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Strange electrical question

mac

Well-known member
I have a wash that doesn't have three phase power, instead it has a phase converter to supply the automatic. This has worked for four other automatics in the past. My issue with it is the wildly different electrical readings on the three phase motors. There is 240 single phase going into the converter. I get quite different readings coming out. As a result when I read the amp draw on the 10 hp blower motors, I get 14 amps on one leg, around 24 on another, and around 35 on the last one. This is the same on all three motors. Anyone know of a way to get these more balanced out? The tech people for the converter say to install a buck and boost transformer before the converter. The data plate on the motors say it should only draw around 22 amps at full load current. Any ideas on how to get these more inline?
 
We assumed mac you used this into the negotiation price on buying this wash right lol I would spend the money to get it right 3 phase power bill would be alot cheaper less amps. I would think if you dont you will always be fighting this battle. If its not a carwash in the middle of the country that can only get single phase power thats a different story and understanding.
 
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We assumed mac you used this into the negotiation price on buying this wash right lol I would spend the money to get it right 3 phase power bill would be alot cheaper less amps
Wouldn't you then have to change electrical panels inside the building? New motors? New contactors?

I'm no electrician, but I did watch one fix a lamp at the Holiday Inn Express last night. It seems like bringing in 3 phase will have a pretty significant ripple effect.
 
It was a real piece of work. Had maybe 5 owners in past 15 years. This is the fifth auto at the place and all the others used this system. Maybe I’m just getting picky. And yes I got a good deal on it. Great location in booming part of city right in main business district. Starbucks next door(which I really don’t care for but good clients). Getting this close to having the auto done. Then all the other stuff to make it a showplace. Will post pictures when I catch my breath and I can figure out how to do that. Wife brought up the best part. This is the last auto I will ever do, so want to make it perfect. Any others I’ll hire it all out, sit in a lawn chair with a cocktail and just offer suggestions. And this machine kicks butt. Only one in entire state that does tall vans. Life is good.
 
If it is that expensive ($30K) just to get the utility company to bring in 3 phase to the building & no further, I would say to use VFDs & inverter duty motors like some of our laundromat equipment. Just a thought.
 
MJ, for a laundromat I am guessing the biggest motors you have are one hp or less. The blowers here have a total of 30 hp. Because of my location in a busy area, the 3 phase power is maxed out. So for me to get it I have to pay for them to upgrade the entire block. That is just to bring it to my building. I would then need a licensed sparky to replace entire panel and then for me to do equipment upgrades. It adds up quickly. Maybe I should just go solar and be a green business.
 
What is the FLA on the blower motors? If they are spinning at full speed and not exceeding by 10% on any leg, I don't think i would do anything. I'm assuming you have proper overcurrent and overload protection on the motor... I would be more concerned about the phase generator holding up and would probably do what they recommend. Are you using a True RMS meter?
 
It’s like 30K to get it pulled in and around 2K for a transformer.

How long are you planning on keeping the wash? 3 phase will halve your amp draw, on average. Long term, 3ph may be the less expensive option. It all depends on how long the payback is and how long you plan on being there. Not to forget, 3ph motors have a lot longer life expectancy than single phase. Single phase motors have gotten crazy expensive and the warranties are crap. I would push back on the power company. Their grid is not your responsibility.
 
MJ, for a laundromat I am guessing the biggest motors you have are one hp or less. The blowers here have a total of 30 hp. Because of my location in a busy area, the 3 phase power is maxed out. So for me to get it I have to pay for them to upgrade the entire block. That is just to bring it to my building. I would then need a licensed sparky to replace entire panel and then for me to do equipment upgrades. It adds up quickly. Maybe I should just go solar and be a green business.

Mac,

I might be worth it to give the below outfit's tech support a call. They are specifically stating avoiding the need for a 3 phase hookup for over 30 HP motors???

 
Mac,

I might be worth it to give the below outfit's tech support a call. They are specifically stating avoiding the need for a 3 phase hookup for over 30 HP motors???

Looked at their website and don’t see them as a viable solution. Thheir smallest motor is 30hp. I have 3 tenhp motors. This is a real head scratcher. Keeps tripping overloads. Just can not understand why the previous Machines ran on this but mine doesn’t. Fri afternoon late. Time for happy hour and ruminate.
 
It is. You just disconnect the 3 wires and I'm pretty sure the blower won't turn on.:p Trying to see if your results are tied to heavy loading or not. Would definitely need to watch the voltage/current and measure using a true rms meter at the same time to get any meaningful data.
 
It is. You just disconnect the 3 wires and I'm pretty sure the blower won't turn on.:p Trying to see if your results are tied to heavy loading or not. Would definitely need to watch the voltage/current and measure using a true rms meter at the same time to get any meaningful data.
Well the man upstairs must have felt sorry for me. Went in today and the darn thing. Worked. There are timers to stage the starting and all three had same readings (and yes with a true RMS meter). Can’t explain it. As i journey through life I am convinced that there are things that we are simply not meant to understand. So after almost 3 months we are finally opened! Took longer and more money than I thought (sound familiar?) but it’s done right, looks damn good, and turns out a spectacular wash. Pictures at 11.
 
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