mike93lx
ALLIANCE MEMBER
I just want a video of your meter if you ever get this running.
Using weaker phase converter to slow down compressor?
- Thread starter BenKlesc
- Start date
TRWham
Well-known member
But it will hum on a single phase supply because it does not know the words.
Yeah, but it's kinda monotonous. 60Hz is a really sharp A, or a slightly flat B.
alfredeneuman
Well-known member
Ben,
Don't buy any more until you let a competent electrician in on your scheme.
Don't buy any more until you let a competent electrician in on your scheme.
Strouty
Well-known member
OK, this took the thread right off the rails. Originally I was behind you, but you need to stop, take a deep breath and start listening to the nay sayers.
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sberry
Banned
Electric is probably cheaper to operate. But that is rather irrelevant in the grand scheme. 2 7.5 comps would be as easy and they don't even got to be real good ones. Buy them new, hook up, blast today.
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alfredeneuman
Well-known member
He hasn't even mentioned what size his service is. For all we know it could be 100A, house included.
He's already proven that he is clueless as to the hooking up of anything
He shouldn't spend a cent more until he finds someone with the knowledge and skills to do the work.
Ohhhh come on, He needs to spend some more $$$. I was going to offer to sell him the mag starter from my 20hp Quincy 390 compressor, as I have no need for it now that its running of a VFD
BTW it now starts and runs on a 20amp breaker!William.....
Strouty
Well-known member
Ohhhh come on, He needs to spend some more $$$. I was going to offer to sell him the mag starter from my 20hp Quincy 390 compressor, as I have no need for it now that its running of a VFD
William.....
????? How is that possible, are you doing common core math to arrive at that amperage?
I'm curious too, since even on 480V a 20hp motor is around 25A
Well I'm cheating slightly
It's not running at its full 60hz/1725rpm... at full speed ( tank empty) it will start just fine but after it gets close to the (current) 150 psi unloader pressure (after running for several min.) it will pop off the breaker.
If I run it at a slightly slower RPM it works just fine on the 20 amp breaker and will run for hours unloading and pumping up as needed.
William....
7635tools
Well-known member
First of all you wouldn’t try to start a 40hp motor off a 40 hp phase convertor. Any motor off the phase convertor needs to be smaller than convertor. Yes I can start a 10 hp motor on my big lathe no problem.
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100 amps? 200 amps?
No way, it is 35@230V. 18@460V.
With a phase converter, I would be running around 50 amps.
Found a sticker on the air compressor for a local company that services compressors, so I am using them.
I am having an electrician install two 220V outlets from my breaker and running it to my garage.
Oh it'll get running. I'm buying the phase converter today.
I'll be sure to post updates!
No way, it is 35@230V. 18@460V.
With a phase converter, I would be running around 50 amps.
Found a sticker on the air compressor for a local company that services compressors, so I am using them.
I am having an electrician install two 220V outlets from my breaker and running it to my garage.
Oh it'll get running. I'm buying the phase converter today.
I'll be sure to post updates!
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wyliesdiesels
Well-known member
what are the outlets for?
Compressor & Welder.
Strouty
Well-known member
What phase converter are you buying?
Not sure you understand that this is only if you have three phase power, not single phase being converted. The phase converter will take more amperage for sure.
Also why would you step up your voltage, the motor will run on the lower voltage.
100 amps? 200 amps?
No way, it is 35@230V. 18@460V.
Not sure you understand that this is only if you have three phase power, not single phase being converted. The phase converter will take more amperage for sure.
Also why would you step up your voltage, the motor will run on the lower voltage.
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If I wanted to run on less amps.
Not doing that anymore though, I'll just rewire the motor.
I also just confirmed, I have a 200 amp breaker box.
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So how many more amps would it be running on single phase? Is it a significant increase? If I increase the voltage, I can lower the amps. My phase converter I will be buying works in both 460 & 230. Then in that case, maybe it would be worth using a step up transformer to lower my amps.
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Strouty
Well-known member
You still are not understanding things, when you run something that was originally a three phase device on single phase via a conversion the amperage rating on the motor has nothing to do with things. If you were to step up to 440, then convert to 3 phase to run that motor, it would not be using "less amperage".
What converter are you buying?
Also I think you are taking all these replies like we are trying to stop you from doing something fun, in reality, people are trying explain things to you so you don't spend an arm and a leg only to realize that you have to spend even more only to find out you still need to spend more.
Not at all. I appreciate all the replies. That's why I'm asking on here before I make anymore purchases.
I did not know that amps change going from 3 phase to single phase source. Know any good resourses as a way to determine how many amperages I would be using on single phase power? The rating of the converter?
