Onan generator help

[Frantz]

I got a 1971 onan 12.5 generator and dont know where to begin. I was told it was started as a gas motor and started to be converted to propane. I dont know where to begin. I'd like it to run on propane but I've never done anything with propane motors or generators. 100% ignorant! I know it's not a car but yall have some smart brains here. Where do I start here? To prove my ignorance.... I bought it hoping to run machine tools someday and 3 phase seems a smart way to go. Idk if it can do it or even what 12.5 means! Made by Studebaker corp post cars!

[joe_padavano]

Well, for starters we'll need more info on the generator and photos. Is 12.5 the HP of the engine or the kW rating of the generator? How many cylinders? Is it even capable of three phase power?

 

The problem with propane fueled generators is that they are not very fuel efficient and chew through a lot of propane very quickly. If you want three phase power, it's probably more cost effective to get a rotary phase converter to generate three phase from your residential single phase. In fact, depending on the HP needed to run your machine tools, it may be smarter in the long run to just buy a single phase motor for a three phase machine if one exists.

 

Typically you can buy use three phase equipment for a lot less than single phase, with enough of a price difference to pay for the new single phase motor. 7.5 HP is about the largest single phase motor you can get easily. I bought a brand new Leeson 7.5 HP motor for a compressor that I put together. The down side is that for the same HP, a single phase motor requires much higher current than does an equivalent three phase. I had to run a 50 amp circuit for my compressor. That's probably still easier and cheaper than buying a three phase power panel, wiring up the phase converter, and getting all that to work.

 

[Frantz]

12.5 kw.... 4 cylinder.. so maybe 99% ignorant. The three phase interest is cause I see the stuff sell cheap.

[Modeleh]

You’re better off getting a variable frequency drive from Amazon.  I bought one for my 3 phase wheel balancer it was less than $300.  It allows you to use 240v single phase input with 3 phase output of whatever hertz you want thereby allowing you to vary the speed of the motor.  For instance you could have a variable speed drill press or bandsaw motor and not have to mess with belt sheaves for speed changes.  Takes a little knowledge to get it wired up but not too bad. Go on Amazon and search Huanyang VFD.  

I just had an Onan 6.5kw with 201hrs since new short out the windings in my motorhome.  Needless to say I’m not a fan of them. 

Edited August 3, 2019 by Modeleh (see edit history)

[Isaiah]

Onan parts are very pricey also.

[Frank DuVal]

But yours wasn't a 1970 version, was it?😉

 

I also suggest Automation Direct for variable frequency drives.  $138.00 for one horsepower three phase motor on single phase. $320 for 3 horsepower 3 phase on single phase.

[joe_padavano]

7 hours ago, Frank DuVal said:

I also suggest Automation Direct for variable frequency drives.  $138.00 for one horsepower three phase motor on single phase.

 

My point is that you can buy a one HP single phase motor for less than that, and it doesn't require you to incur the cost of the three phase wiring in addition to the phase converter.

[Frantz]

Thanks for the feedback thus far. It's got me researching in the right direction I think. I've done household wiring but really never messed with motors. I'm not in a rush so I figured it's a good time to learn how this all works and add to my tool and knowledge collection.

[joe_padavano]

That's a cool little generator set, and to be honest they appear to be selling in the $500-$1000 range on ebay. It is not a three phase unit, however, only single phase.  Here are a couple of manuals that might be useful. The first is the operating and parts manual and includes info on the propane system. The second covers the electrical parts of the generator unit itself.

 

http://onan.xmsi.net/974-0300 Onan RJC Operator's and Parts Manual (10-1973).pdf

 

http://manuals.chudov.com/onan/Onan-YD-Genend-Manual.pdf

[R Walling]

 I had an Onan that was gas and I converted it to propane.

 It started quicker and ran quieter, but with less power.

 You could convert it back to gas with only a carburetor. When I bought mine, it had a burnt out spot on the armature that would not let it start in that position.

 It was caused by the automatic starting system that tried to start it with a dead battery.

 It was easily soldered and worked well thereafter.

[Frantz]

Thank you for the manual links!!! I paid $150 for it at auction. The auction was for my father in law on the farm I live at and a neighbor had this generator. So I didn't have to transport it anywhere, which adds value too. Neighbor bought it himself as a project he never go around to. Obviously needs some work but didn't seem too bad and motor turns very easy. I've spend more money on worse projects anyhow and learn a little each time.

[Mark Gregory]

I worked on a high-rise apartment building in the early 1970's and they installed a larger version of this Onan Generator and it was very dependable for backup power .

