Comment summary #18
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Comment 171 ... 180
| date | article | author | comment |
| 16 jan 2017 12:27:51 | Measuring capacitance and ESR | p thirumeni | what is Vrt in this (gray color) please explain. |
| 15 dec 2016 01:39:47 | Theory and Definitions | Qunyi Chen | I am convinced of your computation method. Thanks a lot! |
| 14 dec 2016 11:10:30 | Theory and Definitions | Freddy | It is not clear to me where you're going with the first part of your question. The real power absolutely depends on the DC-level of a AC-sine wave. What brought you to a different conclusion? |
| 14 dec 2016 02:19:59 | Theory and Definitions | Qunyi Chen | Hi Freddy, Thank you for your prompt feedback. Based on the general equation of real power in the equ 1. (in Power Measurements), the real power value stays the same for the following scenario: (1) For the same current signal in a sine wave shape without DC offset (2) For two voltage signals in a sine wave: one without DC offset, the other with DC offset. Does it mean that the DC offset of the voltage signal does not contribute to the real power (work or heat). It seems to be inconsistent with intuition. |
| 14 dec 2016 01:13:00 | Theory and Definitions | Freddy | There is no error in the conclusion: The active power, that is the power that is responsible for the work done, is the calculated average. You can not apply a calculation specific intended for for pure sine waves (without offset) on any other waveform (eg. a sinewave with offset). So the equation Vrms*Irms*cos(phaseAngle) will produce an erroneous result when applied on sinewaves with offset. Which shortcut calculation is allowed for a given signal shape is explained in the article Power measurements . |
| 12 dec 2016 23:21:53 | Theory and Definitions | Qunyi Chen | Sorry, typos in my last comment. I meant the conclusion only works for the signals with no DC offset. |
| 12 dec 2016 23:11:52 | Theory and Definitions | Qunyi Chen | Hi Freddy, It is interesting to see the conclusion that "The active power is always the average power. However, it may only be true for both voltage and current signals with DC offset. However, in my application, the voltage signal has a DC offset, the current signal has no DC offset. I find that Pav4 is not equal to the Pav1*cos(phaseAngle) or Vrms*Irms*cos(phaseAngle). Could you please confirm to this point? Thank you very much for your feedback in advance. |
| 19 nov 2016 21:15:36 | Arduino wattmeter | Iván | Ok, thank you so much for your time. |
| 19 nov 2016 20:23:29 | Arduino wattmeter | Freddy | Yes, you must use the peak values for calculating R1 and R3. Build in some reserve to avoid clipping when the values become somewhat bigger than expected. |
| 19 nov 2016 19:28:12 | Arduino wattmeter | Iván | Ok, thank you so much. And for calculate the resistors R1 and R3, I have to use the peak values of voltage (127v*√2=180v) and current (10A*√2=14.14A). Is this right? |