Ask Me Help Desk - What's more energy efficient single phase or 3 phase and what's harder on the equip?

What's more energy efficient single phase or 3 phase and what's harder on the equip?

Hello,
I would like some advice from anyone willing to offer. I'm starting an ice cream business and I'm collecting used soft serve machines. Apparently, there are used machines configured for single phase and 3 phase 208V 240V etc... I would like to know which phase a voltage is more economical and which is harder or more damaging to the equipment. I appreciate all your opinions.

Thanks :)

Ans too long to post from phone. Stay tuned

Three phase is definitely easier on equipment and actually slightly more efficient.
One big plus of three phase is that you can run a smaller circuit (albeit with one more conductor) to a given load. The wattage consumed is about the same (you pay for watts) but the amperage is lower with three phase.

That said, you should NOT be buying your equipment based on this. You need to find your place first, THEN buy your equipment based on the available service.
You may not find a place that fits your needs that has a three phase service, or many of the places you find might. You never know until you start looking.

You cannot just "add" three phase to a building. Unless of course it is available in the area and you are willing to spend many thousands to upgrade the service.

I would like to reaffirm what Stan explains. See what your building has for incoming power and match the machines power requirements to that.

The issue between single phase and three phase efficiency is really insignificant.

Being soft serve, I went to Taylor, that most soft ice cream machines, and chose a typical unit:
http://www.taylor-company.com/product/s_pdf/s0741.pdf

Now the electrical specs are do not state exact loads, other than the BTU's.

It does appear that you may want to consider using water cooled, as the min circuit amps is lower.

I will always recommend three phase when available, as long as equipment is available in 3 phase.

We had a discussion about saving money for some other type of business using mixers. The type of electric rate pays an important part especially if you have one based on peak power in a 15 min period on do lots of starts and stops.

As usual, I bring out an entirely different angle. Usually 3 phase is the way to go if it's available which is almost a no-brainer generally.

BUT, just because the machine has a 3 phase motor on it, YOU CANNOT ASSUME that the machine requirements are 3 phase power.
Variable speed drives will typically use 3 phase motors or various types. They can have a single phase input "from the wall".
So, buyer beware: Look at the nameplate.

I can also add:
< 1/2 HP use single phase usually
> 5 HP use 3 phase

Between 1/2 and 5? You need to look at other factors.

Please explain this:

Quote:

Originally Posted by KeepItSimpleStupid

BUT, just because the machine has a 3 phase motor on it, YOU CANNOT ASSUME that the machine requirements are 3 phase power.

If I have a unit with a 3 phase motor, why can I not assume the power requirements is 3 phase?

What shall I assume?

Because of these things:

3 HP 230 Volt -- USE AS A PHASE CONVERTER PLUS GET VARIABLE SPEED, Model JNEV-203-H1, Single Phase Input ONLY, Three Phase Output, ac drive, vfd, afd, frequency drive, drive, variable frequency drive, inverter, adjustable speed drive - Dealers Indust

Use only the appliance or machine nameplate data ONLY.

Absolutely must use nameplate data, I cannot agree more.

I still don't see the connection between the statement:

BUT, just because the machine has a 3 phase motor on it, YOU CANNOT ASSUME that the machine requirements are 3 phase power.

And now even more confused with a VFD that can be used as a phase converter.

If a unit has a 3 phase motor, why should I be careful of assuming it may not need 3 phase?

If a machine has a 3 phase motor, then it's power requirements is that it needs 3 phase power, there can be no other reasonable assumption.

Seems we are getting off topic to the posters question, but I need to see this cleared up.

Quote:

Originally Posted by tkrussel

If a machine has a 3 phase motor, then it's power requirements is that it needs 3 phase power, there can be no other reasonable assumption.

sort of. It just doesn't need it from the wall.

I had an application where someone wanted to BUILD a spiffy mixer, so they got a 120 to 240 step up transformer, one of these sorts of speed controls of VFD's (20 years ago they were not called VFD's) and a 3 phase 240 volt motor.

So, we have:

nameplate says 120V, if it had one.
Motor is 240, phase is 3

So, you cannot assume that a simple mixer is 3 phase. In fact it could be wired as 120/240 single phase.

Now let's look at some other things. The web has been less than helpful.

Your new veriable spped 96% efficient furnace will have a electrically commutated motor in it to control the speed.

Your treadmill probably has an electrically commutated DC motor because it's easy to measure torque.

Your High efficienct variable speed washer will also have an electrically commutated motor. I'm just not sure if it's DC or AC.

What I am saying is this:

It is possible that an ice cream machine maker could incorporate a VSD. He could make the power requirements 120 or 240 single phase. This would give hime noce control over the speed, but torque might be a bit hearder to measure.

Now he could also make an entire 3 phase unit and again may use a VFD but with a 3 phase input.

