# Power meters, to measure what?

#### Billy Mayo

Joined Mar 24, 2013
70
Power Meters, what have you used them for , what kind of circuits?

What were you measuring when using a power meter?

#### t_n_k

Joined Mar 6, 2009
5,447
I've used RF power meter to measure amplifier output power to load. Also used AC line power meter to measure single phase and 3-phase power.

#### Billy Mayo

Joined Mar 24, 2013
70
Measuring what with a power meter for single phase and 3 phase

#### WBahn

Joined Mar 31, 2012
24,976
Power Meters, what have you used them for , what kind of circuits?
Circuits in which I wanted to know how much power was being used.

What were you measuring when using a power meter?
Uh... power?

Could you provide a little bit more detail on what you are trying to find out?

#### WBahn

Joined Mar 31, 2012
24,976
Measuring what with a power meter for single phase and 3 phase
Measuring power. What else would you be measuring?

Are you trying to find out how a power meter works? What kind of power it is measuring?

Throw us a bone!

#### BillB3857

Joined Feb 28, 2009
2,506
Dynamometer to measure output power of BLDC electric motors.

#### Billy Mayo

Joined Mar 24, 2013
70
Yes give me examples of how u used power meters and what were u measuring? The power of what kind of signals? The power meter measures harmonics, for what?

#### WBahn

Joined Mar 31, 2012
24,976
Not all power meters measure harmonics. But if they do then you get a feel for how "clean" the power is, though you need to take measurements under different conditions to determine if the incoming power is dirty or if your load is dirty.

#### Billy Mayo

Joined Mar 24, 2013
70
If the incoming is dirty the harmonics would be what?

If the the load is dirty the harmonics would be what?

#### WBahn

Joined Mar 31, 2012
24,976
If the incoming is dirty the harmonics would be what?

If the the load is dirty the harmonics would be what?
You can't tell. That's why I said that you have to made additional measurements. If you disconnect the load and connect a resistive load instead and the meter still shows harmonics, guess which is dirty.

#### Billy Mayo

Joined Mar 24, 2013
70

What harmonics are clean and what harmonics are dirty?

Are the clean harmonics 1,3,5,8?
the dirty harmonics 2,4,6,7?

The AC outlet from the wall has harmonics too right?

#### Billy Mayo

Joined Mar 24, 2013
70
The AC outlet is 60 hz

The harmonics should be what for a clean AC outlet 60hz signal?

#### WBahn

Joined Mar 31, 2012
24,976
The AC outlet is 60 hz

The harmonics should be what for a clean AC outlet 60hz signal?
Before I know how best to explain, I need to know whether you understand what harmonics are. Do you? Please briefly describe what you believe them to be.

#### WBahn

Joined Mar 31, 2012
24,976

What harmonics are clean and what harmonics are dirty?

Are the clean harmonics 1,3,5,8?
the dirty harmonics 2,4,6,7?

The AC outlet from the wall has harmonics too right?
Any linear load is going to be clean.

Dirty means that it has harmonics at all. The more energy in the harmonics, the dirtier it is.

1 is not a harmonic, it is the fundamental.

#### t_n_k

Joined Mar 6, 2009
5,447
Referring back to the OP's original question (vague as it is) they might be distracted somewhat from the broader purposes of power measurement as applied to AC power systems. The intent of such measurement is surely not solely to determine power quality.

#### WBahn

Joined Mar 31, 2012
24,976
True, however note that it was the OP that specifically asked about harmonics. The bottom line is that it is extremely unclear just what the context of the OP's questions are. So do we try to answer in broad, general terms or in very narrow specific terms. I don't know the best answer to that.

#### studiot

Joined Nov 9, 2007
4,998
I guess from the text of the first post that this was a school 'project' question - to find out about the uses of power meters.

The OP needs to come clean about the detail.

#### Billy Mayo

Joined Mar 24, 2013
70
The output of a dc to ac invertor has harmonics going to a non linear load. The 7th harmonic is the most important one why? The ac waveform on the output of the invertor looks fussy or has fine hairs on the ac sine waveform these are the harmonics. Non linear loads have harmonics?

#### WBahn

Joined Mar 31, 2012
24,976
Okay, I'm done. Until you give some meaningful context for these seemingly random questions, you are on your own as far is I'm concerned.