Electric Motors/Generators

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In summary, the conversation discusses the possibility of an AC motor also functioning as an AC generator, and whether the speed of a motor is dependent on voltage and torque or vice versa. It is mentioned that while DC motors can easily function as generators, AC motors may require certain modifications to do so. The answer to whether motor speed is proportional to voltage or current is not straightforward due to the variety of motor designs.
  • #1
unique_pavadrin
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we have recently started to learn about motors and generators. A DC motor can be a DC generator and vice versa, but is this the case with AC (an Ac motor being an AC generator)? Why or why not?

Also is the speed of the motor dependent upon the voltage and the torque of a motor due to the current supplied to the motor? or is it the opposite? If so why is this the case?

Many thanks to all whom chose to reply,
unique_pavadrin
 
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  • #2
Yes, an AC motor is definitely possible. There are tricks that you can do with AC power, such as rectifying (that is to say slice up) the wave with a diode, mutual inductance (the idea of transformers), and many other things that open up many possibilities.

Are you asking whether the DC motor speed is proportional to current or voltage? Most likely the answer is yes, but there are so many types of motors out there that I don't want to discount anything.
 
  • #3
unique_pavadrin said:
we have recently started to learn about motors and generators. A DC motor can be a DC generator and vice versa, but is this the case with AC (an Ac motor being an AC generator)? Why or why not?

Also is the speed of the motor dependent upon the voltage and the torque of a motor due to the current supplied to the motor? or is it the opposite? If so why is this the case?

Many thanks to all whom chose to reply,
unique_pavadrin

On a practical level the typical AC motor won't act as a generator. Without some current already flowing through it there is no magnetic field to start the ball rolling as far as generating electricity from a varying magnetic field. DC motors, especially the small kind have permanent magnets.

Now if you have an AC induction motor running and you somehow kicked it into reverse by applying enough torque it will cause a backlash current. But it won't (I don't think) sustain itself as an AC generator. You'll have to design the whole thing differently.

There are AC motor designs which do use permanent magnets and which do like their DC counterparts work both ways as motor and generator. They however aren't as efficient and cost more to build so you won't find them in your typical commercial application.

But in the most general terms your question can't be answered simply as there is a broad range of motor designs with varying ability to work in reverse as generators. (Including the DC ones).
 
  • #4
thank you very much for both replies, they have both been of great help, only wish i had a physics teacher as good as
 

1. How do electric motors work?

Electric motors work by converting electrical energy into mechanical energy. This is achieved through the interaction of magnetic fields. When an electric current flows through a wire that is placed in a magnetic field, it creates a force on the wire, causing it to move. This movement of the wire is what creates the mechanical energy that powers the motor.

2. What is the difference between an electric motor and a generator?

The main difference between an electric motor and a generator is the direction of energy flow. An electric motor converts electrical energy into mechanical energy, while a generator converts mechanical energy into electrical energy. In other words, a motor produces motion, while a generator produces electricity.

3. What factors affect the efficiency of electric motors?

The efficiency of an electric motor is affected by several factors, including the design of the motor, the quality of its components, the type of power source, and the load that the motor is operating under. Generally, smaller motors tend to be more efficient than larger ones, and direct current (DC) motors are more efficient than alternating current (AC) motors.

4. Can electric motors and generators be used interchangeably?

In some cases, electric motors and generators can be used interchangeably, but it depends on the specific application. Motors can be used as generators, and vice versa, by simply reversing the flow of energy. However, the design and components of each device are optimized for their respective functions, so they may not be as efficient when used interchangeably.

5. What are some common uses for electric motors and generators?

Electric motors and generators have a wide range of uses in various industries and applications. Some common uses for electric motors include powering appliances, electric vehicles, industrial machinery, and household tools. Generators are commonly used for backup power, in renewable energy systems, and in large-scale power plants to produce electricity for homes and businesses.

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