[joe_padavano]

1 hour ago, Frantz said:

I've spend more money on worse projects anyhow and learn a little each time.

 

You're not the only one. 😁

[Frank DuVal]

15 hours ago, joe_padavano said:

My point is that you can buy a one HP single phase motor for less than that

 

You found a 1 horsepower single phase motor for less than $138 new? Even Harbor Freight is more than that!😲

 

Plus a variable speed drive gives you soft starting current and the possibility of varying speed if you want to. The drive gives you motor protection, no need for a "starter" or "overload" for motor protection.

 

Cost of three phase wiring? How much does one conductor cost? You need three plus ground from the drive to the motor, and the same two plus ground (as a single phase motor) from the source to the drive. So, just one piece of wire is costly?

[Digger914]

15 hours ago, Frantz said:

Thank you for the manual links!!! I paid $150 for it at auction. The auction was for my father in law on the farm I live at and a neighbor had this generator. So I didn't have to transport it anywhere, which adds value too. Neighbor bought it himself as a project he never go around to. Obviously needs some work but didn't seem too bad and motor turns very easy. I've spend more money on worse projects anyhow and learn a little each time.

 Great buy on the generator. Try propainecarbs.com the web site is easy to use and they have an 800 number with real people who can answer questions.

[ply33]

39 minutes ago, Frank DuVal said:

Cost of three phase wiring? How much does one conductor cost? You need three plus ground from the drive to the motor, and the same two plus ground (as a single phase motor) from the source to the drive. So, just one piece of wire is costly?

 

Having an extra conductor pulled from the panel to the motor isn't really the problem, the problem is getting the three phase power. Every house I've ever lived in had two phase power into the house. I've only ever seen three phase power in commercial facilities. I guess there are a number of ways to convert from two phase to three phase but those cost money too.

[W_Higgins]

If anyone today has two-phase, you have a rare thing indeed as that system was obsoleted decades ago.  What most people have in their homes in the U.S. is 110v / 220v single-phase.  There are two hot wires, but that does not equal two-phase.

 

Getting three-phase at home usually requires considerable expense if it is even an option at all.  If you have a farm you might be able to pull off a deal with your power company.  You just have to call them and see.  The most practical solution for the home shop machinist is a rotary phase converter:

 

https://www.americanrotary.com/products/view/ar-pro-series

 

In many instances, changing motors on machine tools is not as easy as a simple motor swap because the motor frames are designed specifically for the application, particularly on the better American heavy iron produced from the 1930's and onward.  To further complicate things, on some machines removing the motor involves considerable disassembly to access it.  

 

VFD's have their place, but you really need one for each machine and, if you acquire a lot of machines, it becomes a lot of expense whereas so long as you are only running one or two machines at a time, they can all be fed by the same RPC.  You can even hang a 3-phase breaker panel, use that RPC to feed it, and have a conventional wiring set-up in your shop.  Also, as the horsepower goes up, so does the price of the VFD and, purchasing a lot of them, they can start to get expensive quick.  Another disadvantage is that you need to use the VFD to start the machine, thereby giving up your original machine controls.  You can't fire up the VFD and then use the On/Off switch on your machine.  On some machines giving up the controls is not an issue, but on others it very much can be.

 

I own both and each has it's place, but overall if you want to collect a lot of cheap three-phase heavy iron from auctions and play, a RPC is easy, sturdy, and reliable.  You can probably find a homemade unit for cheap to start out with.  I had one that I used for a long time and later upgraded to a 10 HP unit from the outfit linked to above.  Though today, generally, they recommend a RPC double the horsepower of your largest motor, they used to go a little lower and I run my 7.5 hp lathe with it no problem, but I also don't run it to the extremes of what it is capable in most instances.  Here recently I even got a wireless remote for it and no longer have to go back and forth turning the thing on and off.

  

[chistech]

It seems these days there’s a lot of small amateur machinists selling their stuff and you can find phase converters fairly reasonable on places like craigslist and Facebook marketplace. In most locations, having 3PH power from the street will have an automatic hookup and monthly use fee even before you turn anything on. I have a friend who bought a huge phase converter and powers up his rotary vane air compressor for his body shop. He is still using less electricity (in cost) than if he had installed the 3PH into his building and been paying the utilities fees. Unless you consume a ton of 3PH power, it is not the cheaper way to go. 

 

On the Onan: it’s a good unit and was considered one of the best along with the Winco brand. Most propane units were bought by municipalities to back up things like fire station warning alarms/siren systems and back up pumps. They will still outlast the new Generac units out there.

