topic Re: Multisim Multimetr - problem RMS in Multisim and Ultiboard

Multisim Multimetr - problem RMS

vlad3156 — Sat, 27 Sep 2014 15:44:22 GMT

Hi, everybody! There was a problem with measurement of RMS. Multisim's multimeters show something unclear. I assembled the module of measurement of RMS and wanted to check on devices. Indications of devices differ from a calculated value of RMS of a signal... Maybe I incorrectly do something.???

Re: Multisim Multimetr - problem RMS

johnsold — Sun, 28 Sep 2014 02:20:41 GMT

I do not know what is in the RMS conversion module but I would be concerned about the time constant of the load circuit. With 47 nF and 40 ohms the time constant is 1.88 microseconds. Most physical RMS converters require time constants longer than the period of the input signal.

Lynn

Re: Multisim Multimetr - problem RMS

vlad3156 — Sun, 28 Sep 2014 06:21:24 GMT

The structure of the module is simple and primitive. It is collected on ideal components. I am disturbed that the multimeter 34401A (measures true RMS) has to show value 8.483. In, and shows absolutely other value. On a formula value 8.483 dismisses.