Author Topic: Engine speed and Hz  (Read 1346 times)

Johndoh

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Engine speed and Hz
« on: June 08, 2018, 12:04:27 PM »
I can't find an answer searching this site but I imagine this is an easy one for you guys!

I was playing with my new toy earlier and I decided to check the RPM it was almost 3600. Generator is producing about 230v =/- 2 volts. I slowed the engine down to 3050 RPM voltage stayed the same. Is this the correct thing to do? I only loaded it with hair dryers grinder etc nothing sensitive when I was testing it. I don't want to blow up the TV etc when I actually need to use it. My question is are some generators 3600 RPM and still 115/240 volt @ 50Hz? If not would it ruin the AVR over time?

Thanks
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broncodriver99

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Re: Engine speed and Hz
« Reply #1 on: June 08, 2018, 01:01:56 PM »
A 2 pole generator would operate at 3000 rpm for 50 hz and 3600 rpm for 60 hz. A 4 pole generator operates at 1500 rpm for 50 hz and 1800 rpm for 60 hz. I believe most modern generator heads are fine at either frequency.

glort

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Re: Engine speed and Hz
« Reply #2 on: June 08, 2018, 02:43:36 PM »

Most important thing is to get the frequency as close as you can. AVR will take care of voltage and if it does not, it's not that important anyway BUT, it can't adjust frequency.  Put about a half load on the thing and adjust the engine speed with the governor screw till you get it to the correct Frequency ( 50hz) as close as possible.

Many generators are off when you get them and will wander over time as the wear. It is good to check them every so often.  I used to use one in varying conditions and pretty much checked it every time out. Wasn't hard and it was surprising how much it moved from being down in a valley in the middle of winter to out the dry country in a heat wave.

Even fuel can cause shifts.

Most of the attached type Generators that are all in ones will be the 3xxx speed ones.

38ac

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Re: Engine speed and Hz
« Reply #3 on: June 08, 2018, 02:53:30 PM »
I dont know what the new toy is but the short answer is no. For almost any usage an A-C generator needs to run at the proper RPM so the hertz  is correct.

 Long answer,  With A-C current two things are important for most loads, frequency and voltage. When you slowed the shaft speed own you changed the frequency or hertz which screws up any motor load you put on it and possibly electronics. Light bulbs and resistance heaters dont care,  The AVR is doing what it is supposed to do, keep the voltage at up, will it damage it over time? Possibly.

 If your desires are for a slower running engine you to change the  drive ratio if belt driven, this allows you to slow the engine down but keep the generator at proper RPM  If  direct coupled your stuck at 3600 RPM for 60 hrtz.  You set it just above 60 with no load and under fullload it will drop to 58-59 with most set ups.
Collector and horder of about anything diesel

Johndoh

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Re: Engine speed and Hz
« Reply #4 on: June 08, 2018, 02:55:15 PM »
Thanks guys for once I was on the right track I will load her up later and set the RPM. A little side effect is that it's a bit quieter so result!
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Johndoh

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Re: Engine speed and Hz
« Reply #5 on: June 08, 2018, 03:00:40 PM »
I dont know what the new toy is but the short answer is no. For almost any usage an A-C generator needs to run at the proper RPM so the hertz  is correct.

 Long answer,  With A-C current two things are important for most loads, frequency and voltage. When you slowed the shaft speed own you changed the frequency or hertz which screws up any motor load you put on it and possibly electronics. Light bulbs and resistance heaters dont care,  The AVR is doing what it is supposed to do, keep the voltage at up, will it damage it over time? Possibly.

 If your desires are for a slower running engine you to change the  drive ratio if belt driven, this allows you to slow the engine down but keep the generator at proper RPM  If  direct coupled your stuck at 3600 RPM for 60 hrtz.  You set it just above 60 with no load and under fullload it will drop to 58-59 with most set ups.

The new toy is a single cylinder diesel generator 5kv. The machine was bought used partially assembled with bits of it in bags and boxes. It's directly connected no belts. Obviously someone had been playing with it prior to me getting it. he couldn't get it to start. It had an electric fuel cut of solenoid I took the plunger out and bled it worked ok. In Ireland power is 230 v ac 50 Hz usually 3000 RPM I was thinking he had maybe adjusted it in the hope of getting diesel to the injector. I'm getting confused a little now..
« Last Edit: June 08, 2018, 03:16:51 PM by Johndoh »
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glort

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Re: Engine speed and Hz
« Reply #6 on: June 08, 2018, 03:27:51 PM »

Damned China engines.

