Max possible start torque with an overvoltage or?

[Barry1961]

I have an application where a gearmotor needs to run for one second three times a day. During this brief period it needs to produce a minimum of 18 in-lb. I want the motor to be as small as possible for low rotor inertia, light weight, low cost and it needs to be TENV. I would like to do this with an 1/8hp motor since they come std. TENV.

What can I do to get 18 in-lb out of an 1/8hp motor for a very short period of time. The voltage on site 1 phase 115VAC. The actual duty cycle will be approx. .25 sec FWD, brake for .25 sec., .25 sec REV, brake for .25 sec. They should be at least 1 hour between each cycle. I am hoping the brake will be mechanical.

Some of the things I am thinking about would be running the motor with a higher than rated voltage (step up xfmr),oversized capacitors, alternative motor wiring or even alternative windings.

Thanks in advance, Barry1961

 

[electricpete]

That is way out of my area. Torque should increase by voltage squared as you know.

1 second is pretty darned short. Depending on what you are trying to accomplish maybe a NEMA design D torque speed characteristic would help?



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[aolalde]

A (4) four poles single- phase 1/8 HP motor built under NEMA MG1 standard, has locked rotor torque of 24 ounce-feet at 115 volts ( 32 0z-feet for 6 poles).

You need 18 Lb-in = 1.5 Lb-ft =24 oz-feet

The torque increases with a ratio of voltage proportion squared until magnetic saturation is reached.

Hopefully you are right on the money with 1/8 HP 4 Poles, so no need for overvoltage.

You could buy TEFC motor and remove the fan.

 

[jraef]

At that size, short duty cycle etc., have you considered doing this with a stepper or servo?

Quando Omni Flunkus Moritati

 

[jbartos]

Suggestion: Visit

http://www.thomasregister.com

and type Motors: Electric under Product or Service, which will return 508 companies to approach to. It may be a good idea to coordinate your effort with the motor sales representative to obtain the motor parameters, cost, etc. since they have all information that you need at their fingertips.

 

[Barry1961]

Thanks for the input. I found some hard start "kits" that they use for HVAC units. They say they can boost the starting torque by up to 590% on a PCS motor. I am going to try one of these since they are cheap and off the shelf.

Barry1961

 

[aolalde]

Barry1961

Thanks for the feedback, let us know how your selection worked.