Understanding Alternating Currents Motors - Issues & Solutions

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Discussion Overview

The discussion centers around understanding alternating current (AC) motors, particularly focusing on their operation, types, and specific components. Participants explore various aspects of AC motors, including magnetic principles, types of induction motors, and starting mechanisms.

Discussion Character

  • Exploratory
  • Technical explanation
  • Conceptual clarification
  • Debate/contested

Main Points Raised

  • A new participant expresses confusion about the workings of AC motors and asks several foundational questions regarding inducing current, magnetic flux, and the benefits of cutting magnetic flux.
  • One participant suggests a Wikipedia link as a resource for understanding AC motors.
  • Another participant critiques the Wikipedia entry for omitting the repulsion-start induction motor, describing its unique features and advantages over capacitor-start induction motors.
  • A participant shares personal experience with modern single-phase AC motors that utilize a centrifugal mechanism for starting, prompting a question about whether the original poster's motor employs a similar mechanism.
  • Further clarification is provided about the types of single-phase AC induction motors, including split-phase, capacitor-start, and repulsion-start motors, along with their methods for reversing direction.

Areas of Agreement / Disagreement

Participants present multiple viewpoints regarding the types and mechanisms of AC motors, with no consensus reached on the best resources or explanations for the original poster's questions.

Contextual Notes

The discussion includes various assumptions about the knowledge level of participants and the definitions of technical terms, which may not be universally understood.

Who May Find This Useful

Individuals interested in the fundamentals of AC motors, including students, hobbyists, and those seeking to understand motor operation and types.

Justinyeoh
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Hi,I am new here^^17 years old...

I got a little problem with understanding how simple alternating currents motors/AC Motors work...

Anyone has a good Table or Figure??

Magnetic problems:
1)Whats the difference between inducing current and normal electric current??
2)Whats the meaning of "Cutting the Magnetic Flux"
3)Whats the good thing of cutting magnetic flux

Sorry for asking so many questions at once...

Please help me.
 
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pallidin said:
Perhaps this will be of interest to you:

http://en.wikipedia.org/wiki/AC_motor
The Wikipedia website overlooks an important class of single-phase induction motors sold from about ~1905 to after WW I; the repulsion-start induction motor, which had a special set of rotor conductors (in addition to the squirrel cage) attached to a commutator, which the brushes lifted off of when the rotor neared the running RPM. See attached photo of one in my garage (Century Motor, U. S. Pat. Off. date 1915) with a radial commutator. One nice feature is that the starting surge current is lower, and the starting torque is higher, than an equivalent HP capacitor-start induction motor.

Bob S
 

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Bob S said:
The Wikipedia website overlooks an important class of single-phase induction motors sold from about ~1905 to after WW I; the repulsion-start induction motor, which had a special set of rotor conductors (in addition to the squirrel cage) attached to a commutator, which the brushes lifted off of when the rotor neared the running RPM. See attached photo of one in my garage (Century Motor, U. S. Pat. Off. date 1915) with a radial commutator. One nice feature is that the starting surge current is lower, and the starting torque is higher, than an equivalent HP capacitor-start induction motor.

Bob S

I have worked on similar "modern" single phase AC motors. One used a spring loaded "centrifugal" mechanism, to open a switch to the "starter winding" once the motor was at speed. (More current/torque for start-up).

Is your motor doing the same thing for the same purpose?
 
There are three types of single-phase ac induction motors with centrifugal starting switches; split-phase, capacitor-start, and repulsion-start. Both split phase and capacitor start are reversed by changing the wiring polarity of the starting coil. The repulsion-start motor is reversed by means of a lever to rotate the brush location. See the lever in my attachment photo above, to the left of the motor axle.

Bob S
 

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