It was my original understanding that, with any motor if you run on twice the voltage you can cut amperage in half. Not saying those are the values I would get, but that is part of the advantages of higher voltage motors or so I thought.
Anyways yes I am consulting with an industrial electrician on installing the system in my home shop.
3 phase power is out of the question unfortunately.
Now the phase converter I was looking at, was a 30HP made by North America Phase Converter Company. Model PL-30.
Strouty
Well-known member
That converter requires a minimum of a 70 amp breaker, up to a 150 amp breaker. The 15 HP motor will be on the high end of that spectrum. In other words, you will be using a lot of amperage with large wires. How far is you main panel from the garage?
Strouty
Well-known member
I would talk to the manufacturer and tell them what you have before you buy anything. I would also speak to the electrician first, there may be some other limiting factor to this as well. Money can overcome any issue, but sometimes it just isn't worth it. Luckily, that compressor is most likely normally unloaded, so it keeps the amount of start up amps down. You will definitely dim everything in your house when it starts.
Strouty
Well-known member
That is not terrible, so it won't need oversized wire due to voltage drop. You are still probably going to get sticker shock when the electrician prices it out.
ez-duzit
Well-known member
That won't help the load on your electrical panel at all, as you still need to supply the same watts.
wyliesdiesels
Well-known member
im not digging through the previous 90 or so comments.
What is the HP rating on the compressor?
If more than about 3.5HP, it needs to be hardwired. Unless you spring for expensive pin and sleeve plugs.
Even though your motor only takes 18A on 480V if you use a step up transformer it will take 36A on the 240V side of the transformer. Exactly the same as just wiring the motor for 240V. To produce the same horse power if the voltage is halved then the amps must double. It doesn't matter if you do this at the motor or with a transformer.
If you supply the motor (through a converter or VFD) from a single phase 240V source it will take 1.73 times the amps as it would when running directly from 3 phase. So your motor will take 36A of 3 phase power but the input of the converter will take 62 amps of 1 phase power.
If you supply the motor (through a converter or VFD) from a single phase 240V source it will take 1.73 times the amps as it would when running directly from 3 phase. So your motor will take 36A of 3 phase power but the input of the converter will take 62 amps of 1 phase power.
malibu101
Well-known member
WATTS LAW! Most important for this thread.
OHMS LAW!
MANY OTHER LAWS!
You can't fight physics and win.
Amps and watts are not the same things.
OP- Please keep informed of how this works out.
ez-duzit
Well-known member
You were already advised to buy multiple, smaller, single phase compressors, but you ignored that.
Strouty
Well-known member
You will need multiple compressors, you will NEVER find a single phase compressor that does that CFM.
Find a 90-125 cfm diesel tow setup?
wyliesdiesels
Well-known member
I highly doubt the transformer supplying your service would be able to start a 15-20HP motor and your PoCo may have size limits on HP.
Strouty
Well-known member
It doesn't matter anyways, the compressor he has wouldn't do 60 CFM anyways.
The Quincy QT15 is rated 55CFM @15HP, according to the manual.
Not buy another compressor like you say above, but swap motors on the compressor I would be able to do very easily. However, not something I really want to do if I don't have to.
My electrician was willing to hardwire the compressor for me, so we will see. I ideally would want to run a 3 phase motor on single phase if at all possible. I will find what they can do.
I have about 100 more amps not being used on my breaker.
Not buy another compressor like you say above, but swap motors on the compressor I would be able to do very easily. However, not something I really want to do if I don't have to.
My electrician was willing to hardwire the compressor for me, so we will see. I ideally would want to run a 3 phase motor on single phase if at all possible. I will find what they can do.
I have about 100 more amps not being used on my breaker.
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wyliesdiesels
Well-known member
The amount of power a 15HP single phase motor pulls on startup will be insane for your service.
Do you share a transformer with someone else?
Do you share a transformer with someone else?
Strouty
Well-known member
You can buy a 15 hp single phase motor, but.......
Also, you said you need 60 CFM, 55 is not 60
Also, you said you need 60 CFM, 55 is not 60
You could swap it out for a single phase 15HP motor, but they run $1500+.
You already know about the options to keep the 3 phase motor (rotary phase converter or VFD)
It's not as big of an issue as you think. I know of several grain bin site's that run a couple of 15hp fans on a 200A service. I wired one that had an existing bin with a 10hp fan and they built a new bin with 2x 15hp fans. All runs on a 200A 1 phase service with a 37.5 KVA transformer. Tons of them out there that run at least one 10-15hp fan with a 200A service and a 15 or 25KVA transformer.
Strouty
Well-known member
I had to get the power company to change out my transformer to a larger one, even then, my 10HP single phase compressor dims the lights and I share a transformer with a neighbor, they must love that.
Strouty
Well-known member
Then you need a motor starter......