single to 3 phase converter - on a truck

[slowwilly]

I have a customer who purchased a 3 phase compressor. 16Amp running load. Unfortunately, he has only single phase power avaliable.

I'm looking for a phase converter, but the trick is, this compressor (and converter) are on the exterior of a delivery truck. So, it will see vibration and rain, sand, etc. No road salt, as the customer is in Miami, Fl.

Do you know of any converters that are vibration/environmental qualified for over the road use? How heavy/expensive will the congerter be?

For reference, he can get the motor/compressor changed to single phase for about $2400, with a small overall weight impact.

Thanks.

 

[itsmoked]

If you are talking 240V(not specified) you are talking a 5HP motor. Finding anything(inverter/converter) that draws 5HP single phase power is not easy. Finding same that can run(and worse start) a 3 phase compressor will be harder yet. Compressors are tough starting devices(very).

Let me suggest something else. Why not ditch the motor all together and use the transmission power take-off to run a hydraulic pump. Then run the compressor with a 'tiny' hydraulic motor. Ditch the electrical motor all together. Use the 200HP under the hood that already exists and has been paid for.

Otherwise pay the $2,400...

Keith Cress
Flamin Systems, Inc.-

http://www.flaminsystems.com

 

[BJC]

"customer who purchased a 3 phase compressor"
Usually in this form the above means he found one cheap or otherwise came into the compressor for next to nothing and then finds out he has to spend some serious bucks to make it work and even so it ain't going to work.
If your serious about putting tools on truck get one of the combination welder, generator compressors that pipelines use. I think Miller and Hobart make them.
Most of them use diesel engines and very durable. People who use them to make a living don't screw around jury rigging bargin junk.

 

[jraef]

AC Tech makes a 5HP VFD that can accept a 1 phase input and give you a 3 phase output without derating (SCF Series only). I know you don't need variable speed, but you just leave the output speed at 60Hz. I also beleive ou can get it in a NEMA 4X (hose-down water tight) stainless steel enclosure as well. Not sure about "over-the-road" however. I have put lots of VFDs on mobile equipment but the long term survival rate is less than stellar to be honest, but then again most electrical equipment is not designed for that anyway, so as the saying goes, "ya pays yer money and ya takes yer chances". Wouldn't hurt to ask them about that issue though.

Eng-Tips: Help for your job, not for your homework Read faq731-376

 

[MikeHalloran]

If he's compressing air, he could probably find a nice air compressor intended for powering the brakes of a larger truck, already set up for use on a vehicle.



Mike Halloran
Pembroke Pines, FL, USA

 

[slowwilly]

I guess I should have stated: this is a refrigeration compressor. There was no real cost difference, the customer simply didn't know what he was doing when he ordered the system.

The compressor does not run when the truck engine is running, only gets plugged in overnight.

I had done a quick online search & found plenty of phase converters that seemed to electrically do the trick. A few in NEMA 3R & up enclosures. But none say that they are vibration qualified & none listed the weights.

Sounds like it may be a lost cause & the right thing for him to do is change the compressor.

 

[ScottyUK]

If it is only plugged in overnight, why mount the converter on the truck? Is it parked at a different location each night?


----------------------------------

I don't suffer from insanity. I enjoy it...

 

[slowwilly]

"Is it parked at a different location each night?" Per the customer, yes & they're all single phase locations.

 

[rbulsara]

slowwilly:

you may have bigger issue than that. Single phase equivalent of 3 ph, 16A would draw in the rage of 50A to 60A. Single phase units have even poorer power factor. Starting duty may require at least a 70A breaker??

What voltage are we talking about here? What is the application? You may find it hard to get a 60A or 70A single phase feed/breaker at every location.

 

[BJC]

"Sounds like it may be a lost cause & the right thing for him to do is change the compressor."
Might be best to look for smarter clients. Whats this guy doing delivering meat, fish of something of the sort? Even if he gets a single phase motor and can't plug in one night what happens?
As an engineer once you "touch" this jury rigged outfit you own it and your one of the people the lawyers put on the list. If you read in the paper that a number of people have gotten ill after eating at a restaurant this guy delivers to it's time to move.
Truck cooler come in sizes to fit vans all the way to 40' trailers.
Ignorant clients are risky for engineers to deal with.

