I have a question that maybe someone here can help me with.
I am making a converter and for some reason it does not work on a motor I have.
I hook L1 and L2 to the motor wires. I hook my capacitor bank to L2 and the third leg of the motor.
I put power to it and hit the momentary button to fire the capacitors.
The 5hp motor Fires up and away it goes. Everything is great.
I also used it in the same way to start another 5hp motor, no problems.
Now, I step up to a 7.5 HP motor and it will not start it. My first thought was that I need more juice from the start capacitors but I am already running plenty by my calculations.
The start capacitors are 216-259 MF each and I have four of them. Using the low end of 216, I have 864 Mf total and that divided by 7.5HP would be 115 MF per HP. That should be plenty to start this motor. It does make a difference but still does not get the motor up to speed to continue running.
I though maybe the motor was bad so I took it to work and hooked it to the converter at work and it fired right off, no problem.
I took the cover off the work converter to see what capacitors were in there. There are four of them and they are mounted in a manner that does not allow you to see the writing on them. They are in there with silicone holding them in place. I don't want to yank them out because the run capacitors have had the information sanded off so the start capacitors probably do as well.
Anyone have any suggestions as to what the problem could be?
I need 7.5HP to run my 5HP air compressor.