Capacitor on generator drives me insane

In summary,The Chinese diesel gene has a 15 ùF capacitor that keeps blowing up. It costs 18Au$ to replace each time and the city is 100km away.If it is inductive spikes blowing up the capacitor, it would help more to put capacitors in series to reduce the voltage across them than in parallel, but your capacitance would drop and you might not get the current surges your equipment needs, so you'd need 2 pairs of capacitors in series in parallel, or you could buy a capacitor with a bigger voltage rating, but I have no experience with this so this is just a guess.Thanks, Dragoon but the rating on the capacitor says 400 V and I
  • #1
Nitrax
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I run a 4.2 kw chinese diesel gene which has a 15 ùF capacitor on it. This capacitor keeps blowing up regularly. It cost 18Au$ to replace each time and the city is 100km away... Obviously it does 'nt like my big 2.4 kw grinder or my MIG welder (though the 10hp engine and 4.2 kw gene can handle it ). What should I do?? Can I place additional capacitors in parallel on the circuit? I understand this works like a shock absorber. Please don't tell me to get a bigger generator... Thanks for considering my question, I am not on the grid and depend on that gene.
 
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  • #2
Nitrax said:
I run a 4.2 kw chinese diesel gene which has a 15 ùF capacitor on it. This capacitor keeps blowing up regularly. It cost 18Au$ to replace each time and the city is 100km away... Obviously it does 'nt like my big 2.4 kw grinder or my MIG welder (though the 10hp engine and 4.2 kw gene can handle it ). What should I do?? Can I place additional capacitors in parallel on the circuit? I understand this works like a shock absorber. Please don't tell me to get a bigger generator... Thanks for considering my question, I am not on the grid and depend on that gene.

I think, if it is inductive spikes blowing up the capacitor, it would help more to put capacitors in series to reduce the voltage across them than in parallel, but your capacitance would drop and you might not get the current surges your equipment needs, so you'd need 2 pairs of capacitors in series in parallel, or you could buy a capacitor with a bigger voltage rating, but I have no experience with this so this is just a guess.
 
  • #3
Thanks, Dragoon but the rating on the capacitor says 400 V and I am dealing here with monophase 230 V. What about the 15uF (microfarads) I am not too sure what it means and how its value is worked out for a given situation. I am more familiar with the basics of resistance, voltage and intensity however capacitors are a bit of a head scratcher to me, sorry...
What you say about the capacitor array (2 in serie X 2 in parallel) makes sense, I feel like trying this...
 
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  • #4
Why not just use a Capacitor with a much higher voltage rating? It may cost more but it would be a fit-and-forget. If you want to make it up with two or more in series / parallel then it is a good idea to put a small load (say a low value mains light bulb - which would be a few kOhms) in parallel with each parallel pair of capacitors. This will ensure an equal share of any voltage drop across all of the capacitors.

btw, I imagine that the capacitor value is to suit the expected Power Factor. The PF describes the difference in Phase between current and voltage when you have a non-resistive circuit. Motors tend to be Inductive so a C will reduce / eliminate the circuit Reactance.
 
  • #5
Nitrax said:
Thanks, Dragoon but the rating on the capacitor says 400 V and I am dealing here with monophase 230 V. What about the 15uF (microfarads) I am not too sure what it means and how its value is worked out for a given situation. I am more familiar with the basics of resistance, voltage and intensity however capacitors are a bit of a head scratcher to me, sorry...
What you say about the capacitor array (2 in serie X 2 in parallel) makes sense, I feel like trying this...

Don't forget that 230 VAC has a peak voltage of 324 volts. You don't have a lot of margin with a 400 V capacitor. I concur that using a 15 uF at a higher voltage rating is probably the best solution.

How stable is the 230 volts on your generator? How much does it vary under varying loads? Does it ever go above 230 volts?
 
  • #6
Capacitor ratings are tricky.
230 volt RMS has a peak of 325 volt. 400 volt peak rated capacitor does not leave a large safety factor when operating on 230 volt RMS.

Is replacement capacitor rated for AC or DC. AC rating is usually MUCH lower than DC rating.

Some capacitors are rated for motor start use. These capacitors can only have voltage applied for a short period of time.
 
  • #7
Thanks guys for your replies. I can see a bit more clearly now.
Indeed the voltage varies and can be more than 240V
The replacement capa is probably off the shelf motor start capa.
How about electrolytic capacitors? What is the benefit compared to a dry capacitor?
I will look for a higher rated capacitor in 15uF. Not easy in North Queensland. Any internet address in Australia?
 
  • #8
Electrolytics are for dc and lower voltage applications. Just put a higher operating Voltage 15uF in. If necessary, order from abroad. It can't cost too much. Job done.
 
  • #9
The ability of a capacitor varies greatly with it's construction. Most common motor capacitors are constructed with paper and oil as the dielectric. This is a cheap but poor construction.
Polypropylene capacitors are much more robust.

Mike
 
  • #10
Leave it out. Your grinder and MIG welder will be fine.

When the Chinese generator finally goes, rectify your original mistake and buy American, Japanese or German generators.
 
  • #11
Indeed that's what a mate of mine did: He chucked off the chinese generator but kept the original diesel engine (these are ok) and fitted an italian generator and had no worries since (his conked out completely...)
Thanks Fellows I know what to do now. I realize this forum is really great and deals with many subjects of interest. Glad to be amongst you! Cheers
 

FAQ: Capacitor on generator drives me insane

1. What is a capacitor and what is its purpose?

A capacitor is an electronic component that stores and releases electrical energy. It is used to help regulate and stabilize the flow of electricity in a circuit.

2. How does a capacitor on a generator work?

A capacitor on a generator works by storing excess electrical energy and then releasing it when needed. This helps to smooth out the power output and prevent fluctuations and surges.

3. Why does a capacitor on a generator sometimes cause issues?

A capacitor on a generator may cause issues if it becomes damaged, faulty, or is not the correct size for the generator. It can also cause issues if it is not properly connected or installed.

4. How do I know if the capacitor on my generator needs to be replaced?

If you are experiencing electrical issues with your generator, it is possible that the capacitor may need to be replaced. Other signs of a faulty capacitor include bulging or leaking, strange noises, and visible damage.

5. Can I fix a faulty capacitor on my generator myself?

It is not recommended to try and fix a faulty capacitor on your generator yourself. Capacitors store high amounts of electrical energy and can be dangerous if handled incorrectly. It is best to have a trained professional replace the capacitor for you.

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