Phase Converter questions

[Kevin54]

Phase Converters.

Hopefully I am getting my mill hooked up this weekend. I have a 3 horse rotary phase converter that I am going to use in conjunction with it. The question I have is.....how far can I have the phase converter away from the mill, or can I at all? The guy I bought the mill off of is running a few pieces of equipment and each piece he has, the converter is right beside the machine. I'd rather not have the phase converter beside this mill. Can it be placed around 30' from the mill?

The next question I have is......the 220 I have in the garage is dedicated for my air compressor. It's an 80 gal. 5hp. IR compressor. The Lagun mill has a 2hp motor, and the P.C. is 3hp. The 220 in the garage is on a 30 amp breaker. Can I tie into this breaker and run the converter and the compressor both off of it? By that I mean running both off of the 30 amp breaker in the box and the phase converter running off of the same breaker.

The compressor will be on it's own line with no P.C., But I am wanting to know if the mills phase converter can be put on the same breaker as the compressor.

Now this brings up another question. I went to a garage sale and was talking to the guy that had it. He had a lot of machinery in there. I asked him if he had three phase out in his garage and he said that he didn't. I told him I picked up a mill and he told me I should forget about using a phase converter and to purchase a VFD for it instead. He said that with a VFD, there is no need to run a phase converter and the 220 single phase hooks in through the VFD and to the mill. He was busy so I really didn't get a chance to go over it in detail. Can someone explains in dumbed down terms how this works?

Last question.....for a little while .....I will more than likely hook up the phase converter for the time being, and if a VFD would work out, I may switch it over at a later time. But if I decide to get a lathe here in the very near future, I will be running it off of the phase converter also. Without plugging a machine in and unplugging it for another machine, is there something like an A/B switch I could use to swap power between machines?

Thanks for any help anyone can give me.

 

[rsanter]

You can have a lot of distance between the converter and the machine just be sure the wire is big enough tonavoid losses....
May guys will have a RPC under the bench in one corner and run a line around the garage to connect to all the 3ph equipment. No problem

If you use a VFD that has the rating to convert from single to 3ph you do not need a converter and I prefer to use a VFD instead of a converter. For example if you get a VFD that is rated for 3hp if you are using 3hp in, 3pm out. It will be derated to say 2 or 2.5hp running single in and 3ph out.
A regular converter will have a 33% loss of HP rating. A rotary converter will adsorb the losses in the converters motor so you will have almost full rated power on your machine and a VFD will give you 95% or better of full rather power on your machine. Nothing wrong with using a RPC but today it is more economical to buy a VFD verses a RPC.

You can have both the compressor and the other equipment on the same circuit but I do not believe it is code. I do the same thing as I know I can only have one going at a time so for me it works as I know what's going on with only me in the shop

Bob

 

[OccupantRJ]

Kevin, the added plus of a VFD is that you get variable motor speed with it. I have 2 rotary phase converter capabilities, but I am thinking about going with VFD's now. On my Bridgeport I would need two though, as my table motor is 3 phase, and it needs to run constant speed, whereas the spindle would be nice to have variable. Not a deal breaker, as I am used to using a step pulley machine anyway. I could also run the table with a static converter, as I have 2 of those, and run the spindle with a VFD. So many choices....

 

[930dreamer]

I run the 3 phase out of the converter to a disconnect for the air compressor, and another line out of the converter to a disconnect for a Baldor grinder. I'd look at a 5hp or 7.5hp if you didn't go with a vfd, for other machine add ons in the future.

 

[NASTYZEN]

Phase converters are usually noisy...Put it as far away as possible and mount it on rubber.

 

[theoldwizard1]

Phase Converters.

Hopefully I am getting my mill hooked up this weekend. I have a 3 horse rotary phase converter that I am going to use in conjunction with it. The question I have is.....how far can I have the phase converter away from the mill, or can I at all? The guy I bought the mill off of is running a few pieces of equipment and each piece he has, the converter is right beside the machine. I'd rather not have the phase converter beside this mill. Can it be placed around 30' from the mill?

With the proper size wire, yes.

