Split phase motor.pptx

Split phase motor.pptx

1. Electrical Machines II Presentation: Split Phase Motor Group Members: Kamran Ali (ADP-002) Ameer Hamza (BS-004) Abdul Bilal (BS-006) Furqan Habib (BS-007)

2. Split Phase Motors: A split-phase induction motor is a type of single-phase induction motor in which the stator is provided with a starting or auxiliary winding (S) and a main or running winding (M ). The starting winding is displaced by 90° from the main winding as shown in the figure .

3. Why Single Phase Induction Motor is not Self Starting? A split-phase induction motor are not self-starting because the produced stator flux is alternating in nature and at the starting, the two components of this flux cancel each other, and hence there is no net torque.

4. Working Principle In split-phase motor two windings named main winding and starting winding. At the time of starting, both the main and starting windings should be connected across the supply to produce the rotating magnetic field, and when the supply is given to the stator the rotating magnetic field is produced. As the rotor bars are short-circuited, a current flows through them producing a magnetic field. This magnetic field opposes the revolving magnetic field and will combine with the main field to produce a revolving field.

5. Once the rotor starts rotating and attains a speed up to 75 to 80 percent of the synchronous speed, the starting winding can be disconnected from the supply by the centrifugal switch.

6. Construction The split-phase induction motor basically consists of a stator, a rotor, a centrifugal switch located inside the motor, two end shields housing the bearings that support the rotor shaft. In addition to the main winding or running winding, the stator of the split-phase induction motor carries another winding called auxiliary winding or starting winding. A centrifugal switch is connected in series with auxiliary winding. The purpose of this switch is to disconnect the auxiliary winding from the main circuit.

7. A split-phase motor has no capacitance in the auxiliary circuit. A phase shift to the main current is achieved by using narrow conductors to achieve high resistance to reactance ratio. Increasing the resistance means that the auxiliary winding can only be used during starting, otherwise, it would overheat. A split-phase motor has significantly lower torque at starting due to the reduced phase angle between main and auxiliary winding currents.

8. Components of 1-phase Induction motor: Stator Frame Stator Winding Rotor Rotor Winding Cooling Fan Bearings

9. Frame: Frame provides Mechanical support to the stator and rotor. It made from casting material. Stator: It is stationary part of induction motor. It consist stator winding. It is housed on the motor frame. Stator Winding: Star winding and Delta winding

10. Rotor: It is rotating part of machine. It housed on the shaft of the induction motor. It has two ends one is driving end and the other one is non-driving end. Mechanical load is connecting with driving end while cooling fan is connected on non-driving end. Both the end is connected with bearing for free rotation means of reduced friction losses . Rotor Winding: Squirrel cage induction motor Slip ring induction motor

11. Characteristics The characteristics of split-phase induction motors are given as follows − The split-phase motor has the starting current about 7 to 8 times of the full load current. The starting torque of a split-phase induction motor is about 1.5 times of the full-load torque. The maximum or pull out torque is about 2.5 times of the full-load torque at about 75% of synchronous speed. Split-phase induction motors are less expensive, thus, they are very popular motors in the market.

12. Applications To drive fans In washing machines Oil burners Smalls machine tools Blowers and centrifugal pumps Food mixers and grinders

13. Advantages The advantages of a split-phase induction motor include the following. The motor is economical and installed in many domestic appliances. It can be changed once it wears out before trying to reverse it. These are available in different frame sizes so that they can be placed effortlessly in most of the machines.

14. Disadvantages The disadvantages of a split-phase induction motor include the following . These motors have less starting torque, so not suitable for above 1 KW. The disadvantage of this motor is power output and efficiency. As compared to a 3-phase motor, these are unsuccessful while changing the energy from electrical to working. These motors rely simply on the different resistance & inductance of the starting winding. These motors are used where high starting torque is mandatory like an air compressor

15. Conclusion A split-phase induction motor is a type of single-phase induction motor in which the stator is provided with a starting or auxiliary winding (S) and a main or running winding (M). The starting winding is displaced by 90° from the main winding. It is not self-start. Split-phase induction motors are less expensive. These are available in different frame sizes .