Just like our furnace has things that operate on 24 VAC and 120 VAC. It also has things may be electrically commutated.

Just looking on the web, I found this:

http://www.taylor-company.com/servic...04op_05-94.pdf

So, this is basically a compressor and a motor with selectable speeds with either 120 or 240 V single phase operation.

In all likelyness, the compresser nameplace would match the input voltage required.

I ran into a piece of equipment which had a 70 A 3 phase input and I could not figure out why. The phases went to separate primaries on the transformer so you ended up with a ripple frequency of 180 Hz. I think it used a half-wave rectifier. It was a high voltage, high current power supply. Like 13 KV at 1 amp. It also had taps for 208 or 240 volts.

Weird things, can and do happen.

Someone asked an electrician to wire a similar piece of equipment that didn't know what they were doing and didn't include the neutral. This piece of equipment put a breaker in the neutral leg as well. It needed 3 phase with neutral and ground.

Then some other idiot caused an electrician to specify a 240 V panel for some equipment when all they had to do is change a tap. They added 208 to 240 V step up xformer to accommodate the equipment. Daah! He was paid 4x what I was and NOT an electrician, but he earned a PhD in physics.

The real point of my post, is to use only nameplate data and read it closely. Some equipment may require a neutral and others may not.

We should also mention that 3 phase systems may require protection against losing a phase or differences in phase voltages or motor control stations, disconnects etc.

There is a fine balance to select what's required for a protected machine. You need to include the cost of the protection devices as well as the productivity lost.

Having a 5 HP 3 phase 208 lathe in a residence would cost you a bunch of bucks to be able to use it on standard 240/120 power.

So would a 3 phase ice cream maker in a building that didn't have 3 phase.

Again, with this I could not agree more:

Quote:

Originally Posted by KeepItSimpleStupid

The real point of my post, is to use only nameplate data and read it closely.

As even listed in Taylor instructions, must refer to the nameplate.

This being a refrigeration unit, the nameplate is the final word, very typical with all refrigeration equipment.

The rest of your post is clear as mud.

This thread has gotten way out of topic, we all agree, I believe, that if 3 phase is availalble then the units purchased should be 3 phase. That is all the poster wanted to know, in my mind.

I am done.

I'll admit that I didn't read all that, but I will say I have never seen a piece of 3-phase equipment that had a built in phase converter. I see no reason to do this.

KISS, I am curious what they called VFD's in your neck of the woods 20-years ago?

Speed controls

Flex, do you have your location yet, and is three phase there already? If it is, fine. But if not it can be run there by the power company... but it could cost SEVERAL thousands for them to do it for you. There are phase adders that work, but those also are pricy. After you get the building, then research your needs. I don't know how large your business is, but unless it's a large operation, 3 phase equipment is probably overkill. Let us know the details please, and we can confuse you more.

Advatage& application of 3 phase induction motor using single phase supply? Can we use higher rating 3 phase motor on single phase supply ?

Only if you use a single phase to 3 phase converter.

3 Phase Converter Info- Sales- rotary phase converter, static 3 phase rotary converters.

Quote:

Originally Posted by stanfortyman

Three phase is definitely easier on equipment and actually slightly more efficient.
One big plus of three phase is that you can run a smaller circuit (albeit with one more conductor) to a given load. The wattage consumed is about the same (you pay for watts) but the amperage is lower with three phase.

That said, you should NOT be buying your equipment based on this. You need to find your place first, THEN buy your equipment based on the available service.
You may not find a place that fits your needs that has a three phase service, or many of the places you find might. You never know until you start looking.

You cannot just "add" three phase to a building. Unless of course it is available in the area and you are willing to spend many thousands to upgrade the service.

yeah but:
three phase motors actually do use much less wattage. i did a test with them and a load- compared to a washing machine load- the three phase was 68% more efficient. it also saved 588 watts. so it would be much better. it is also more compact and will be better with the equipment.
on the other hand, you have to somehow convert the single phase power from the wall into three phase power for the motor to run. average wall outlets are single phase power.

Smartz... this is a 4 month old post. And your 68% number is not accurate. The best and often the only reason to use 3 phase, higher voltage circuits is to have smaller conductors and / or longer wiring runs. Ohm's law doesn't change... ever.

Quote:

Originally Posted by smartz123

on the other hand, you have to somehow convert the single phase power from the wall into three phase power for the motor to run. average wall outlets are single phase power.

Who is talking about "average wall outlets"?? The OP (several months ago) was talking about ice cream making equipment, and never mentioned his service voltage. He may very well have (had) 3-phase.

Also, your point about converting is a major one. THINK about it. If you have to convert single-phase into 3-phase, don't you think there will be loss involved? Even added consumption? Won't this offset any savings you might find using 3-phase equipment? It will. In fact it will wind up costing MORE.

I also agree with Missouri, your 68% number is way off base.