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Author Topic: Generator voltage drops  (Read 553 times)

Jackie

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Generator voltage drops
« on: January 02, 2019, 05:28:00 AM »
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

ajaffa1

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Re: Generator voltage drops
« Reply #1 on: January 02, 2019, 05:57:45 AM »
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

Jackie

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Re: Generator voltage drops
« Reply #2 on: January 02, 2019, 06:13:40 AM »
Hi
Thx guys i tried posting photos but size is problem I am goin to take new ones less pixels snd post them shortly

ajaffa1

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Re: Generator voltage drops
« Reply #3 on: January 02, 2019, 06:18:43 AM »
Hi Jackie, some modern cameras have too great a resolution to send easily. looking forward to seeing what you have got.

Bob

Jackie

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Re: Generator voltage drops
« Reply #4 on: January 02, 2019, 08:09:59 AM »
Hi guys aatached the genset info Thx

Jackie

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Re: Generator voltage drops
« Reply #5 on: January 02, 2019, 08:13:04 AM »
Attached the ST2 engine plate

Jackie

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Re: Generator voltage drops
« Reply #6 on: January 02, 2019, 08:17:14 AM »
Sorry wrong pdf

ajaffa1

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Re: Generator voltage drops
« Reply #7 on: January 02, 2019, 09:08:32 AM »
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

Jackie

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Re: Generator voltage drops
« Reply #8 on: January 02, 2019, 09:15:57 AM »
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

dieselspanner

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Re: Generator voltage drops
« Reply #9 on: January 02, 2019, 09:28:55 AM »
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

Tighten 'til it strips, weld nut to chassis, peen stud, adjust with angle grinder.

Jackie

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Re: Generator voltage drops
« Reply #10 on: January 02, 2019, 09:48:34 AM »
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?

Jackie

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Re: Generator voltage drops
« Reply #11 on: January 02, 2019, 09:52:29 AM »
Hi
Something worth to mention is the diesel is gravity fed Should that be presurised or not? About a foot above engine head.

ajaffa1

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Re: Generator voltage drops
« Reply #12 on: January 02, 2019, 11:49:06 AM »
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

Jackie

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Re: Generator voltage drops
« Reply #13 on: January 02, 2019, 12:26:56 PM »
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

ajaffa1

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Re: Generator voltage drops
« Reply #14 on: January 02, 2019, 12:56:26 PM »
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)