Mate Pops over yesterday and Says we nearly owned half an excavator each.  Found this little baby one that would have been perfect for me especially.
Had all the buckets and accessories and was cheap as Chips.  I says why didn't you buy the bastard? He says I started it up and the engine had a Knock. Turned it off and sounded like it was going to explode.  I said what sort of an engine? Pulls out his phone and it's Yanmar vertical type.
He says those things can cost $1200!

I said yeah, and I have 3 Never used ones up the back now and I have another 3 that I have been playing with up there too.
I said ring up and buy the thing . He says too late, went to auction and was sold yesterday.

BUGGER!

Johndoh

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Re: Engine speed and Hz
« Reply #7 on: June 08, 2018, 04:30:57 PM »
They are noisy buggers for sure but fairly reliable and easy run. There's quite a lot of them Yanmars and the Chinese ones put into motorbikes
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Johndoh

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Re: Engine speed and Hz
« Reply #8 on: June 08, 2018, 09:20:31 PM »
I read the manual for the engine and 3000 RPM is correct for 50Hz. I have added a photo of the page. Glort nearest I can get is 3011 RPM I reckon thats close enough?

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EdDee

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Re: Engine speed and Hz
« Reply #9 on: June 08, 2018, 10:55:35 PM »
Here a cat among the pigeons...

On my units, I tend to set at around 60hz or 3600 for the short run stuff like portable units and emergency, lets get the lights on so we can start the big gennie  type units... at the higher rpm, smaller gens get  better cooling to the genhead, better able to handle surge loads, correspondingly they are able to provide 20% more power too with no real ill effect...  Lets face it, they were designed for 60 as well as 50 hz... All my electrical appliances and goodies have shown no damage over the years from this either.... Its the very low frequency 60 million volt sparks that seem to wipe out my stuff....

Cheers
Ed
12/1 750RPM/9HP Roid 5kVA- WMO Disposal/Electricity & Hot Water Gen
12/1 650RPM/8HP Roid 4.5kVa - Demon Dino
Chinese Yanmar - Silent Runner with AutoStart
Classic Komatsu 1963 Dozer/Fergusson 35 Gold Belly ...
Bikes,Cars,Gunsmithing & Paintball...Oh yes, a 5Ha open air Workshop to play in!

Johndoh

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Re: Engine speed and Hz
« Reply #10 on: June 08, 2018, 11:19:33 PM »
Here a cat among the pigeons...

On my units, I tend to set at around 60hz or 3600 for the short run stuff like portable units and emergency, lets get the lights on so we can start the big gennie  type units... at the higher rpm, smaller gens get  better cooling to the genhead, better able to handle surge loads, correspondingly they are able to provide 20% more power too with no real ill effect...  Lets face it, they were designed for 60 as well as 50 hz... All my electrical appliances and goodies have shown no damage over the years from this either.... Its the very low frequency 60 million volt sparks that seem to wipe out my stuff....

Cheers
Ed

I know that it will run lights etc but TV modem computers etc might not like the 60 Hz?
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EdDee

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Re: Engine speed and Hz
« Reply #11 on: June 08, 2018, 11:37:13 PM »
Hi JD

They don't mind it in the least.... switch mode power supplies in pretty much all of them... most you can even run straight off 110-220v dc even....

an old wall clock with an electric motor in or an old record player with similar would run fast....

Ed
12/1 750RPM/9HP Roid 5kVA- WMO Disposal/Electricity & Hot Water Gen
12/1 650RPM/8HP Roid 4.5kVa - Demon Dino
Chinese Yanmar - Silent Runner with AutoStart
Classic Komatsu 1963 Dozer/Fergusson 35 Gold Belly ...
Bikes,Cars,Gunsmithing & Paintball...Oh yes, a 5Ha open air Workshop to play in!

Johndoh

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Re: Engine speed and Hz
« Reply #12 on: June 08, 2018, 11:57:38 PM »
So the generator might have been designed to run at 3600 rpm and 60 Hz? This is confusing me because I read somewhere that Hz shouldn't vary by more than 1-2 Hz under load compared to idle. The generator used to be an enclosed silent unit so maybe thats why it was higher speed? Cooling? It's now open with a standard type exhaust blowing out the side so Im thinking it must run cooler. Should I go back to 3600 RPM?
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broncodriver99

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Re: Engine speed and Hz
« Reply #13 on: June 09, 2018, 12:05:56 AM »
It depends what market it was designed for. Here in North America everything is 60 HZ. A lot or most of the rest of the world is 50 HZ. A lot of stuff is designed to run either way and most generators will produce either depending on what RPM they are set for.

broncodriver99

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Re: Engine speed and Hz
« Reply #14 on: June 09, 2018, 12:11:41 AM »
If your loads/equipment are designed to run at 50 hz then set the generator up for 50 hz.