So.....

I would like to build a 30Kw generator. I have a nice little 2.2 litre (135ci) 4 cylinder diesel out of an '84 mazda pickup (metric perkins 4-135) with only 200,000 Km on the clock.

For the life of me I can't seem to google connection methods between the crank shaft and the alternator. (alternator being the part that produces the 30Kw of electricity)

I can't see it being any kind of a solid connection. I can picture something like a steering rag joint only more robust.

Any ideas? any other tips or pictures...?

I don't have the alternator yet. I would like to find one that runs at 1800 rpm for noise, fuel consumption, and wear on the engine.

 

I believe they are called Drive line isolators. How much power does that motor make, I bet you could use some from like a John Deere fairway mower

 

Advertised horsepower is 59HP @ 4000 rpm I would expect it to be less at 1800 rpm.

....... then again, if it's much less I might not have enough to spin the alternator at rated power (I doubt the house would draw that much if I had everything on anyway.....)

 

If you are thinking of making a direct 1:1 connection to the alternator than I suppose you would need to know at what RPM the alternator would produce your 30KW?

Lots of 5kw generators have 10h.p+ engines so by that logic 30KW would require 60 HP?

That is just a broad assumption I just made in my head, perhaps a 30KW alternator is more effecient than the type used on contractor model gnerators and such, I'm not sure.

Neat project though, very interesting.

What are you planning on running that requires 30KW?

 

A general rule of thumb with generators is that it takes roughly 2 HP to make 1 kW.

I like your project. I have always wanted to build my own set too, with a 3.9 Cummins.

 

You could put a manual transmission behind the engine (This would allow correct RPM / Torque ratio) then run a drive line to the gen set..be sure to use a slip yoke to allow for movement and cut down on vibration.

 

westcoaster,

That sounds like a fun project and your hp matches your proposed KW nicely. Like jrs said, about two HP per KW. But your engine will need that much power at 1800 RPM. Does it have it? If not you could just derate the genny a bit. Another issue is a governor to keep the speed correct at various loads. How will yo do this?

There are a number of industrial couplngs that will work where the two shafts point at each other and are closely aligned. One has a sproket on each shaft and a piece of duplex chain ties them together. Another uses a trapped rubber piece that transfers the torque. Another uses a star shaped piece of plastic that rides in a matching star shaped hole in each shaft connector. This is all industrial or farm technology. Whatever you do do not directly couple the two shafts with a rigid connector! If you have some room a driveline would also work. One with two U joints to allow for misalignment. A belt drive will probably not work because automotive engines don't seem to like full power being drawn from belts and all the side load it puts on the crank. The bearings are not good enough for that.

A couple of gennys that I built used generators that could turn either way so rotation was not a problem.

 

I did think of that. I pulled the engine and tranny in one piece, complete two piece drive shaft with center bearing, complete exhaust system, fuel/water seperator from the frame rail under the fuel door, the fuel filter housing with manual priming pump, rad and hoses, air filter assembly, and complete one piece engine wiring harness. I cut the truck harness so I wouldn't disturb the engine harness....

The only problem with keeping the tranny attached and using a drive shaft is length. If I used a drive line isolator as suggested above, my overall length would be around 7 or so feet. The tranny by itself (counting bellhousing) is around 4 feet (give or take). It's actually quite long!
Adding the tranny in I would be lucky if I had this thing built under 15 feet. That wouldn't be an issue if I had 7 acres of land. All I have is a city lot.....

edit:

5th gear on the tranny is shot. I would guess the rest is on it's way out as well....

 

A tranny would make the whole thing bigger and it would rob some power. Much cleaner to direct drive it.

John

 

If you just have a city lot you are only planning on running your home in situations where you need backup power???

Wow, 30KW is MAJOR overkill for that type of application.

How much does a 30KW alternator cost?

 

no idea.... Any suggestions?


This is probably the only thing I know about this project.....

 

No idea on the governor but it could be a deal breaker. Accurate RPM is essential.

 

lovjoy coupler like used for hydrolic pumps and other things and a lock set throttle

 

~$1000

Fleabay
http://cgi.ebay.ca/30KW-ST-Generator...QQcmdZViewItem

Come to think of it, 30Kw is a little big.......

But then again, I'll be the only guy on the block with all the lights on, dishwasher, electric dryer, furnace,sterio and TV going full boar AND I'll be out in the garage welding pieces of scrap steel together just because I CAN!


I may need to re think this, my neighbours think I'm strange enough as it is....

 

If the bell is an SAE size you can get a generator end to bolt up. I am in the process of building one with a thermo king 2.2di engine. Most of the generator ends are advertised overrated. They like to advertise the surge power of 30kw which will really give you around 21kw or so. Better to have a larger generator than the engine will use so that if you overload it there are not electrical problems from it.

You will be looking for a dedicated 110/220 end that has four poles. That is 1800 rpm. If you use a three phase end wired for 110/220 you lose about 1/3 of the capability.

As you said, getting the governor right will be your challange. An industral engine has a rock solid governor. You can get thermo king engines at a nice low price. About 40hp is ideal for what you want and they get outstanding economy.

I have a Marathon 21kw end that surges to 30.