How Can I Determine the Number of Poles in a Burnt AC Induction Motor?

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SUMMARY

Determining the number of poles in a burnt AC induction motor can be achieved by inspecting the coils and understanding their connections. While formulas exist that relate frequency and RPM to pole count, the absence of a nameplate complicates this process. A key insight is that a 4-pole motor does not necessarily have four coils in each phase; the configuration of the coils is critical. Therefore, analyzing the stator coil connections is essential for accurate pole determination.

PREREQUISITES
  • Understanding of AC induction motor principles
  • Familiarity with motor winding configurations
  • Knowledge of electrical frequency and RPM relationships
  • Experience with motor repair and rewinding techniques
NEXT STEPS
  • Research the formulas for calculating the number of poles based on frequency and RPM
  • Learn about different winding configurations in AC induction motors
  • Study the process of inspecting and rewinding burnt motor coils
  • Explore resources on troubleshooting and repairing AC induction motors
USEFUL FOR

Motor repair technicians, electrical engineers, and anyone involved in the maintenance or rebuilding of AC induction motors will benefit from this discussion.

BlackMelon
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Hello,

I want to know determining the number of poles by inspecting coils inside the motor. Generally, there are formulas allowing us to plug a frequency, an rpm, and give off the number of poles, or we can just simply look at its nameplate.

My reason for needing the inspecting is that my brother fixes burnt AC induction motors. As it was burnt by overloading or whatsoever already, he can not find the number of poles by operating it. Luckily, there are nameplates.

One vulnerable point is in the case that a customer brings his/her burnt motor with a burnt nameplate.(The windings are burnt, but it still can be observed its winding physical details like in the attached file) In this case,"How could I determine the number of poles by tracking stator coil connections?"

I try to google this many times but what I've found are using the formulas mentioned above and looking at the nameplate. Also, what I've found is that a 4 poles induction motor does not always have 4 coils in one phase but it has to take care of how coils are connected ,and the site does not tell any further.

the site:
http://www.reddit.com/r/AskEngineers/comments/1xgsee/how_many_poles_are_there_in_a_threephase_motor/
Thank you
 

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To a degree, re-winding a burnt up motor is a bit like building a new motor. You need to ask what speed is required for the re-built motor along with line frequency. Then figure the required number of poles from there.
 
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Likes   Reactions: Jeff Rosenbury
Suppose that I've got a required frequency and speed giving number of poles by using formulas. For examples, I've got 4 poles in one phase. Will there be only 4 coils in one phase producing 4 poles? (What I've learned from another site is that we have to take those coils' connection into account, but it didn't tell anything further, so I am not confident to trust it)
 
Last edited:

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