Hi,
Can anyone help me please?

I have a GE 4Kw 5 Hp induction motor. It has been wired to run of three phase but I would like to run it on single phase. I have carried out research on the Internet but I am not confident with the information I have found.

I understand how to reconfigure the wiring of the three windings and I understand how start and run capacitors work. But other than using trial and error any information I have found has indicated that the start capacitor value should be anything from 120uf to 550uf and the run capacitor value should be between 10uf and 80uf. I would like to at least fairly accurate with values before trying out capacitors.

Has anyone got experience with a similar project or can point me in the right direction to working out the values of the capacitors.

I want to use this motor on a compressor and am confident that I can design the rest of the circuit to switch out the start capacitor and integrate the pressure sensing switch from the reserve tank but I would really appreciate any help you can give me with this.

Regards

Jim

 

Yes I am familiar and then some.

All you need to know and more.

http://www.electro-tech-online.com/threads/3-phase-converter-schematic-miller-system.100563/

 

Yes I am familiar and then some.

All you need to know and more.

http://www.electro-tech-online.com/threads/3-phase-converter-schematic-miller-system.100563/

Hi,

First thank you for your prompt reply. The link above certainly takes me to the best information I have come across by far.

I have 2 questions if you don't mind
1. I see that you have left the motor windings wired in star format. Is that always the case or do I change it to delta format?
2. My motor is 5hp therefore running the motor from a 240v ac supply would suggest that the value for C1/C2 would be 50uf, (using 10uf per hp). Is that 50uf for each capacitor?

I know these questions may seem trivial but I really want to get this right and again you have been most helpful.

Regards

Jim

 

Delta or wye. Which ever way works so use which ever fits your line voltage best.

Yes ~10 uF per hp on each capacitor bank generally works the best but depending on the motor efficiency and working load you might get by with less or it may take more being I have found that it can vary a fair amount depending on the motor and load its running.

 

Yes I am familiar and then some.

All you need to know and more.

http://www.electro-tech-online.com/threads/3-phase-converter-schematic-miller-system.100563/

Hi,

First thank you for your prompt reply. The link above certainly takes me to the best information I have come across by far.

I have t

Delta or wye. Which ever way works so use which ever fits your line voltage best.

Yes ~10 uF per hp on each capacitor bank generally works the best but depending on the motor efficiency and working load you might get by with less or it may take more being I have found that it can vary a fair amount depending on the motor and load its running.

 

Hi,

First thank you for your prompt reply. The link above certainly takes me to the best information I have come across by far.

I have t

Many thanks for your help. I have a few projects on the go at the minute, including replacing our full kitchen and water heater, so cannot give this project all my attention at the moment. I will order up the capacitors and set things up, get the motor running and come back to let you, and others, know how things went and how I get on.

Again, many thanks for your help and guidance.

Take care,

Jim

 

Good to know. As I have come to understand it there are hundreds of systems that have been built on my write up specs now and very few have ever had any problems with it that didn't come from having adequate power sources or bad motors/components.

I have personally been running on this design for more that 20 years now since I first figured it out in college. The biggest active unit I have is my 15 Hp shop air compressor and that's been in service for about 10 years now with no real issues other than a breaker burnout a starting capacitor going bad few winters ago so far.