# power factor .7 VS linear loads

Discussion in 'General Electronics Discussion' started by Danny Daviss, Mar 22, 2013.

1. ### Danny Daviss

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0
Mar 16, 2013
When measuring a units output with linear loads the percentage is off by 20%

1000 watts / by 120 VAC = max load is 8.3 ohms

Linear load of 8.3 ohms is off by 20%? from an 8.3 ohm Non-linear load?

So the power factor is .7?

2. ### (*steve*)¡sǝpodᴉʇuɐ ǝɥʇ ɹɐǝɥdModerator

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Jan 21, 2010
I will close this thread if you can't ask the question in a way we can answer it.

off by 20% from what?

For a pure resistance, yes. (Assuming 120VRMS -- can we assume that with you?)

How is it "off?". Does one appear to be 100W? How do you measure the power? (I hope it's not by measuring current)

No idea.

Now, ask the question again with these details provided.

3. ### Danny Daviss

67
0
Mar 16, 2013
Linear Load is 8.3 ohms max load Is 20% off from a Non- Linear Load that is 8.3 ohms Why is that?

If you circuit is designed for non linear load that is rated at max load of 8.3 ohms and you measure the outputs max load with a linear load at 8.3 ohms , Its 20% off , why?

is it a power factor .7 problem because the linear load doesn't have a power factor?

4. ### (*steve*)¡sǝpodᴉʇuɐ ǝɥʇ ɹɐǝɥdModerator

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Jan 21, 2010
Nup, still doesn't make a lot of sense.

You still need to tell me HOW it's 20% off, and HOW you're measuring the power.

As an exercise, I want you to try asking the question again, but with ALL the information I have asked you for. Do you understand?

5. ### Danny Daviss

67
0
Mar 16, 2013
The units is design for non linear load , max load is 8.3 AC current for a non linear load

I put my clamp meter, set it to AC current, clamp it on the black hot AC wire going to the "linear" load unit. The AC current on my clamp meter will read 8.3 AC current. This is max load that the until will take.

**The linear load is at 80% at 8.3 AC current**
** The Non Linear Load is at 100% at 8.3 AC current**

The Linear Load is 20% off from the Non linear Load, why?

Is it a power factor .7 problem?

6. ### Danny Daviss

67
0
Mar 16, 2013
units is 1000 watts at 120 AC

1000 watt divided by 120 ac = 8.3 amps

7. ### (*steve*)¡sǝpodᴉʇuɐ ǝɥʇ ɹɐǝɥdModerator

25,480
2,827
Jan 21, 2010
I still don't know exactly what you're asking, but I feel the answer is:

The non-linear load is not purely resistive and as such current leads or lags voltage (the power factor is suggestive of this).

Since the peak current does not match the peak voltage, you can't multiply them together to get power. If the power factor were due entirely to the load being reactive, I would think the power would be 700W, not 800W. Yet you still don't tell me how you determined the load was 80%, and I assume that means 800W.

Depending on what your secret circuit is, 8.3A with a power factor of 0.7 could represent 100% or more of the rated load.

You seem determined not to give enough information to us (EVER) to answer your questions. Why?