[Frantz]

I feel my level of ignorance is getting lower. I really had no idea what it was when buying. Read through the manual last night. 120/240 single phase is still ahead of what I have in my shop. I do live on a farm but it's my father in laws so my personal shop is rented off site. The generator gives me the upgrade without affecting the rented property.

[W_Higgins]

So what is it, that your rented building currently has no power at all?

 

Just a point to be aware of since you like dragging home things from auctions -- if you find a 3-phase industrial machine tool that lights your fire, make sure that it isn't wired "440v Only" (primarily with respect to the controls even if the motor is 220v / 440v dual voltage) or else then you're going to be buying transformers or swapping out motor controls.  There is plenty of 220v 3-phase stuff to be had if you are paying attention.  My lathe started life with 440v controls and I've adapted it to make it functional in a regular setting, but it's probably not something you want to get into first starting out. 

 

 

[Frantz]

It has 110 power but it's on a single breaker shared with a little too much. 20x60 w 14' ceilings for $200 a month to work on cars and farm equipment in peace. Plus my brother helps w the rent to store a car there too.

 

I want to get bigger tools like a hot tank and milling machine but my 6hp compressor trips the breaker if the lights are on and the refrigerator in the unit next to mine kicks on.

[Digger914]

9 hours ago, Frantz said:

It has 110 power but it's on a single breaker shared with a little too much. 20x60 w 14' ceilings for $200 a month to work on cars and farm equipment in peace. Plus my brother helps w the rent to store a car there too.

 

I want to get bigger tools like a hot tank and milling machine but my 6hp compressor trips the breaker if the lights are on and the refrigerator in the unit next to mine kicks on.

 

If your generator works you couldn't have done better for where you are and what you say you want to do. I have a 15kva conditioning transformer stuck in a basement closet that would solve your single circuit breaker problem and if I gave it to you, the shipping cost would be more than you paid for your generator. With a single line into your shed a VFD isn't an option and that generator output can be wired up to give you 110, 220 and run your 3 phase machinery which is great advantage to have for the second hand hoist you might want to buy as that expands your options to second hand equipment from some to all auto service centers.

 

Not going to join the discussion on 110, 220, and AC electrical phase as this is a safety thing and mistakes can be deadly. Get an electrician to help you install the power distribution box and at the very least hook up your first couple of circuits.

[Modeleh]

10 hours ago, Frantz said:

It has 110 power but it's on a single breaker shared with a little too much. 20x60 w 14' ceilings for $200 a month to work on cars and farm equipment in peace. Plus my brother helps w the rent to store a car there too.

 

I want to get bigger tools like a hot tank and milling machine but my 6hp compressor trips the breaker if the lights are on and the refrigerator in the unit next to mine kicks on.

 

This thread is making less and less sense.  How are you possibly running a 6hp motor on 110v single circuit? That’s nearly 4500 watts draw. If you plan to run a hot tank off a propane or gas generator it’s going to have to run continually for hours on end it’s going to be expensive and you’re expecting a lot from that old unit.  

[joe_padavano]

1 hour ago, Modeleh said:

 

This thread is making less and less sense.  How are you possibly running a 6hp motor on 110v single circuit? That’s nearly 4500 watts draw. If you plan to run a hot tank off a propane or gas generator it’s going to have to run continually for hours on end it’s going to be expensive and you’re expecting a lot from that old unit.  

 

As you likely know, most compressors are optimistically advertised at stall HP, not continuous running HP. There was even a class action lawsuit about this a while back (surprise...).

 

I have a Chinesium compressor (not my primary one) that is rated at "5HP", despite the fact that it runs on a 110V, 15 amp circuit. Do the math.

[W_Higgins]

1 hour ago, joe_padavano said:

I have a Chinesium compressor (not my primary one) that is rated at "5HP", despite the fact that it runs on a 110V, 15 amp circuit. Do the math.

 

 

To put that into perspective, my commercial Curtis is 5hp, 230v, and 23a.

[joe_padavano]

2 hours ago, W_Higgins said:

 

 

To put that into perspective, my commercial Curtis is 5hp, 230v, and 23a.

 

Exactly. My primary compressor is 7.5 HP, 23 SCFM, and I had to run a 50A 230v circuit.

 

[Frantz]

Yes, it's a cheap craftsman compressor... 6hp is just whats on the sticker.

[Rusty_OToole]

If this is on a farm I would most likely put a stock carburetor on it and run it on ( tax free) tractor gas. Run it when you are working in the shop. For the hot tank I would try a propane burner not electric at all.