3 phase "101"

[joe milana]

I've been trying to find info on using 3 phase equipment in a residential setting. Beyond knowing that if I want to run a 3 phase piece of equipment, I need a phase converter. What I don't understand is;

Will the equipment produce the same power as it would if wired true 3 phase? Is it hard on the equipment?

How much power does a phase converter consume?

How big can I go if my service is 100amp? 200amp?

What other questions should I be asking?

[Hugh Jardon]

Have you looked into just getting a 3 phase supply? You almost certainly have 2 phases already...

[joe milana]

Have you looked into just getting a 3 phase supply? You almost certainly have 2 phases already...

Don't think it's possible in a residential area, and if it is, it is cost prohibitive.

[Kent A Bathurst]

I've been trying to find info on using 3 phase equipment in a residential setting. Beyond knowing that if I want to run a 3 phase piece of equipment, I need a phase converter. What I don't understand is;

Will the equipment produce the same power as it would if wired true 3 phase? Is it hard on the equipment?

How much power does a phase converter consume?

How big can I go if my service is 100amp? 200amp?

What other questions should I be asking?

If you want to run only a machine powered by less than 5 hp, then you can use a VFD (variable freq drive) instead of a phase converter, to drive that one machine. As you add more three-phase machines, you can keep doing the same thing, but the costs go up to where it isn't best $$$$ choice. The issue with 5hp is that, at that point, the VFD needs three phase in to provide the var freq drive with three phase 5hp out. One cool thing about the VFD approach is that, as one example, you could get a three phase singel speed shaper, slap the VFD in front of it, and now you have a variable speed shaper.

AFAIK - VFD and a rotary phase converter produce the same output power as input. A static phase converter is cheapest solution, but you lose power (30%?) on the output side. The machien itself doesn't know diddly about the single-phase source - it is just living life on teh three-phase side and couldn't care less.

Your inbound service mox nix. The correct question is: How much three phase power will you want by the time you are done? If you intend to drive multiple motors that total 25hp, for example, then you need a phase converter that will generate that much power and you need a single phase circuit that will send the correct amount of power to the converter. For a phase converter, you install a new circuit out of the box that goes to the converter, then circuit(s) from there to your machines.

AFAIK - VFD or rotary consume no power (or negligible power) on their own.

I have come close on 2 occasions to getting a three phase machine, but the deal killer is that the person selling did not have three phase, so I could not go look at the machine and actually turn it on. No thanks.

[Steve Bracken]

If you want to run only a machine powered by less than 5 hp, then you can use a VFD (variable freq drive) instead of a phase converter, to drive that one machine. As you add more three-phase machines, you can keep doing the same thing, but the costs go up to where it isn't best $$$$ choice. The issue with 5hp is that, at that point, the VFD needs three phase in to provide the var freq drive with three phase 5hp out. One cool thing about the VFD approach is that, as one example, you could get a three phase singel speed shaper, slap the VFD in front of it, and now you have a variable speed shaper.

AFAIK - VFD and a rotary phase converter produce the same output power as input. A static phase converter is cheapest solution, but you lose power (30%?) on the output side. The machien itself doesn't know diddly about the single-phase source - it is just living life on teh three-phase side and couldn't care less.

Your inbound service mox nix. The correct question is: How much three phase power will you want by the time you are done? If you intend to drive multiple motors that total 25hp, for example, then you need a phase converter that will generate that much power and you need a single phase circuit that will send the correct amount of power to the converter. For a phase converter, you install a new circuit out of the box that goes to the converter, then circuit(s) from there to your machines.

AFAIK - VFD or rotary consume no power (or negligible power) on their own.

I have come close on 2 occasions to getting a three phase machine, but the deal killer is that the person selling did not have three phase, so I could not go look at the machine and actually turn it on. No thanks.

Good info :)

It's worth noting that secondhand 3-phase machines will give lots more machine for the money. To start with, you generally will not be competing with other Hobbiests, as they stay away from 3-phase.

Run the numbers, but decent VFD's for 2hp are starting at around $200. Add that to the machine price and work it from there, remembering that you will usually be buying industrial quality machines that were never build down to a price for the home market.

[Gary Click]

You likely better served by a Variable Frequency Drive (VFD). These are used on a one drive per machine basis and can be sized to suit the specific motor. The 3 phase current is electrically cleaner and better shaped than mains power also.

Many if not most small units will accept single phase current (even if they say they are three phase input, for these you must derate the output since single phase has less power available that three phase for the same curent rating) and output true three phase current. They alos have the added benefit of current inrush control (soft start), variable speed control, lost leg protection and rotation control. Most units also emply a start/stop circuits functioning the same as a magnetic starter.

