Alternating poles in the stator of an alternator

In summary, the person has been working with an alternator and purchased a magnetic pole detector to identify poles. However, the detector did not detect any poles when placed on the stator. They also tried the detector on direct current coils and got results. They then ran tests on an alternator stator and got the same results, with the detector not identifying any poles. The person is wondering why the detector is not identifying poles in the stator's iron core, regardless of whether it is direct current or alternating current. Possible explanations include the magnetic flux density not being high enough and the alternator generating an alternating current rather than a steady state field.
  • #1
jearls74
53
1
I have run into something i don't understand while working with an alternator. I purchased a magnetic pole detector to identify the poles of some magnets and tried to see if i could detect the changing magnetic field of the alternator in my car while it was running by placing the pole detector on a specific point at the stator, but the pole detector didnt do anything, didnt indicate a changing field. So i tried the pole detector on a couple of direct current coils i built some time ago and the pole detector identified the poles of the coils. I bought a alternator stator to run tests on and i ran direct current through one phase of the 3 phases of the stator and got the same results as when the alternator in my car was running producing an alternating current, the pole detector didnt identify any poles, i also connected the stator to household wall current through a variable AC transformer at low voltage but with a high current flowing through the winding of the one phase of the stator and got the same results, no pole detection. Why does the detector not identify poles in the stators iron core? direct current or alternating current, the results are the same, the pole detector doesn't identify either pole. Can anyone offer some explanation why?
 
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  • #2
Your magnetic flux density is probably not high enough. Permeability of free space is quite low compared to that of a iron core.

A motor/generator don't need that high magnetic flux density since the airgap between rotor and stator is so small.
Your car alternator is also more likely a 3 phase synchrounos generator, which generates a rotating magnetic field. The rotor (poles) changes direction as the shaft turns, so you don't have any stationary magnetic poles.
 
  • #3
I'm pretty sure that the magnetic pole detector is used to identify poles of a steady state field. The alternator does not have a steady state field in it. It generates AC voltage then rectifies it. If the detector is sensitive enough you should be able to hold it up to a single wire carrying current and it should detect the field around the wire if the current is strong enough and you hold the detector in the correct orientation. If you do this near a pos and neg wires the fields will tend to cancel each other out. L
 

1. What are alternating poles in the stator of an alternator?

Alternating poles in the stator of an alternator refer to the arrangement of the magnetic poles in the stationary part of the alternator. These poles alternate between north and south poles and are responsible for generating the alternating current (AC) in the alternator.

2. How do alternating poles work in an alternator?

The alternating poles in the stator of an alternator work by interacting with the rotating magnetic field of the rotor. As the rotor spins, the magnetic field from the poles in the stator changes direction, causing the coils in the stator to produce an alternating current.

3. What is the purpose of alternating poles in an alternator?

The purpose of alternating poles in an alternator is to generate an alternating current, which is essential for powering most electrical devices. This alternating current can be easily converted to direct current (DC) using a rectifier, making it suitable for use in various applications.

4. Can the number of alternating poles in an alternator be changed?

Yes, the number of alternating poles in an alternator can be changed to alter the frequency of the generated alternating current. By changing the number of poles, the speed at which the rotor spins can also be adjusted, thus changing the frequency of the alternating current produced.

5. What are the advantages of having alternating poles in an alternator?

Having alternating poles in an alternator allows for the production of alternating current, which is the standard form of electricity used in most power grids. It is also more efficient and easier to convert to different voltages, making it suitable for a wide range of applications.

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