The next question I have is......the 220 I have in the garage is dedicated for my air compressor. It's an 80 gal. 5hp. IR compressor. The Lagun mill has a 2hp motor, and the P.C. is 3hp. The 220 in the garage is on a 30 amp breaker. Can I tie into this breaker and run the converter and the compressor both off of it? By that I mean running both off of the 30 amp breaker in the box and the phase converter running off of the same breaker.

Can you ? Yes. Will it meet NEC ? Don't know.

Now this brings up another question. I went to a garage sale and was talking to the guy that had it. He had a lot of machinery in there. I asked him if he had three phase out in his garage and he said that he didn't. I told him I picked up a mill and he told me I should forget about using a phase converter and to purchase a VFD for it instead.

Not an expert, but here is my understanding of a VFD. Think of it as the electronic equivalent of a rotary phase converter, with a bonus. Single phase in, 3 phases out. Because it is electronic, it is MUCH more efficient. The bonus is a VFD will give you variable speed, with full power at all speed.

Basically a typical AC motor is designed to work a one speed and that speed is some fixed multiple of the 60 Hz AC we use in the US. The VFD (Variable Frequency Drive) synthesizes the 3 phase so it can synthesize any frequency, and therefor speed.

Last question.....for a little while .....I will more than likely hook up the phase converter for the time being, and if a VFD would work out, I may switch it over at a later time. But if I decide to get a lathe here in the very near future, I will be running it off of the phase converter also. Without plugging a machine in and unplugging it for another machine, is there something like an A/B switch I could use to swap power between machines?

What you are looking for is a 3 pole double throw safety switch. I think they are called "safety" switches because the contacts are in a heavy metal box that will contain any arcs. (Switching high voltage and high current WILL make arcs/sparks !) They do make them. They are expensive.

 

[larry_g]

A regular converter will have a 33% loss of HP rating.

Bob

I assume that by REGULAR CONVERTER you are referring to a static converter and not a rotary.

It is not usual to have any switching of loads or machines on the output of a VFD. Each VFD will be programmed for the machine that it controls.

I have the output of my rotary going to a panel and from the panel I run wiring to my machines. The control box is in the shop and the rotary is out in the main shop where the noise is controlled.

lg
no neat sig line

 

[930dreamer]

http://www.ehow.com/how-does_5002241_a-vfd-work.html

 

[rsanter]

I assume that by REGULAR CONVERTER you are referring to a static converter and not a rotary.

It is not usual to have any switching of loads or machines on the output of a VFD. Each VFD will be programmed for the machine that it controls.

I have the output of my rotary going to a panel and from the panel I run wiring to my machines. The control box is in the shop and the rotary is out in the main shop where the noise is controlled.

lg
no neat sig line

Yes, I mean static converter

Bob

 

[Norcal]

Single phase input VFD's do not need to be derated, if they are rated for 3 HP you have 3 HP, the hardest part is deciphering the manual 'cause some are written in Chinese & translated into English. I have a couple that are being used on 200V 3Ø tools, (208V) they are are single voltage & line voltage is a solid 240V+,so they would not like the output straight off a RPC. A VFD will give speed control in addition to being a phase converter. A quick note though, over 3 HP, AC drives w/ single input is rare & expensive, one starts going into territory of 3Ø input drives where phase loss protection can be disabled & the drive is derated 50%.

I bought a new GE/Fuji 3 HP drive for under $200 shipped on eBay.

 

[eriksalo]

I have had good luck with 3hp VFD phase converters. Overall, they are affordable and much less trouble and noise than a real rotary converter. VFD's get expensive if you need larger sizes. For example, I have a 25hp milling machine and a VFD for that would be expensive.

You can run a rotary phase converter relatively far away from the load as long as the conductors can handle the load.

I put my phase converter on a dedicated circuit. However, I don't know why you can't run multiple loads (phase converter and other thing) on the same circuit. I don't think it's possible to interfere with the supply voltage, it come from the power plant....

 

[bigguns69]

See my post about VFD install on Enco (Bridgeport) Mill as an alternate choice. The VFD option gives you some feature upgrades that a rotary will not.

http://garagejournal.com/forum/showthread.php?t=160811