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Kubota Z482 - Question Regarding Alternator


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Old 02-06-2018, 08:03:41 PM
Nasr Nasr is offline
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Default Kubota Z482 - Question Regarding Alternator

First let my apologize. I could not find a section dedicated to kubota engines.
If this fits in a different section please feel free to move it


I am building a generator. I have a question

Will i be able to use a 1800 rpm alternator with a 3600 rpm engine?

This engine has a sae 5/6.5 flywheel so it will be direct drive.

Thanks
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Old 02-06-2018, 08:22:15 PM
OEM Volunteer OEM Volunteer is offline
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Default Re: Kubota z482 - question regarding alternator

Others here have talked about marrying 1800 rpm and 3600 rpm components but, have always used pulley set ups.

https://www.smokstak.com/forum/showthread.php?t=121845

I'm not sure 1800/3600 direct drive you're proposing is possible but, the resident smart guys would know best. Maybe they'll chime in.
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Old 02-06-2018, 08:23:05 PM
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Default Re: Kubota z482 - question regarding alternator

As a practical matter, no.

If you turn 1800 rpm 60 Hz alternator at 3600 rpm, you'll get 120 Hz power instead of 60 Hz. There is no way around this.

And if you run your 3600 rpm engine at 1800 rpm, you'll get about half its rated horsepower.
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Old 02-06-2018, 09:34:56 PM
JohnnyC JohnnyC is online now
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Default Re: Kubota z482 - question regarding alternator

I got a stupid question so forgive me if I'm missing something here, but can you govern down the motor from what I assume is a constant 3600 rpm to 1800 rpm? Ok, I'll be quiet now

JohnnyC
New Jersey
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Old 02-06-2018, 10:02:32 PM
pegasuspinto pegasuspinto is offline
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Default Re: Kubota z482 - question regarding alternator

Why would you run a diesel at 3600 RPM? Many modern diesels can do it, but it's going to be loud and that speed is really not good for them

Find a power chart for your engine, and see how many horsepower it can make at 1800 RPM, and you can roughly assume you can get 1 kw per 2 hp.

Diesels have rarely been worth a gearbox and I can't think of any that use one. Generac uses them on spark ignited engines but that's because spark engines aren't happy at 1800 RPM
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Old 02-06-2018, 10:55:10 PM
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Default Re: Kubota z482 - question regarding alternator

Quote:
Originally Posted by JohnnyC View Post
...but can you govern down the motor from what I assume is a constant 3600 rpm to 1800 rpm? ...
Sure - the Z482 engine's good for a tad over 5 kW at 1800 rpm. Factor in the efficiency of the alternator itself, and you'd be at around 4 kW.


Last edited by Jim McIntyre; 02-06-2018 at 11:37:49 PM.
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Old 02-06-2018, 11:26:16 PM
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Default Re: Kubota z482 - question regarding alternator

That chart makes it appear you can get to 3600, but that is red line. Don't expect the engine to last long there.
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Old 02-06-2018, 11:27:39 PM
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Default Re: Kubota z482 - question regarding alternator

You should be able to get a 2 pole 3600 RPM alternator with the correct SAE coupling disc to bolt up. Or use some sort of cogbelt 2-1 drive setup . Seems easier to change the engine or alternator to something that just fits though. Cheers Dan
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Old 02-06-2018, 11:32:58 PM
Birken Vogt Birken Vogt is offline
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Default Re: Kubota z482 - question regarding alternator

I have a customer with a factory MQ generator running at 3600 RPM. I'll let you know in a year or two how it does. I have been told over and over that these smaller diesels are fine at 3600 but I will not sell one to anybody.

Edit: to be clear the MQ is also a Z482 so we shall see.

Last edited by Birken Vogt; 02-07-2018 at 12:14:16 AM.
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Old 02-07-2018, 12:09:53 AM
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Default Re: Kubota z482 - Question Regarding Alternator

Maybe a small set in 'light duty' standby would be OK. I want to see a 16v71 scream up to 3600! I am pretty sure the sound waves would open up microfissures in the fabric of space.
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