Lister Engine Forum
How to / DIY => Generators => Topic started by: guest23837 on June 08, 2018, 12:04:27 PM
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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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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.
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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.
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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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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..
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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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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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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
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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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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
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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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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.
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If your loads/equipment are designed to run at 50 hz then set the generator up for 50 hz.
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If your loads/equipment are designed to run at 50 hz then set the generator up for 50 hz.
Everything in the house that I have looked at says either 230, 240 or 220-240 V 50 Hz. I changed the position of the governor spring and the revs are just a whisker over 3000 RPM voltage is 234-235 volts and its a bit less noisy since I slowed it down. I like this generator because it was cheap and 5kv ish its got useful power more than I'd need. Because it has more power than the other generators Id like to connect it to the house via a proper changeover switch.
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Thanks Glort I will take your advice. My other generators are capacitor controlled and if I increase the revs I increase the voltage and Hz even I know this isn't regarded as a good idea.
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I changed the position of the governor spring and the revs are just a whisker over 3000 RPM voltage is 234-235 volts
Sounds like where it should be. You set them to run a little fast at no load and once you add a load it should settle down to where it should be. As you load it up close to maximum you will see it drop a little more. Ideally if it has a good governor you should run about 51 hz no load, be dead on 50 hz about half way loaded up, and it may droop to 49 hz when you get up to full load. Your voltage will do the same thing.
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You have that Funny American power type system, you spin it at 3600.
Don't forget American Samoa, Anguilla, Antigua and Barbuda, Aruba, British Virgin Islands, Bahamas, Belize, Bermuda, Brazil, Canada, Cayman Islands, Colombia, Costa Rica, Cuba, Dominican Republic, Ecuador, El Salvador, Guatemala, Guyana, Haiti, Honduras, Japan, Liberia, Marshall Islands, Mexico, Micronesia, Montserrat, Nicaragua, Palau, Panama, Peru, Philippines, Puerto Rico, Saba, Saint Barthélemy, Saint Kitts and Nevis, Saint Martin, Sint Eustatius, Sint Maarten, Saudi Arabia, South Korea, Suriname, Tahiti, Taiwan, Trinidad & Tobago, Turks and Caicos Islands, United States Virgin Islands, and Venezuela.
;)
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Typically the only things really frequency sensetive are those things that use frequency for timing. Induction motors are one such item so will run at a different RPM with a different frequency applied. This might cause issues if their end load is not prepared for the higher RPM, such as blower impellars not able to accept the added centrifugal force... or the motor at a reduced RPM might not deliver enough torque to maintain the mechanical load and overheat.
With todays global markets, most electronics use switching mode power supplies to make the DC used by the device from AC. As mentioned Most all have become universal and will accept 100 to 250 VAC at just about any frequency, so the plants are not making specific products for specific markets.
If your generator speed is mechanically governed, it will probably vary a little more than 1-2 HZ from no load to full load as mechanical governors MUST droop in RPM in order to increase the throttle as the load increases. My slow speed listeroid runs at a little over 600 RPM with around a 3:1 belt drive ratio which delivers 1800 RPM and 60 hz with a 4 pole generator head. I set it for 62HZ no load and it droops to right around 58HZ at full load. More than acceptable for residential power...
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I changed the position of the governor spring and the revs are just a whisker over 3000 RPM voltage is 234-235 volts
Sounds like where it should be. You set them to run a little fast at no load and once you add a load it should settle down to where it should be. As you load it up close to maximum you will see it drop a little more. Ideally if it has a good governor you should run about 51 hz no load, be dead on 50 hz about half way loaded up, and it may droop to 49 hz when you get up to full load. Your voltage will do the same thing.
I think it's not far away 1% is 30 RPM. I don't think a mechanical governor is going to be extremely accurate. This is holy catholic Ireland so everything thats done officially is done half assed my home generated power may well be better than what the grid sells me. Our power needs would be quite small, 2 or 3 low energy bubs, television, fluorescent light, there is a well pump its 1/2 HP so probably 4 kw left for the oil boiler and fridge.