Any EE's in here - ? about generators & PF

[NL5]

Hopefully someone can answer this question. Say I have a generator with a PF around .6. If I am connecting a purely resistive load I'd get .6 Watts per VA. So, what I am wondering is, if I added a capacitor into the circuit, would it correct the PF at all, and would it put more power to the resistive load. Hopefully that makes sense.

Thanks in advance.

 

[MoMeanMugs]

Leading or lagging? I'm assuming it's inductive and lagging, so a capacitor would help.

 

[MoMeanMugs]

To answer your other question, no, more power isn't necessarily applied to the load. If your generator can keep up with your "purely resistive" load (no such thing), then I wouldn't worry about it. If the generator spins at a constant RPM and is independent of the output, you aren't gaining anything. If your PF sucked from your AC outlet, you're sending back power to the generation side, which the power company can't do anything with. As a residential customer, that's not a big deal because most power companies have cap banks on the distribution side. Industrial customers get charged extra for sending power back up the line.

 

[MoMeanMugs]

Forgot to add that if your generator is variable speed that's dependent on the load, then a capacitor will help with the wasted output. If the PF dips too low, it's possible to damage a cheap generator that doesn't have proper protection built in.

 

[jteef]

theoretically, yes. however your generator may not be built to deliver that extra power. You should only expect the generator to deliver the rated power output. There are also dangers to your generator and your load in having a large capacitor bank when the circuits are initially switched on and then later switched off. It's also hard to say what sorts of regulation circuitry in the generator may be working against you. Lastly, you also might not like the cost of the capacitors to get anything meaningful accomplished.

http://en.wikipedia.org/wiki/Power_factor

 

[NL5]

Thanks for the help.

I When I said purely resistive, I know that every circuit has inductance and capacitance.

This is for a project, and the generator will be built by me. To test the power output, it will be hooked up to a resistor, and I am just trying to eek out a few extra watts. Any other tips you guys have would be greatly appreciated.

 

[zzuupp]

MoMeanMugs

has the bases covered

 

[Gibson486]

Hmmm...the only thing this tell same is how apart in phase the voltage is from the current. So if you absolutely need maximum power transfer for the resistive load, then you need to add some reactance to the line. However, if your resistive load doesn't even come close to stressing the generator, then this exercise is not really needed.

 

[Gibson486]

To answer your other question, no, more power isn't necessarily applied to the load. If your generator can keep up with your "purely resistive" load (no such thing), then I wouldn't worry about it. If the generator spins at a constant RPM and is independent of the output, you aren't gaining anything. If your PF sucked from your AC outlet, you're sending back power to the generation side, which the power company can't do anything with. As a residential customer, that's not a big deal because most power companies have cap banks on the distribution side. Industrial customers get charged extra for sending power back up the line.

wouldn't a heater be a purely resistive load, or at least close to it?

 

[NL5]

wouldn't a heater be a purely resistive load, or at least close to it?

It's close to it, but even a piece of wire has inductance and capacitance.

 

[MoMeanMugs]

wouldn't a heater be a purely resistive load, or at least close to it?

It might be close, but it will never be purely resistive - physics wins every time! Even a big power resistor is made with wound wire, which gives it inductance. Little chip resistors have capacitance and can cause issues with sensitive timing in electronics. As longs as all the characteristics are accounted for, life goes on.

 

[Born2bwire]

It's close to it, but even a piece of wire has inductance and capacitance.

Not to mention the structure of rows of stretched coils are slightly inductive and capacitive too.