 

[jraef]

Good point rbulsara,
Although he didn't share his voltage, I'd assume that anyone trying to run 5HP at 115V from a portable cord would be insane. ;-)
I assumed 230V, so around 28A. That still implies at least a 30A circuit, better off with 40A, either of which is going to be really difficult to find anywhere.

Slowwilly,
So if these are established "route" locations where they will be installing a special circuit to feed these things anyway, then ScottyUK's point becomes very valid. Put the inverter at the site, don't carry it on the truck. A side benefit to that will be that the lower 3 phase current means smaller lighter cable. If you have to run portable cord to a 40 A circuit on the truck, it will need to be at least #8-3 conductor type SO cord, about 3/4" thick and very heavy.

If on the other hand the locations are random, then as others have said you've got a bigger problem at hand, even if you do change the compressor motor to 1 phase.

Eng-Tips: Help for your job, not for your homework Read faq731-376

 

[itsmoked]

I cannot think of a fresh food distributor that would park his trucks 'just here and there'. I have always seen them park the trucks at not only the same address but usually in 'the trucks' specific parking place. This is standard for cold plate trucks!

I would re-check that.

I would also commend your customer for his brilliance in shifting to 3phase from the much more problematic single phase systems. I would help him convert one parking spot to three phase and then make a point of parking that truck there! Then just proceed with his business while "testing a 3 phase system". He will soon discover that the 3Ph system lasts 50% longer than the 1ph ones. The wire is smaller, the cord probably lighter, and the plug perhaps, less expensive.

Keith Cress
Flamin Systems, Inc.-

http://www.flaminsystems.com

 

[jraef]

I've seen it done itsmoked.
Meat delivery trailers, dropped off at night and not unloaded until the next day by the early crew.

Eng-Tips: Help for your job, not for your homework Read faq731-376

 

[itsmoked]

Can you tell me specifically where a truck looaded with meat is parked tonight??


You should not have seen it done since you cannot, to my knowledge, leave a "cold plate" truck 'unplugged in' overnight. Cold plate trucks are usually only useful for delivery never storage. They also don't gennerally cool anything down they can only replace heat leakage into a box.

Anyway that's my experence working as a meat truck driver all over Oakland, San Fransico, San Jose, Santa Cruz mountains and Santa Cruz. A fully refered truck sure!

Keith Cress
Flamin Systems, Inc.-

http://www.flaminsystems.com

 

[CLAYSELEC]

Kidey of reminds me of those Swan food guys. they sell frozen high dollar food directly to retail customers and have routs. The plug up at hotels were they stay. many years ago I worked at one and we had special power set up along a fence for about 8 trucks It sounds as though he may also need to plug in at hotels, though a hotel without 120/208 3ph would be realy odd. Perhaps they don't want to deal with the cost of a custom install or he may not always stay at the same place and may only arange to use the A/C recpt in another room, which is usualy only 208v 20amps, not enough for 5 hp. refig comp .At 208v it will need a 60 amp ciruit to ensure you don't get nusance tripping. He definatly doesn't want to trip a breaker while he's asleep!

 

[itsmoked]

Yep! Reminds me of the time a refrigerated rail car left Castroville,CA (Artichoke Capital of the World) packed with Artichokes. It went across country though Texas to New Jersey where it was found that the cooling had failed. It was then returned back to Watsonville, but not before being sided in Texas for a week. I was working on a REMAT^TM Fuel Saver product development standing in the Watsonville yard when the car returned.

It was quite amazing. The car was actually bulging slightly. It looked wavy from the heat radiating off of it. They had to use a fork lift to batter the door open. When they got it open we all stood transfixed as steaming black goo the consistency of wet bread dough oozed out like extra viscous lava. Nice smell too.

Very memorable.

Failed refrigeration = a bad thing

Keith Cress
Flamin Systems, Inc.-

http://www.flaminsystems.com