What is a reactive load?

[Mynameismcgyver 10+ year member]

Saw this term in a amp review...Saying it produced more power under a reactive load...In English, what does this mean?

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[22mountaineer 10+ year member]

Reactive is returned to the source, resistive is not.

 

[Mynameismcgyver 10+ year member]

Alright...So by them saying they gained more power by using a reactive load...Give me an example of doing it using the amp.

Thanks.

 

[22mountaineer 10+ year member]

By using resistive you would have to have your source constantly getting power from somewhere.. Reactive is a loop

 

[22mountaineer 10+ year member]

Also it will not be a big enough difference to notice,

 

[22mountaineer 10+ year member]

But you will not be in phase so there will not be a resistive circuit

 

[Haunz 10+ year member]

A reactive load has capacitance and inductance along with resistance...

The reason why it seems that the amp put out more power into that reactive load is because it was 'apparent power' that was being measured... If you accounted for power factor you would see that the amp actually delivered less power then what was measured...

You can think of apparent power as energy leaving the amp which is in turn fed back into the amp; so it never really leaves //content.invisioncic.com/y282845/emoticons/fyi.gif.9f1f679348da7204ce960cfc74bca8e0.gif

 

[Ed Lester 10+ year member]

basically your speakers/subs are a reactive load. A resistor is a resistive load.

 

[Immacomputer 10+ year member]

In a reactive load (one that has inductance and capacitance), you can store and release energy. Capacitors store voltage while inductors store current. In a purely resistive load (no capacitance or inductance) your power is measured by multiplying the current times the voltage. That will give you a power measurement in Watts. In a reactive load, when you multiply the voltage and current, you get the apparent power measured in Volt Amps. This apparent power (VA) is greater than the resistive power (watts) because of the stored energy properties of capacitance and inductance. The phase of the power is also going to be different as the current can either be leading or lagging behind the voltage. This leading and lagging property means that the voltage and current are out of phase by a certain amount. If they're out of phase, then you can't just multiply them together to get your actual power and you have to apply the power factor. The power factor is going to be the cosine function of the angle between the resistive power and reactive power. That leads to the power triangle relationship where you can view power as a phaser on a polar coordinate plane.

So basically, the amp isn't supplying more power under a reactive load but the power it is producing is being stored and sent back by the capacitance and inductance of the circuit elements. The max power an amp can produce (in watts) will never increase under a reactive load.

 

[joetama 5,000+ posts]

Impedance vs. resistance... //content.invisioncic.com/y282845/emoticons/wink.gif.608e3ea05f1a9f98611af0861652f8fb.gif

 

[Immacomputer 10+ year member]

Impedance vs. resistance... //content.invisioncic.com/y282845/emoticons/wink.gif.608e3ea05f1a9f98611af0861652f8fb.gif

But resistance is impedance as is reactance. //content.invisioncic.com/y282845/emoticons/wink.gif.608e3ea05f1a9f98611af0861652f8fb.gif

Impedance is the combination of reactance and resistance. You can't sum the two because reactance is a complex number (remember that imaginary number "i" from algebra? That doesn't just exist in fairy tales) and so we use impedance which has a magnitude and phase.

 

[audioholic 5,000+ posts]

Nerds.

 

[Immacomputer 10+ year member]

It's OK, I'll soon be getting paid quite well to be a nerd.

 

[IDSkoT 5,000+ posts]

It's OK, I'll soon be getting paid quite well to be a nerd.

x2

 

[audioholic 5,000+ posts]

No, you'll be getting paid well to be smart. //content.invisioncic.com/y282845/emoticons/tongue.gif.6130eb82179565f6db8d26d6001dcd24.gif