Power Measurement Basics

[poynt99]

Mark,

For the record, the corrected videos have the identical content as before. When I originally assembled the various parts, they ended up in reverse order or something, and I did not notice. So the correction was done to the order, but the content has not changed, i.e. I did not make any new videos. Once again I apologize for any confusion this may have caused.

In terms of your suggestions and comments, although they are appreciated and stand on their own to augment what I presented, they are quite beyond my original intention. I feel the main points were clearly made in what I presented and from Luc's comment above, I expect clearly understood as well. I do this on my own time, even though I have a couple other important design projects on the go.

In summary, the main points of the Part1 video are:

1) If ever in doubt how to place your measurement probes in a circuit, keep KVL in mind and place your probes accordingly. i.e. move from component to component without flipping the leads. This is more pertinent to DMM measurements because scopes most often limit us as to how we can apply our probe leads.

2) If you must flip one pair of leads when using a scope (as we do when measuring source power), just invert the current channel within the scope itself. If you do not, your phase information will be inverted.

3) Power sources compute to a negative power, while loads compute to a positive power, if measured correctly.

4) 1)-3) are only important if phase or polarity is pertinent to one's argument or claims.

[poynt99]

Hi poynt,

both videos are clear, simple to understand and it makes sense the way you present it.

It's a good idea to split them up like you did.

Looking forward to the Oscilloscope videos... I guess you'll start with continuous DC circuits, then pulsed DC circuits and work your way up to AC circuits with phase shifts.

Thanks for the great job

Luc

Thanks Luc.

I trust that you truly understand and agree with everything in the video? Don't hold back if you don't, because all future concepts will be based on this first video.

[MarkE]

Mark,

For the record, the corrected videos have the identical content as before. When I originally assembled the various parts, they ended up in reverse order or something, and I did not notice. So the correction was done to the order, but the content has not changed, i.e. I did not make any new videos. Once again I apologize for any confusion this may have caused.

In terms of your suggestions and comments, although they are appreciated and stand on their own to augment what I presented, they are quite beyond my original intention. I feel the main points were clearly made in what I presented and from Luc's comment above, I expect clearly understood as well. I do this on my own time, even though I have a couple other important design projects on the go.

In summary, the main points of the Part1 video are:

1) If ever in doubt how to place your measurement probes in a circuit, keep KVL in mind and place your probes accordingly. i.e. move from component to component without flipping the leads. This is more pertinent to DMM measurements because scopes most often limit us as to how we can apply our probe leads.

I agree, but strongly suggest that the initial probe orientation should always be consistent with:  expected current flow through the load towards the circuit common.  This avoids the potential confusion of multiple negations.

2) If you must flip one pair of leads when using a scope (as we do when measuring source power), just invert the current channel within the scope itself. If you do not, your phase information will be inverted.

This is a place where I think the message and the demonstration are at odds.  Instrument inversions should be applied to make the measured instrument polarity match the assigned voltage and current conventions.  In your example both voltage and current through the load followed negative conventions.  Both channels should be inverted in order to register load power correctly.  Had you assigned voltage and current going the other way, then neither channel should be inverted to register load power correctly.  If one follows these rules then circuit analysis according to KVL exactly matches instrument readings, and power readings always follow established sign convention of positive values corresponding to loads.

3) Power sources compute to a negative power, while loads compute to a positive power, if measured correctly.

I absolutely agree.

4) 1)-3) are only important if phase or polarity is pertinent to one's argument or claims.

Obtaining measurement data consistently with established conventions is essential to clear communication.  I personally do not consider the points discussed above as optional.

[gotoluc]

Thanks Luc.

I trust that you truly understand and agree with everything in the video? Don't hold back if you don't, because all future concepts will be based on this first video.

Since I have no previous training or background in EE I can understand the logic in the measurement practice you've presented. So I think we can move forward from here.

However, I'm noting your logic is affecting those with EE background and wondering how it will all transform?

Thanks for being very open

Luc

[MarkE]

Since I have no previous training or background in EE I can understand the logic in the measurement practice you've presented. So I think we can move forward from here.

However, I'm noting your logic is affecting those with EE background and wondering how it will all transform?

Thanks for being very open

Luc

GoToLuc Poynt99's engineering is first rate.  He absolutely knows his subject matter.  My entire concerns revolve around how to effectively get his message across.