What is the initial force required to start an electric motor and generator?

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Discussion Overview

The discussion revolves around determining the initial force required to start an electric motor and generator system. Participants explore the relationship between force, torque, and the mechanics of starting an electric motor, including assumptions about power sources and configurations.

Discussion Character

  • Exploratory
  • Technical explanation
  • Mathematical reasoning
  • Debate/contested

Main Points Raised

  • One participant seeks to understand the initial force needed for an electric motor to start turning, emphasizing the need for a force measurement in Newtons rather than torque or energy.
  • Another participant suggests finding the torque of the motor to relate it to force, given the rotor dimensions.
  • A participant expresses confusion about the feasibility of running an electric motor on gas, indicating a need for clarification on power sources.
  • A participant proposes a calculation involving horsepower (HP) to determine the force needed to start moving an electric car, referencing a formula that relates HP to force and RPM.
  • There is a question about assuming the RPM at start and whether it can be set to 1 RPM for calculation purposes.
  • A participant questions the relationship between the motor's force and the torque on the generator, seeking clarity on how these values interact based on the shaft distance.

Areas of Agreement / Disagreement

Participants express various viewpoints and calculations regarding the initial force and torque relationships, but no consensus is reached on the specific values or methods to determine the initial force required.

Contextual Notes

Participants make several assumptions regarding power sources, dimensions, and initial conditions, which may affect the calculations and conclusions drawn. The discussion includes unresolved mathematical steps and dependencies on specific configurations.

Who May Find This Useful

Individuals interested in electric motor mechanics, engineering students, and those exploring the principles of force and torque in electrical systems may find this discussion relevant.

wassim99
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Hello all,
So I am confused about a a scenario and I hope you guys can hook me up with some explanation.
So I am trying to find the initial force needed for an electric motor to turn. I am not looking for torque or energy just the Newtons just to start from scratch and keep going with the math. with a force X during a certain time with a length Y of the shaft, etc.. I think this is the best way to understand how does the electric motor work. so if I have a the motor connected to a wall plug or running on gas or battery how much force will it take that after we convert it to torqu it will be enough to turn the electric motor shaft.
now let's assume the motor shaft hooks to a small generator through a belt. How much force will the generator need to turn.
I believe the force of the motor should be the sum of both forces or something within those lines. Can you guys tell me how to get the initial force on each, just the force to get it to start turning. I am attaching a little drawing to show the setup.
please use any initial assumptions you want as long as it serves the purpose of finding the initial force.
Thanks a lot for your time and help
 

Attachments

  • motor+generator.png
    motor+generator.png
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Engineering news on Phys.org
Do you know how to find the torque of the motor? From there you can relate the force given you have the dimensions of the rotor.
 
wassim99 said:
...so if I have a the motor connected to a wall plug or running on gas or battery ...

I'm still trying to figure out how to run an electric motor on gas. Hmmm...
 
thanks all, that was fast.. :)
so Assuming that I need 10HP to start moving an electric car. HP=CxFxRPM/33000. usually it is 2TT (TxRPM)/33000 but torque is FxR and 2TT xR is C (circumference).
So F=CxRPM/330,00 x 10 =CxRPM/330,000. But How would I find the RPM at start, can I assume it is 1 RPM (just to get the car moving)
And the major question is: if the motor uses a 100N force that gives a 200Nm Torque (just for example). Will the torque on the generator attached to the shaft (in the picture above) be the motor force x the shaft or axle distance to where the generator connects to the motor?
THanks
 

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