The theory of operation is actually very simple. The VFD first taking the incoming current and rectifies it to pure Direct Current and places it on the Drive Buss. Using large transistors or similar devices the DC is inverted to Alternating Current of some frequency which can be controlled by the user. This results in an AC ouptut but is still single phase. To acheive true three phase there are two more identical circuits which also invert the DC to AC but it is shifted by in time to construct the true three phase current. There are several other things that can happen in the drve as well but this is the major events.

I have found that Allen-Bradley Bulletin 160 drives have done well for me. Althouigh considered absolete they do a good job and can be as cheap as tomato stakes on the used market. I also have a 2hp Mitsubishi on my CNC mill and a couple of Automation Direct units kicking around on other things.

Three Phase handles things like variable speed, direction reversal much better than single phase and three phase motors don't have starting windings, centrifugal switches and capacitors to deal with.

gary

[Bruce Page]

I’m no expert but it depends on what you are running. A commercial CNC machine will require good, filtered, three phase power. I know of a couple of local garage shops running small Fadal CNC machining centers off of high end rotary phase converters. IMO a rotary converter is the most reliable “full time” option.
I have a 3hp non-CNC milling machine and a 5hp engine lathe that I run off of a Phase-A-Matic static converter. There is some power loss, but I have never been able to tell much difference – and I made a living running three phase versions for many years. People will tell you that the static converter is bad for the motor and it may well be, but I have been running this setup for 15-20 years without even a hiccup.
Again, if I were running full time I would use a rotary but for hobby use this setup has worked well.

[joe milana]

Great info so far! I've got my eye on two new machines. Saw in the 5.5hp range and a shaper in the 7.5hp range. I will never run more than one machine at a time. My understand is that I can run all machines through the same converter if I use a rotary type, and if this is true, it open a whole new market of used machinery!

[Rick Fisher]

http://i335.photobucket.com/albums/m455/jokerbird_photo/Phase%20Perfect/P1150303.jpg

I run a Phase Perfect Converter .. Its wired to a 100 amp 220V breaker.

The power output is 240,240,242. So its within 1%.

The converter sits between a single phase and three phase panel. Presently there are two machines wired to the three phase panel.

From 100 amps, This converter will produce 55 amps of 220V PH3 power.
If there was no power loss or power used to run the actual converter, the ratio from single phase to three phase would be 1.73.. However, no converter is perfect.

[Steve Rowe]

I have been running a 10 HP Kay rotary phase converter for about 3 years in a residential area. Basically, a rotary phase converter acts like a rotary transformer to create the 3rd leg. The 3rd leg is called a stinger leg and with no load applied, the voltage will run high (on mine about 270VAC with the other legs at 242VAC). Just make sure your control circuits are not on the stinger leg. Once loaded, the stinger leg voltage goes to about the same voltage as the other two legs and gives a fairly good balance.

I run a 7.5 HP saw with an additional 1 HP scoring motor. While not done in my shop, this same phase converter size also powered a 5 HP dust collector at the same time. The key is to not start a motor larger than the phase converter is capable of starting. Once started, additional motors can be started up to the maximum capability of the converter. My Kay MA2BR largest HP to start is 10 HP and will run up to 30 HP worth of load. You just can't start a motor larger than 10 HP. Be wary as this is applicable to Kay converters which are very conservatively sized. Other manufacturers that I looked at play games with sizing and tell you that to start a 10HP load, you need to buy a 20+ HP converter. I run the Kay on a 60 amp circuit.

I really like Ricks' PhasePerfect and I almost went this route myself. I have heard many good reports on this converter. The downside to this type of converter is that you need to buy the largest size you need upfront as you can not parallel additional units in the future like you can a rotary. This was the primary driving factor for me going the rotary route.

I have a disc sander that I run from a VFD. It is 2 HP and gives me the ability to slow that 20" disc to a more suitable speed than 1725 rpm. It works well but it sure puts out a high pitch whine. I wouldn't consider trying to run heavy loads on this type of converter.

In doing research, I found the sales staff at Kay Industries, American Rotary, and PhasePerfect extremely helpful and knowledgable and several of them are electrical engineers. If you are serious about this, give one or all of them a call.
Steve

[Steve Rowe]

Don't think it's possible in a residential area, and if it is, it is cost prohibitive.
It is possible in many areas and you are absolutely correct that it is cost prohibitive. A buddy just built a shop last year and checked into this. His cost for doing so was $35,000. On top of that, he would have had to pay the industrial rate for power instead of the residential rate.

[Rick Fisher]

That is the opposite of how the digital works. With the digital, I can run the 4hp jointer and fire up the Wide Belt.. (which is 12hp) .. no problem.. I cannot however exceed 55 amps..

I suppose the idling amperage would be lower on a bunch of tools.

Start up amperage is different. The digital will allow well over 100 amps for very brief amount of time. I am of the opinion that most 3 phase motors have lower starting amperage than single phase ?

Either way, a three phase system in your shop is awesome. Its liberating.. you can simply slap in a breaker and wire up most used machinery..

