8._Single_Phase_Motors

8._Single_Phase_Motors - EEL 3211 ( 2011, H. Zmuda) 8....

Info iconThis preview shows pages 1–11. Sign up to view the full content.

View Full Document Right Arrow Icon

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
This is the end of the preview. Sign up to access the rest of the document.

Unformatted text preview: EEL 3211 ( 2011, H. Zmuda) 8. Single-Phase Motors 1 Miscellaneous Topics July 6, 2011 EEL 3211 ( 2011, H. Zmuda) 8. Single-Phase Motors 2 Single-Phase Motors EEL 3211 ( 2011, H. Zmuda) 8. Single-Phase Motors 3 Single-Phase Motors: Most familiar of all motors. Used in home appliances and portable machine tools. Used when three-phase power is not available. There are many varieties of single-phase motors. We will limit our attention to a few popular ones. EEL 3211 ( 2011, H. Zmuda) 8. Single-Phase Motors 4 Single-Phase Motors: Single-Phase motors are very similar to three-phase induction motors. They have a squirrel cage rotor that is identical to that of the induction motor studied. The stator has a main winding that creates a set of N and S poles. It also has an auxiliary winding that only operates for a short time during start-up. The auxiliary winding has the same number of poles as the main EEL 3211 ( 2011, H. Zmuda) 8. Single-Phase Motors 4 Single-Phase Motors: Single-Phase motors are very similar to three-phase induction motors. They have a squirrel cage rotor that is identical to that of the induction motor studied. The stator has a main winding that creates a set of N and S poles. It also has an auxiliary winding that only operates for a short time during start-up. The auxiliary winding has the same number of poles as the main winding. EEL 3211 ( 2011, H. Zmuda) 8. Single-Phase Motors 5 S S I S I 120 V, 60 Hz ac source Rotor Rotor and main winding of a two-pole, single-phase motor. Stator The flux pulsates but does not rotate . No revolving field is produced EEL 3211 ( 2011, H. Zmuda) 8. Single-Phase Motors 6 S I S I F F 120 V, 60 Hz ac source Rotor Current Currents in the rotor bars when the rotor is stationary . The resulting forces cancel each other and no torque is produced . S EEL 3211 ( 2011, H. Zmuda) 8. Single-Phase Motors 7 Single-Phase Motors: Initially the rotor behaves like the short-circuited secondary of a transformer and the motor has no tendency to start by itself. If we were to spin the rotor in one direction or the other it would continue to rotate in the direction of spin. The rotor would quickly accelerate until it reached a speed slightly below synchronous speed. The starting torque is zero, the torque could be quite powerful at synchronous speed. Let us examine the operation is greater detail. EEL 3211 ( 2011, H. Zmuda) 8. Single-Phase Motors 8 Typical torque-speed curve of a single-phase motor. EEL 3211 ( 2011, H. Zmuda) 8. Single-Phase Motors 9 S I S I ac source Principle of Operation Cross-Field Theory . S Rotation As soon as the rotor begins to turn an emf is induced in the rotor bars that cut the stator flux S . This voltage increases as the speed increases. EEL 3211 ( 2011, H. Zmuda) 8. Single-Phase Motors 10 S I S I ac source Principle of Operation Spin the rotor counterclockwise ....
View Full Document

Page1 / 48

8._Single_Phase_Motors - EEL 3211 ( 2011, H. Zmuda) 8....

This preview shows document pages 1 - 11. Sign up to view the full document.

View Full Document Right Arrow Icon
Ask a homework question - tutors are online