hello all
i have a kabota genertor in my bus conversion
when i start it it runs on fasat idle it does not slow down with load change
what is the cause and can it be fixed
thank you
trevor
Gen sets run at a certain RPM to maintain 60 cycles/second. You don't want it to slow down...Cable
What Cable said....sorta. That would be correct if and only IF your gen is asking 120 VAC and doing it at 60 cycles. It should do that all the time and some drop rpm for a moment while they adjust to the load change.
Start you gen WITHOUT A LOAD. Measure the output voltage and verify that you are making 120. If yes, then switch on an AC unit and read the voltage while the load is applied...should be 120 still. Switch in all the AC units and any other load up to the max rating of the gen and verify that the voltage is stable.
Please tell us what model/rating your gen might be. Also, what is the current or watt rating of the load/s.
John
Your Kubota should always run at 1800 rpm.
Your kubota should always run at 1800 rpm, is not really true, not saying your wrong, just not correct, It seems there are a lot of what is referred to as Blackmarket kubotas, they are not really, just a slang the USA kubota dealers use, they are made in england and feature stamford generators. Those will run at 3600 rpm, and don't change much when under a load, i looked for 4 years to find out this info, I had one and loved it. I now have another 5.5 and it runs 2 airs with no problem, finding parts for these is easy if you know where to look, USA kubota dealers are forbidden by their franchise, service ,sell ,parts or repair them, If this is what you have or anyone else out there need parts or info here is the contacts that sell them in the USA, My 5-5 diesel is only 24in by 24 in, generator itsself is side mounted and belt driven, made for boats and tractor trailer units. Purchased from, Next generation power in Jacksonville fl. they assemble them there, and sell parts. There # is 888 463 9879 I hope this helps someone as it drove me nuts for a few years, not that I wasn't already.
Bill 340, I never heard of a Kubota running at 3600 rpm. My Kubota tractor is governed at 2500 rpm maximum. I believe you are thinking of gasoline engine RV generators that might run at 3600 rpm, but for a diesel Kubota that would be a very high rpm. Are these blackmarket engines diesel? Just curious.
Nope diesel, as I stated I have one and one before. Seems to me it is 2800, but some one else told me a while back its either 1800 or 3600 they were made both ways, I know it runs faster than the usa Kubotas, but runs cheap
Many of the small Kubotas run very happily at 3,600rpm. Many should consider the 3,600rpm version since they are smaller, and will still give many thousands of hours of running time before wearing out. They can be silenced easily too. Panda marine generators use 3,600rpm engines that are just about silent when running (in a sound enclosure).
My Mercedes 300 turboDiesel will rev to 5,000rpm, with 4,600rpm being its' normal full throttle shift point. And that's with 381,000 original miles on the engine and transmission (neither have been overhauled yet). My car cruises at 3,400rpm at 75mph. So a high speed Diesel can run a long time. Good Luck, TomC
That is true Tom, but slower lasts even longer, are more fuel efficient, and generally quieter. At least well made ones. I dont think a China diesel falls into that category, lol. Some 1800 rpm Gens have been known to clock over 30,000 hours before having major problems. Thats 3 1/2 years continuous running.
That's true Art, but how many of us will ever come close to 30,000 hours of running time on the generator (if running the generator 4 hours a day-that's over 20 years running everyday)? 3,600rpm gensets are generally smaller, weigh less, and cost less then the 1,800rpm units. With the fuel consumption issue, both just sip Diesel and still consume much less then a gasoline generator. Good Luck, TomC
So continues the myth of 3600 vs 1800 rpm. The quietest generator I've ever seen is a gas, 3600 rpm, liquid cooled Honda.
If an engine is designed for 3600 rpm it is just as efficient, quiet and long lasting as an 1800 rpm one.
;D ;D ;D ;D ;D
Quote from: TomC on April 28, 2011, 11:27:02 PM
My Mercedes 300 turboDiesel will rev to 5,000rpm, with 4,600rpm being its' normal full throttle shift point. And that's with 381,000 original miles on the engine and transmission (neither have been overhauled yet). My car cruises at 3,400rpm at 75mph. So a high speed Diesel can run a long time. Good Luck, TomC
What kind of fuel mileage do you get with the Mercedes? I have been looking at one for my wife.