[Gary Click]

From 100 amps, This converter will produce 55 amps of 220V PH3 power.
If there was no power loss or power used to run the actual converter, the ratio from single phase to three phase would be 1.73.. However, no converter is perfect.

Thats actually extremely good. The theorical perfect power conversion (that's power as in watts not current as in amps) for 100A 1ph would be 100A/(Sqrt 3) = 57.735A. Pretty close to 55A.

If I could be so brash what does a unit like that cost. A lot of 3ph machinery become unloved orphans because of the power demands.

gary

[joe milana]

Wow, this is a lot of info, but I think I'm getting the concept. OK, here is a question:
Supposing I have a 10hp 3 ph 220v motor and the electrical specs say it draws 16A. How many amps will this motor draw from the 220v panel?

[Rollie Meyers]

VFD's over 3 HP can become cost prohibitive w/ a single phase input, I was looking at a VFD for a 5 HP 3Ø motor & could buy a new 1Ø motor for $100 less then a 5 HP 1Ø input drive. Above 3 HP the input is 3 Ø input only, unless they have provisions to disable phase sensing in the input with the programming of the drive.

I later decided against buying the machine, for the rest of the story.

[Rick Fisher]

Gary..

I bought the Digital from American Rotary. The fella there was very helpful. If my memory serves, it was $4600.00

Its rated at 97% efficient.. If I hook it up to a 125 amp breaker, it would produce a maximum of 64 amps.. That's all its got.. So at 125, it should produce 72 amps.. I think the voltage regulation drops it to 64 amps.

Mine is model # PT355 .. rated at 20hp.. It will actually run 20hp.. I did a bunch of reading on converters and a buddy of mine, who is an electrical eng. did a bunch of reading as well.. I picked it because it was CSA approved, and is very quiet.. It draws 200 watts idling.. I just let it run all day when I am in the shop.

I think its overkill for home use, but who knows what I will want to do with it in the future ? Perhaps CNC technology will continue to plummet in price? I think you can also run a CNC on a good rotary.. like the one mentioned above, but they cost more than the cheap ones too..

[Joe Jensen]

I think the 100A Phase Perfect is between $4-5K

[Brian Ross]

I started with a 20 hp American Rotary phase converter and use it to power a 10 hp slider and a 5 hp DC. The phase converter is hooked to a 60 amp breaker in my 100 amp panel. I recently bought a used SCM widebelt sander that has a 18 hp main motor and a 1 hp motor for the belt. It is also 3 phase. American Rotary advised that it would be best to add a second 20 hp phase converter as the start up current draw on a wide belt is quite high. My second rotary phase converter cost me $1200.The first one has been running for 6 years with out a hiccup. American Rotary has excellent 24/7 technical support and great people to deal with. Their website has a lot of good info relating to phase converters.

Brian

[Chip Lindley]

Wow, this is a lot of info, but I think I'm getting the concept. OK, here is a question:
Supposing I have a 10hp 3 ph 220v motor and the electrical specs say it draws 16A. How many amps will this motor draw from the 220v panel?

Joe, my experience is with ARCO rpc's. From their specs online, the 10hp. Model B runs on a 50amp circuit on 230v. from your panel. Idling, it consumes about 7a. Maximum load is 40a. Your 16a. 10hp. motor could draw up to it's maximum 16a. before it's overload relay trips. Other motors could be run also, up to 10hp. if started one at a time. Usually one machine and a DC is all that runs in a home shop.

Lots of good information on this page:

http://www.arco-electric.com/InstallationGuide.aspx (http://www.arco-electric.com/InstallationGuide.aspx)

[joe milana]

Lots of good information on this page:

http://www.arco-electric.com/InstallationGuide.aspx (http://www.arco-electric.com/InstallationGuide.aspx)



Ah, more info. Thanks! I just found this on the American rotary website (which has lots of info):

2.1.5 WIRE SIZING RECOMMENDATIONS
It is important to have adequate single-phase electrical service. The actual single phase current
that will flow through the converter is 1.73 times the three-phase current. The National Electric
Code requires 2.5 times the three-phase current to allow for starting current and a margin of
safety. This is a good, conservative calculation to determine your single-phase branch circuit
wire size and breaker size.

I'm starting to grasp the 3ph concept here. It's not really that complicated, besides, my neighbor is a retired electrical engineer and would LOVE to come over and help. The complicated part is getting him to leave...;)

[Bobby O'Neal]

Just a thought, but the cost of getting three phase power to your shop may not be that much. if you have three phase lines on your road, then you only have to pay for getting a 3ph service. That is, buying three transformers and quad-plex wire to feed from them. That's how many power companies do it. If you are a way from the road and they'd have to build a 3ph tap to you and then your service on the end of it, that would be pricey. But the transformers should be less than $1000 each and the wire is not too much.

Bobby