Author Topic: Voltage drop under load  (Read 18216 times)

guest23837

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Re: Voltage drop under load
« Reply #60 on: October 16, 2018, 02:48:23 PM »
Hi Ed

The neutral earth voltage is 272 volts When I connect the lamp it slowly drops to less than 200 from 235 ish

thanks

Paul

EdDee

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Re: Voltage drop under load
« Reply #61 on: October 16, 2018, 02:51:40 PM »
And the lamp isn't lit?

Is the output steady(around the 230V area)?

Send pic of the meter screen when its at the "less than 200" mark....(I suspect that the meter has autoranged down to millivolts maybe)

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!

guest23837

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Re: Voltage drop under load
« Reply #62 on: October 16, 2018, 03:29:57 PM »
Hi Ed

No the lamp doesnt light. Running the meter shows mid 230 volts and about 30 volts with the power off at the generator panel. Plug the lamp in its showing 104 volts powered off at the switch and 240 volts on the control panel. Turn on the lamp and the voltage drops and rises, fluctuates, needle swings about on the control panel.

Paul

EdDee

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Re: Voltage drop under load
« Reply #63 on: October 16, 2018, 04:06:46 PM »
Confirm - The AVR is still in the plastic tub and not touching ground anywhere with the above readings?
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!

guest23837

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Re: Voltage drop under load
« Reply #64 on: October 16, 2018, 05:15:08 PM »
Yes its totally isolated Ed

P

EdDee

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Re: Voltage drop under load
« Reply #65 on: October 16, 2018, 10:24:40 PM »
Hi Paul,

At this point I think you should call in an onsite pair of experienced eyes to take a look see for leaky insulation on the armature/rotor... This type of problem can occur if the unit has been used in a damp environment, particularly where there is salinity present. There appears to be a feedback onto the regulator circuit, most often caused by the things we have checked as above, but also possible if there is an insulation breakdown in both the fields and the rotor - stray voltages are presenting themselves to earth (probably from the fields) and being picked up by the AVR when N-E are tied, even by a fairly high resistance such as a light globe. Under "normal" conditions, the N-E can be linked without any form of influence to output, but, in the case of leakage to/from the rotor windings to/from the field windings, problems with output regulation by the AVR can occur....

About the last thing you could check, would be the wiring to and from the windings and brushes, look for any trapped wires that may be pinched and shorting to earth. All of the next lot of tests would require you to check for shorts or resistive links from the windings to earth. Whilst you have the bare requirements in the line of a digital test meter to do it, you might need to spend a bit of time at "Google University" to see how its done.

Pretty much, in a nutshell, you disconnect all the terminals on the alternator, unplug the AVR, unplug  any charging regulators and start looking for any resistance readings between each terminal and ground on the alternator.... Depending where the leak is found, that determines the course of action from there on.

Sorry that we coudn't nip this problem a bit earlier in the convo! Persevere and try and get it going to spec... that's a lovely little genset you have there and certainly worth investing a bit more time into!

I have a similar unit, its now 2 or 3 real beaut lightning strikes old... I have rebuilt it each time, the first took out the auto start switchgear, the second took out the auto changover circuitry, the third fried the genhead totally.... So its almost new now!! (Each bit was fabricobbled and re-inforced with something bigger and better at replacement!)  About the only original bits are the frame, covers, tank and engine!!

I can assure you, I would not have rebuilt mine each time would it not have been worthwhile!

Good luck!!

