AC motor and power inverter, can it work?, 1hp ac motor, 12v to 120ac 2000w inve

[raycenteno]

Hopefully some of you can bring some insight on what i could do to this project i wish to work on. I am trying to power up an ac motor with an inverter, but it just does not seem to work.
Here are the specs: the motor- 1hp 115vac 60 hz 11a. the inverter-12vdc to 120vac 2kwatts max 4k, mod sinewave.
I definately must be missing something somewhere, the inverter powers up to about 1300 watts on its led meter, the motor tries to turn but within about 3 secs the inverter alarm goes off and shuts off.
I did try manually to turn it and then flip the switcch, but i get the same result.
So far i have tried 4 differ motors.
(1) the one i mentioned, it is treadmill motor
(2) a frigidaire dryer motor rated at 1/3 hp
(3) a dayton motor rated 1/2 hp, this one only had 2 connectors for it
(4) an old leeson, a 1hp motor that has a hump on it, it's capacitor, this motor actually started and was prob about 80 rpm when the inverter shut off.
I was thinking about transformers, maybe if I am able to find one that has a 1 to 1 ratio, but i am not sure if this would be my answer.
I also thought maybe the inverter is not producing the right hz, but i am not sure how to fix this and i do not have the equipment to check the hz.
Can anyone help?

 

[audioguru2]

Hi Ray,
I think any motor draws a high inductive current when it starts that the meter can't read very well. The inductive part overheats the transistors in the inverter.
The inverter just ain't powerful enough!

You could add Power Factor Correction to the motor with a changing capacitor but it would be a can of worms.

 

[raycenteno]

thank you audioguru,
i was trying to use the ac motor instead of a dc motor, because the ac motor is 1/3 the size and about 1/4 the weight. which benefits my project greatly.
what is a power factor correction, and how difficult is this to achieve since you mentioned that it is a can of worms?

 

[audioguru2]

Hi Ray,
Look at Power Factor Correction on Google. Basically a capacitor is added across the mains at the correct time and its value must match the motor's load. It would need different ones switched-in if the motor's load (treadmill's heavy weight user) or speed (treadmill) is changed. ;D

 

[Alun]

Be warned about using power factor correction capacitors with inverters, if it decedes to form a resonant circuit with the secondary at 60Hz or harmonic then a huge voltage will build up causing a large current to flow that could even cause it to explode, as a precaution never connect the capacitor to the inverter without the motor.

 

[raycenteno]

well guys, i did try the capacitor approach, but i was unsuccesfull. back to the drawingboard...

 

[2old4digital]

You need to check the power rating on the inverter most of them will say 2000 but that will be surge max and the actual power rateing is only 1000 and will not run your motor, try the formula  E X I=P to find out the wattage you will need to run your motor, then add 50% for start up wattageany you can find a motor that will work with your inverter.  E = voltage and I = amps. If you do get it to work with the mods that you have been informed of the motor will prb not work as eff. as designed but anything is possible

 

[MP1]

Measure the start up load of the motor while attached to a mains powered circuit. You probably just need a larger inverter.

I have seen equipment that draws 2 to 3 amps continuous, but which needs 10 amps available due to start up.

MP

 

[Alun]

A soft start might be a good idea.

 

[2old4digital]

  Forgot to tell you. Divide  P by E and you will get the max amps at the output volts your inverter will work at. P=Watts    E= Volts. That way you can find the motor that will work and do so at max hp and effic. Remember that most inverters are modifide sinwave and do not actu. put out 110 vac all the time but that voltage will be close eno for the math for your requirments