Lister Engine Forum
How to / DIY => Generators => Topic started by: Jackie on January 02, 2019, 05:28:00 AM
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Generator drops volt from 220 50Hz to 180v 50Hz with 2.4kw heater element load It seems governor does not increase speedon heavy load. Please help As we have a huge drought in South Africa and i need genset to pump water
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Hi Jackie and welcome. There are a lot of reasons why this might happen but before anyone here can start to form a diagnosis we need to know what type of generator it is. Make and model of both the engine and the generator head please. Photos will help with identification if it is unbranded.
Posting photos is easy, just below the square box that you type in there is a line that says: Attachment and other options. Click on this and you should be able to post up to four pictures.
Good luck
Bob
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Hi
Thx guys i tried posting photos but size is problem I am goin to take new ones less pixels snd post them shortly
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Hi Jackie, some modern cameras have too great a resolution to send easily. looking forward to seeing what you have got.
Bob
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Hi guys aatached the genset info Thx
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Attached the ST2 engine plate
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Sorry wrong pdf
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Hi Jackie, thank you for the photos of the plates, we now have some idea of what we are dealing with. You have a Lister ST2 diesel engine coupled to a Hoffberg generator head. First observation is that you have a 10 KVA head coupled to diesel engine that maxes out at around 8 KVA. Don`t panic that is a good thing. Much better to stall a diesel engine than to burn out a genny head.
You say in your first post that the output drops from 220 volts at 50 Hz to 180 volts at 50 Hz, is that actually right? This is a drop of around 20% so what I want to know is if it is pumping out 180 volts at 50 Hz or 180 volts at closer to 45 Hz. Put more simply is the engine bogging down under load or is the generator head not producing what it is expected to?
Once we have sorted out where the problem lies we can probably get a diagnosis pretty quickly and talk you through trying to fix it.
For what it`s worth, with the information available, I am thinking the problem lies somewhere in the diesel engine fuel system.
Bob
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Hi
Yes the frequency did drop as well and I increased the engine revs back to 220v while load was on So it seems I have a governor problem as the engine took the higher revs and still had to got What should I check ? Maybe givernor etc. Thx for advice so long
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First thing, if you've not already done so, change the fuel filter and check the condition of the fuel - water, rust, dust ect.
If there is any doubt cut open the old fuel filter and check how much crap is in there.
I can't download all of your photo's, but if there's an air filter, clean that too.
I know it all sounds basic but eradicating (a two dollar word there!) the obvious and easy is generally a good idea.
Cheers
Stef
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Thx Steff
I have changed diesel filter - clean diesel - i will try and remove air filter as i could not get new one although it looks clean
Could it not be governor mal funtion as i can manually bring engine up to speed?
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Hi
Something worth to mention is the diesel is gravity fed Should that be presurised or not? About a foot above engine head.
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Hi Jackie, very unlikely to have anything to do with the height of the fuel tank unless you have altered it recently. It is also very unlikely to be the governor mechanism as it is very robust and good for many thousands of hours.
I, like Stef, think it is a good idea to start with the simple and obvious and work up. If you can`t change the air filter, remove it all together and see if that improves things. (Please don`t do this in a dust storm).
It is interested that you can bring the engine back up to 1500 RPM manually. This to me suggests that the governor may not be operating the racks on the fuel pumps as quickly as it should or that you have some dirt in the fuel injector nozzles, either one of which will reduce engine HP, this would normally be compensated for by the governor opening the racks on the fuel injector pumps further. Did this problem come on suddenly or has it been a gradual thing over a period of months?
Does the engine produce a lot of blue, black or white smoke at any point while running?
Bob
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Hi Bob
Ok the genset has not run for about three years. When I push the govenor rack on injectors I do get some black smoke but not much. I do not know if it did this before as i just bought it No white or blue smoke
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Hi Jackie, I think you have a generator that will probably last you for years, it hasn`t been run for 3 years and is a little weary from neglect. Do you have access to a bottle of diesel fuel system cleaner? If you do pour some in the fuel tank, run the engine up and hen leave it over night to dissolve sh1t in the fuel system.
Failing that we shall have a play with the injector rack which may have some corrosion on it (please see photo)
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Hi,
Thx for info The fuel rack is exactly like mine I will get some fuel system cleaner but I do not have any rust or anything dirty in this rack area but yes inside might be dirty
Let me check it out!!
Jackie
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As it looks like a governor problem you could try........
Disconnect everything except the water pump, start the genny and then use a bit of string, baling wire or bootlace to manually get the revs into the correct zone and stay there.
As it's a constant load it should stay wherever you leave it, with a bit of luck whatever is stuck could well free up with the warmth and vibration, should you be that lucky the motor shouldn't overspeed, the governor ought to shut it down.
Anyway, if you stand by it for half an hour or so you'll have moved some water in the right direction whilst Bob continues with the non bush engineering side of the problem!!
Cheers
Stef
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Jackie, where in SA are you?
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Hi
I live in East Londen
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Hi Bob
How is your time to further test / check the engine governor side please?
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Jackie, you are lucky. EdDee on this forum is a genius and he lives in EL. I'm sure he can help you if he pops his head up.
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Hi Dax021,
I am hoping that Ed Dee is back on the seventh Jan as he was very willing to assist me
Will keep you guys posted on the outcome!!
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Hi Jackie, I did send you a dropbox link where you should be able to download the workshop manual. Since I have very little faith in modern technology, I also printed and scanned the relevant pages and have emailed them to you. I also attach a couple of photos of of the governor assembly on mine before I rebuilt it.
When you get my email, please see the top left hand corner of page 39, it is very possible that you have this speed adjustment on your engine. If the spring is damaged it might well bog down under load.
If EdDee lives locally he would be an ideal man to help resolve these issues.
Bob
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Hi Bob
Just opened mycover and governor looks identical to yours Does this gorvenor work on your genset I will look at that spring on P38 that you are referring to aswell If i do not come right I will contact ed on Monday to assist
Thx so long
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Hi Jackie, yes that type of governor works very well on my generator and holds RPM to within 1/2 a percent, even under heavy load. My generator is a Startomatic so it has a solenoid to switch the fuel rack on and off. It also has the adjustable throttle mechanism shown in the photo. the RPM can be adjusted by loosening and tightening the long bolts.
Bob
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Hi guys
Good news I found the fault on my lister st 2 8kva genset wrt volt drop under load In the control box there is a rectifier snd current tranformer The transf was fine but somehow previous owner swapped the bridge rect positive and negative The genset is now running inductive loads starting on 15 amps with minimall change in voltage and freq I just changed the bridge frectifier for good measure So all the stripping governors and injector checks are now done anyway but at the end a R40 bridge caused the fault
Thx to all for help much appreciated
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Well done Jackie, you managed to resolve a very unusual problem. I hope your Lister will now give you many years useful of service.
Bob
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Jackie, would you mind posting some photo's of the inside of your junction box. My Hoffberg generates fine, but the battery charger is putting out something like 60V. I'd like to compare, thanks.
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Hi Glort, I have seen the ignition coil gap problem so many times it always one of my first checks. Without a good spark it`s never going to light off. A trick I learned years ago and have used ever since is to put a strip of insulating tape on the flywheel. Adjust the coil until it touches the tape and tighten, spin the flywheel and remove the tape. Insulation tape is around 10 thou thick, I have never had it fail. It`s a lot easier than buggering about with feeler gauges, even if you know what the correct gap is supposed to be.
Bob