air compressor magnetic starter/relay single phase

[hr3]

This is going to be interesting

 

[ddmckee54]

ld1:

Regarding the size of the VFD, that will depend on whether you are buying a specialized 1 phase to 3 phase VFD, or a standard 3 phase VFD that can be run on 1 phase - some manufacturers will allow you to do this.

With a 1 phase to 3 phase VFD you will buy the VFD to suit the motor that you want to run. In this case you'd want a 7.5Hp VFD.

With a standard 3 phase VFD running on 1 phase power you need to de-rate the VFD. The rated Hp. of the VFD would need to be divided by 1.73, I'd just divide it by 2 to be on the safe side. In this case with a 7.5Hp motor you would need a 15Hp VFD in order to safely handle the load on a continuous basis. I realize that compressors are not continuous loads, so YMMV.

I'm just saying that the 15Hp VFD will run the 7.5Hp motor 24/7 with no problems. I design control systems for industrial equipment that HAS to run 24/7 so I tend to be a little conservative about these things.

Don

 

[LD1]

That's why I questioned what he actually used. If he is getting by with a 10, or went to a 15.

No difference in a single to 3ph vfd or just a standard 3ph vfd. Just the sticker that gives the HP rating. And more money too.

Most drives will fault out if trying to use too big of a motor. Not a matter of being slightly too small and failing prematurely if used 24/7, it just simply won't start the motor. I tried to run a lower amperage small frame 7.5. HP motor with a 5hp drive and it just wouldn't work.

By small low amperage I mean one that is about right in the middle of a normal 5hp and 7.5hp as far as Fla goes. Don't remember the specific numbers though

 

[5030]

Everything you need is at Grainger Industrial Supply - MRO Products, Equipment & Tools

 

[disney]

Sorry for the delay. I had to run out, and I just got back. I have been trying to add the pictures for about 15 minutes, even tried adding them 1 at a time, but no luck any ideas?

 

[disney]

I will review the replies as I can. (thank you all..so much) but to refresh/restate some info. I bought the compressor (have not yet been able to run it) with a 10hp 3phase motor installed (wired for 460). I have not issues keeping the current motor installed if I can buy a product (VFD, or otherwise) that would allow me to run the current motor from a 50a 230 single phase power source. The link that someone provided (thank you) had a price of over 700$.

 

[hr3]

Let me throw this old school into the mix.. https://www.google.com/url?sa=t&rct...se.php&usg=AFQjCNFOEhcHJaNni_4Czf9tglHXrAi_Lg

 

[LD1]

I am afraid that unless you get a deal on a used one, you are gonna need to spend the $800 to get a vfd to work.

There is no cheap solution. Price a 10hp single phase.

As for the pics, try resizing them smaller

 

[Redneck in training]

Here is a VFD for 300.
7 5KW 380V 19A VFD Variable Frequency Drive Inverter CE for CNC Hot Product | eBay

 

[disney]

Ill go try to take a few pics, but I don't have the best light, so they may not come out great. I will continue to be open to the VFD idea, but odds are I will be just ordering the new 5ph single phase motor, and changing the pulley. The pump is rated for 5, 7.5, and 10 hp motors. So the pump should be ok with 5hp, once I get the contactor and thermal protection sorted out. I would like to give a big thanks to everyone that is replying to this post.