motor will rotate in one direction. If the current passes in the opposite direction, the motor will rotate in the opposite direction.
- How many windings does a shaded pole motor have?
A shaded pole motor has 2 windings: the main winding and the shaded pole winding. The main winding is used for creating the magnetic field, and the shaded pole winding for creating a rotating magnetic field that helps to start the motor.
- Why is the efficiency of a shaded pole motor low?
The efficiency of a shaded pole motor is less because the shaded pole winding makes a lot of drag on the motor. This drag dereases the amount of power that is available to turn the motor.
- Will a shaded pole motor rotate?
Yes, a shaded pole motor will rotate. However, it will only rotate in one direction. The direction of rotation can be changed by reversing the current flow in the main winding.
- Are shaded pole motors synchronous?
No, shaded pole motors are not synchronous motors. Synchronous motors rotate at a constant speed that is synchronized with the frequency of the power supply. Shaded pole motors do not rotate at a constant speed. The speed of a shaded pole motor based on the load that is connected to it.
- What is the function of shaded pole induction motor?
The function of a shaded pole induction motor is to tansform electrical energy into mechanical energy. The motor does this by rotating a shaft that is attaching to a load. The rotating shaft turns the load,like fan blade or a pump impeller.
- Why do motors have to reverse pole direction?
Motors have to reverse pole direction in order to vary the direction of rotation of the shaft. This is required for some applications,like fans and pumps.
