The Accidental Smallholder Forum
Smallholding => Equipment => Topic started by: Tala Orchard on January 14, 2014, 07:55:46 am
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Can anybody help or explain why my 6kw generator seems to be producing less wattage where as before it would run the borehole pump, fridge, lighting, heating and oven in our lodge it now struggles we need to switch off appliances so as to run one of the higher consuming appliances.
Need to know what I can do about it, if anything?
Many thanks in advance for any assistance.
Tala
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Hi
I know next to nothing about gennies
but does it need servicing?
How old is the alternator?
SV
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difficult to say. What happens when you try to run too many things? Does it hold revs OK when a load is added?
possibilities:
sticking speed regulator allowing revs (and Hz) to drop when new load added.
running speed set too low.
voltage out low.
Have you replaced one or more appliances with higher rated ones since it was working normally.
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I thought about a low voltage problem -have you measured the voltage at the appliances? Is it a house circuit problem?
If the motor is down on power the electrical output will also be. When was it last serviced? Sounds as though it has been pushed hard for an extended period of time.
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The genny might be indicated as 6KVA , that is the energy needed to produce the same heating effect as a DC.current
So if you divide the KVA by 1.141 ( power correction factor )you will have the load the genny can supply in AC amps . Quite often the amps available for prolonged generation of several hours is often almost 3/4 of the power corrected amperage figures.
explanation
My Honda suitcase petrol genny is sold as a 3.13 kva genny, it is guaranteed to give 2.8 kva pure 50 cycles per minute sine wave at a constant 220 volts all this equates to a true 10 amps @ 220 volts ac being available when the genny is fully loaded ( it's our business computers , oil central heating & LED lighting stand by genny )
This will be the ideal theoretical current for the alternator strapped to a test bed , it will in fact be a few amps lower when you take into account the friction losses of the engine and thickening oil , worn injectors ( if it is a diesel )or a carbonized exhaust silencer.
If it is a diesel Petter look carefully with a torch at the holes in the silencer if they are sooty it needs cleaning as follows , carefully take the silencer off and use a blowlamp to heat it to dark red hot , give it a few gentle knock with a lump of wood to loosen the burning carbon, which will help burn out the rest of carbon thus reducing the sooty deposits which causes restrictions to the free flow of exhaust gasses out the engine . Getting rid of this back pressure of the exhaust in turn gives you quite a noticeable increase in power.
if your behind in changing the engine oil give it an oil change .. thick dirty oil increases friction so you lose power. A dirty air filter also reduces power ..so if you have the genny in a shed and the exhaust gasses can be sucked back in the air filter your scoring an own goal . if it is an oil bath type filter empty the oil out of the sump bowl , wash the bowl in petrol, let it dry before putting it back , wash the element out in petrol and let it dry off before refitting & refilling the bowl with clean engine oil .
If it is a paper element filter have a look at it, ( the efficiency of a slightly darkened filter will knock the genny out put down considerably ) fit a new one as you can't easily successfully clean a sooted up paper filter element .
Blowing it off with compressed air is not a sound or safe option for it drives carbon particles even deeper in to the pores of the paper element , if you're not masked up you'll also be breathing carbon particles in for days as they will also be on your clothing and in your hair & nostrils
Do make sure that the electrics you plug into the genny are not faulty and drawing more current than they should, also make sure that there are not too may things plugged in( add up all the wattages of everything that's plugged in to check it only comes to about 3/4 of the power factor adjusted ampere rating .
One thing to do is unplug everything , then plug them back in one at a time having taken the earlier one out again to see if any particular switched on device /equipment drags the genny down .
If the earthing of the genny set up is not right you can sometimes find an immersion heater will drag thing down as it starts to break down the elements insulation ( same for the washing machine heater element .
If there is no noticeable increase in power you may need to do a compression test and /or a top / full overhaul etc.
One thing that is very very useful for folk who use a genny for their power is to save up and buy a clip on the cable ammeter from an electrical wholesaler's online shop ( £30 ish ??? ).
Which when clipped on over the outside of a cable will show the current being drawn / supplied through bit ...... make sure it covers the current ratings for your generator
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hi test the voltage if it is reading low but increases when you manually increase engine speed (opening the throttle by hand at the governer) then it is likely that the automatic voltage regulator ( AVR ) needs replacing.