I'm looking for a propane generator around the 60KW range. The only company I can find that makes one is Kohler. Anyone know of any other options? I'm located in the MI, IN, OH tri-state area. Thanks.

Edit: CAT and Generac also make them. I guess they're a new offering from CAT.

Check out "Generator Joe" web site (www.generatorjoe.net). Their equipment is mostly industrial and very reasonably priced.

Any natural gas generator can be converted to liquified propane. The company that sells it just has to sell you a kit to do it. You found 3 of them. Also there's Onan, Cummins, Perkins (same as CAT in reality), and probably several others. Another name that comes highly recommended but isn't as common in the Midwest is Katolight. They are made in Minnesota.

Regardless of the source, generally the folks making generators are either motor/generator shops that buy engines from someone else or engine shops that buy the generators from someone else. About the only exception is CAT who is buying Perkins engines and attaching a generator from someone else as well, sold under the "Olympia" name.

If this isn't going to be permanent mount though, here's a dirty little secret about generators in general. Most decent industrial duty welders have generators built in. Quite often at least at the low end, welders are actually less expensive than generators, even if you never, ever use it to stick two pieces of metal together. That's at least the case up to about 20-30 kw, not sure about the range you are asking for.

In addition, at the size you are talking about, you will probably find that even though diesel generators are a pain in the rear to maintain relative to a gas one, the cost and reliability will probably be better simply because you have the advantage of much higher achievable compression ratios.

I haven't bought a 60 kW generator before but I have bracketed you...I've bought 10's and 20's as well as a 300, and the above is roughly speaking, what I've learned over time. The 20-40 kW range is somewhat unusual in that it's the break point between the "industrial" and "commercial/residential/construction" size range. Right in that range, you can get quotes from both markets. The industrial stuff is much more expensive but built more for reliability. In the size range you are asking for, it will probably all be industrial-duty unless you can find a large "welder" type unit meant to support multiple welders pulling off the same unit such as running steel columns/beams for a construction site where they use continuously fed wire welding and guys weld in pairs to prevent warping.

I think you will find that nearly all 60Kw engine gen sets will have a diesel driver. I have seen a couple large gasoline type engines but they were adapted to natural gas.
Cat Cummins are good resources - look in yellow pages you will not find many dealers for this size unit - the smaller size shops will steer you to the guys who have what you need - probably the larger diesel shops who will sell and maintain.

I believe diesel is much simpler to maintain than gas. They are also much more reliable and more efficient. The main downside is cost but you get what you pay for.

I would not use a welder generator solely as a stationary generator. The reason is that you are not able to load the engine and run it too cool and carbon up the injectors. Run a diesel at 80 % load on the average for best performance and least maintenance.

Dan Bentler

Check out this thread on Eng-Tips for comments on propane fueled generators

http://www.eng-tips.com/viewthread.cfm?qid=240774

Dan

Thanks for the tips guys.

It's going to be propane because at the location, that is the most readily available fuel, and they want an on-site tank.

It's backup power for a utility, so it will definitely be industrial grade.

Not exactly apples to apples but "on the farm" our 35kw peak / 20kw continuous 240 single phase generator needed a 60 HP minimum deisel tractor to run it and our 90 hp tractor turning at 1750rpm worked just great. You mention 60 kw I assume that's continuoius and you need 95 kw peak and probably a 225 hp motor just swag here.

http://www.generatorjoe.net/SpecSheet.asp?ID=2195

Spec sheet for a 80kW Kohler 480VAC genset running on propane uses a GM 496 cubic inch engine producing 150 HP. The 60 kW model only produces 54 kW continuous so I had to bump it up to the next size.

http://www.generatorjoe.net/SpecSheet.asp?ID=2198

The next size up nets you 100 kW peak. Not sure where the "95 kW peak" number came from. Engine is the exact same size though.

One thing to watch out for with generators is peak power. If you have motors that you intend on starting while the generator is running, the startup current (usually assumed 6 x FLA but can be as high as 21 x FLA with some energy efficient motors) is VERY important and drives your generator specs. I missed that once and had all kinds of startup issues with a 200 HP motor stalling out the generator that it was connected to. When I put in the large generator I mentioned in a previous post, I also bought several soft starts for the 75 HP motors that it was running. This allowed me to size the generator for the maximum load plus only 50% of the 75 HP load (using the soft start to current limit to 150% of FLA). Without the soft starts, the generator spec called for 600 kW. With the soft starts, it went down to around 250-300 kW. If you go this route, also pay close attention to the pricing on drives. Quite often these days there are funny things that happen where a drive is often less expensive than a soft start, and electronics are cheaper than the old delta-wye stuff, or wound rotor motors.

Paul the 95 KW peak was a swag since the 20kw cont was 35kw pk, having at least 35 kw of peak capacity seemed reasonable to be. Just good ole hillbilly farmer swag.

Your comments about motor sizing and starting also ring very true.

When on generator we could start all three vacuum pumps in the barn or the silo unloader and two pumps but not all four motors. Of course back then we didn't understand FLA and starting inrush like I would calculate now.

They get more power out of the same motor by adding a larger alternator.

Most companies now have sizing software, so that takes a lot of the design burden off the engineer. I sized this one with Kohler's online software.

Some people still prefer soft starts over VFD's because they see a benefit of reliability in the hardware, if there is no reason to do speed control. Then again, we've had clients add VFD's then add soft starts on a VFD bypass. In water utility, they're a bit slow getting into technology, and reliability being of utmost importance, they get nervous adding a computer in the mix that they can' just have their maintenance replace quickly.

slightly off topic here Jon, but we are seeing a lot of energy savings using VFD's for pumping and establishing flow and pressure targets and ramping the VFD to meet these targets. With the push on "green initiatives" this can be a useful bit of knowledge.