TOM
All my driving is around L.A., so at times stop and go (for me not very often. Living on the west side and working on the east side [opposite traffic] has its advantages). I average 25 mpg cruising at 75mph most the time (yes I can do that most of the time here in L.A.) or what the traffic is flowing at (which at times during the day can be 90mph). If I slow down to around 60mph, it will go up to 28mpg. Great cars, but repairs are pricey. Mine is an '84 which was the last year of the good ones. Starting in '85 they went to a different turbo setup, lowered the horsepower and went with a 190 model transmission which is to small. There are alot of the 123 chassis running around still, and Mercedes makes most of the parts for them still. Best of all, there are no electronics on the engine or transmission (small electronics for the A/C). Any of the 6 cylinder Diesels (mine is a 5 cylinder) have aluminum heads which won't stand being overheated. As compared to mine being all cast iron. Good Luck, TomC
FWIW>>>> about a nickel,
To set your Gen RPM, a good check is to adj for 60 cycles vs 120 v
just a tip works for me.
I have a 300sd and get about 22.
Back to the Kubota generator. I have a D600 3 cyl. that I am using to make my 7.5 KW generator. It will be belt drive to an 1800 rpm generator head. I will be running it at about 2825 to get the 11 continuous HP that the generator head requires for 7.5 KW. The 2825 RPM also corresponds to about the peak torque of 20.5 Net continuous FT LB.
I should be able to run everything electrical I have and not choke the generator.
On the Mercedes thread I had an 83 300SD that I loved, but to fix the heater controls was going to cost me $900 with used parts! --Then the transmission blew. The body was perfect and had unusual two tone brown leather seats. It got up to 30 mpg on the highway, and was the best riding car I've had to date! Unemployment makes you get rid of the unimportant things. Thankfully I kept the bus!
Steve Toomey
PAbusnut
The speed of the engine is irrelevant, you must spin the generator head (alternator) at the exact speed its designed for. That will generally be 1800 rpm, or 3600 rpm. The reason is that eveything running on AC uses 60 cycles. As the generator turns, the field is cut, either twice, or four times per revolution, depending on the number of poles. Each time the field is cut, the cycle reverses. 2 pole alternators must turn 3600 rpm to make 60 cycles, 4 pole alternators must turn 1800.
From purely an efficiency standpoint, direct drive is the best choice, as belts or gears or chains use power that is simply wasted, are noisy, and require regular maintenence. Obviously, if the engine cannot deliver enough power for the alternators rated output, a reduction ratio will work and you simply spin the engine faster to make up the difference, but you could also build it direct drive and simply derate the generator and protect it with lower amp breakers.
You don't derate the generator head KW's are achieved with HP from the engine you can make a 10 KW from a 8KW head with just a HP change.
RPM changes the cycle a 60 cycle 1800 rpm generator can be change to a 50 cycle by dropping the RPM to 1500 rpm and or a 50 cycle to a 60 cycle by changing to 1800 rpm it's not really a rocket science.
I have watched Bill Harris in VA change 3600 rpm heads to 1800 rpm heads without much problems and time but he is the best in the business when it comes to generators of all sizes I should have paid attention then I would know how to do it lol
good luck
I think you misunderstood what I meant. If he is putting a 10KW head on an engine that cannot deliver enough power to provide the heads full rated load at that rpm, the engine will lose rpm and the head will burn up. By simply stating it is now X KW rated capacity and putting breakers rated just above that capacity, the head will never see its full rated load, and the engine wont ever run out of power. In fact, a head that never sees full load will run cooler and last longer.
I know the speed changes the cycles, I did not know you could change a head from 2 to 4 poles or vice versa, but if possible it would allow the engine to make more power.
I kinda see both points: Heads are most likely created in really big jumps such as "up to 10Kw". Hook that up to a 5KW rated motor and the "system becomes rated for what the engine can do. But there has to be a limit and by simply hooking that 10KW head up to 20KW worth of motor will only get you 10KW and then your breakers/fuses will pop. Fuse it for 20KW and it will melt down with that load. And I think that is the root understanding of you both. Some here might be "cornfussed" and I speak to them.
John
John, your are right with the head jump most of the time 1 head will work for 3 or 4 different KW setting with different hp engines then they jump again
good luck
my 81 300TD wagon avg. 27, 30.25 going down I-5 @ 65mph
Robert