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!

guest23837

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Re: Voltage drop under load
« Reply #66 on: October 16, 2018, 11:40:33 PM »
Hi Ed

When I was doing the little tests today I had a look at the wires to check if something obviously wrong was visible. I noticed that the insulation on some of the wires disappearing into the alternator is cracked. Thats enough for me to stop using it. So what to do?
I'd have to pay someone to bring it off to get tested thats a minimum of €150 and it needs repairs even I know that. I could sell it as spares or repair but I'd feel I had to damage something (cut a wire maybe) so it was inoperative but what? If someone repaired the part I damaged they would still have a dangerous generator. The other thing I am considering is a new Mecc Alte brushless alternator. This would be in the region of €400.00 it would be new, safe, hopefully reliable etc. If it was sold Id get a few quid for it because of the engine but where do I go to get another diesel engine for €50?

http://www.ryalls.ie/used-tractor-machinery?skupeUrl=BC%3D3%26displayContact%3Dfalse%26NI%3D19716020%26PN%3D1%26RPP%3D10%26CN%3D3%26UI%3D513193%26SF%3D999999%26SA%3Dtrue

guest23837

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Re: Voltage drop under load
« Reply #67 on: October 17, 2018, 07:18:46 AM »
Its supposed to be a yanmar it's a 10 hp vertical. There's no restriction on buying these type of engines here except price, they aren't cheap. It' starts on half a turn or on the first pull, its noisy but all those little high speed engines are noisy. I bought it mostly for the engine. Ed was on the money about this and I'm grateful for the input from you guys it could have ended badly! When I finally figured out how to use the multimeter I was surprised at how stable the frequency was so a new alternator makes sense right now, you never know a different generator with a fcuked engine could come along!

EdDee

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Re: Voltage drop under load
« Reply #68 on: October 17, 2018, 09:13:15 AM »
Hi JD,

On my last rebuild of my unit, I manged to get a scrapped 6KVa petrol screamer with a "leg out of bed" .... Pulled the alt and fitted it to the Yanmar.... Problems solved!

Was the cheapest and easiest solution at the time.... Used the tank as an extra for my Lister, Frame became something else, engine I chopped up and smelted...except for the crank, which I machined big end off, mounted it in the 1/2 of the crankcase, fitted a pulley where the big end was, mated another small alt to the other side and gave it to a mate as a belted alternator...

Your best bet is to spend 5 quid and get an obviously poked oil pisser that nobody wants.... The Alts on a mechanically buggered unit would generally be ok to re-use.... People seem to think that when the engine's inside's have become outside's the alt is worth nothing....not true!

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!

mike90045

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Re: Voltage drop under load
« Reply #69 on: October 17, 2018, 05:38:55 PM »
from the grounding PDF :   the high voltage winding (earthed through a neutral resistor).

I'm pretty sure that's not the english I speak, earthing through a neutral resistor ?

guest23837

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Re: Voltage drop under load
« Reply #70 on: October 19, 2018, 07:21:39 PM »
Little update - my brother brought me to a collector of stuff he had a chinese generator that seized. €40.00 changed hands and I came home with a brushless alternator. The capacitor lugs got broken on the trip home. Anyhoo it's connected and making power but only 200 volts. I want to replace the capacitor but there's no markings on it. Apart from the buy and try method is there any way to determine the uf rating on these. ?
Thanks

BruceM

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Re: Voltage drop under load
« Reply #71 on: October 19, 2018, 10:27:13 PM »
The cheapest capacitor meter will work just fine.

guest23837

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Re: Voltage drop under load
« Reply #72 on: October 19, 2018, 10:48:27 PM »
Thanks mate the meter is my new toy and obviously as a man I didnt NEED to read the instruction manual. I have worked out that the capacitor is 36uf so im thinking 40 would increase the voltage slightly? I was also thinking of adding 150 rpm any other suggestions welcome

BruceM

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Re: Voltage drop under load
« Reply #73 on: October 19, 2018, 11:40:51 PM »
I'm not familiar with capacitor regulated alternator designs, but hopefully someone else is and can help you.


mike90045

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Re: Voltage drop under load
« Reply #74 on: October 20, 2018, 12:19:46 AM »
>  is there any way to determine the uf rating on these

Capacitor meters.  Been around for years, and they should be more than enough to measure the cap.

Just remember, it may leave a charge on the cap, which can "bite" - sometimes fately .  Be careful.