I had to measure inrush power and power during some function switching. I had a really nice 4 channel digital oscilloscope with math functions, so here's what I did.
1. I put a 10x voltage probe on Channel 1 and verified the the probe factor. 2. I put a 1x Pearson current probe (very flat response up through 10 MHz) on Channel 2 and verified the probe factor. 3. I chose the waveform math to multiply Channel 1 times Channel 2 and display this in Channel 3. This gave me Vrms displayed on Channel 1, Arms on Channel 2, and real time Watts RMS displayed on Channel 3. 4. I could then use the MAX & MIN cursor functions to find the highest power draw anywhere along that power waveform. I was able to trigger off the Channel 1 Voltage, but I could have triggered on the current or even used an external trigger. Plotting the Power waveform was really interesting. Ed Price WB6WSN Chula Vista, CA USA -----Original Message----- From: Ken Javor [mailto:ken.ja...@emccompliance.com] Sent: Monday, February 12, 2018 1:09 PM To: EMC-PSTC@LISTSERV.IEEE.ORG Subject: Re: [PSES] Current measurement Unless you can look at both voltage and current on an o'scope and compute phase angle between them, you are only measuring apparent power. Ken Javor Phone: (256) 650-5261 > From: Amund Westin <am...@westin-emission.no<mailto:am...@westin-emission.no>> > Reply-To: Amund Westin > <am...@westin-emission.no<mailto:am...@westin-emission.no>> > Date: Mon, 12 Feb 2018 22:04:44 +0100 > To: <EMC-PSTC@LISTSERV.IEEE.ORG<mailto:EMC-PSTC@LISTSERV.IEEE.ORG>> > Subject: [PSES] Current measurement > > If you want to calculate the consumed power (W) in a 1-phase AC > circuit, you can use a current clamp-on device to measure the current > in one lead/wire and multiply with the applied voltage. > But with such a current clamp on device, to we measure the apparent > power > (VA) or the real power (W)? > > Best regards > Amund > > - > ---------------------------------------------------------------- > This message is from the IEEE Product Safety Engineering Society > emc-pstc discussion list. To post a message to the list, send your > e-mail to <emc-p...@ieee.org<mailto:emc-p...@ieee.org>> > > All emc-pstc postings are archived and searchable on the web at: > http://www.ieee-pses.org/emc-pstc.html > > Attachments are not permitted but the IEEE PSES Online Communities > site at http://product-compliance.oc.ieee.org/ can be used for > graphics (in well-used formats), large files, etc. > > Website: http://www.ieee-pses.org/ > Instructions: http://www.ieee-pses.org/list.html (including how to > unsubscribe) > List rules: http://www.ieee-pses.org/listrules.html > > For help, send mail to the list administrators: > Scott Douglas <sdoug...@ieee.org<mailto:sdoug...@ieee.org>> > Mike Cantwell <mcantw...@ieee.org<mailto:mcantw...@ieee.org>> > > For policy questions, send mail to: > Jim Bacher: <j.bac...@ieee.org<mailto:j.bac...@ieee.org>> > David Heald: <dhe...@gmail.com<mailto:dhe...@gmail.com>> - ---------------------------------------------------------------- This message is from the IEEE Product Safety Engineering Society emc-pstc discussion list. To post a message to the list, send your e-mail to <emc-p...@ieee.org<mailto:emc-p...@ieee.org>> All emc-pstc postings are archived and searchable on the web at: http://www.ieee-pses.org/emc-pstc.html Attachments are not permitted but the IEEE PSES Online Communities site at http://product-compliance.oc.ieee.org/ can be used for graphics (in well-used formats), large files, etc. Website: http://www.ieee-pses.org/ Instructions: http://www.ieee-pses.org/list.html (including how to unsubscribe) List rules: http://www.ieee-pses.org/listrules.html For help, send mail to the list administrators: Scott Douglas <sdoug...@ieee.org<mailto:sdoug...@ieee.org>> Mike Cantwell <mcantw...@ieee.org<mailto:mcantw...@ieee.org>> For policy questions, send mail to: Jim Bacher: <j.bac...@ieee.org<mailto:j.bac...@ieee.org>> David Heald: <dhe...@gmail.com<mailto:dhe...@gmail.com>> - ---------------------------------------------------------------- This message is from the IEEE Product Safety Engineering Society emc-pstc discussion list. To post a message to the list, send your e-mail to <emc-p...@ieee.org> All emc-pstc postings are archived and searchable on the web at: http://www.ieee-pses.org/emc-pstc.html Attachments are not permitted but the IEEE PSES Online Communities site at http://product-compliance.oc.ieee.org/ can be used for graphics (in well-used formats), large files, etc. Website: http://www.ieee-pses.org/ Instructions: http://www.ieee-pses.org/list.html (including how to unsubscribe) List rules: http://www.ieee-pses.org/listrules.html For help, send mail to the list administrators: Scott Douglas <sdoug...@ieee.org> Mike Cantwell <mcantw...@ieee.org> For policy questions, send mail to: Jim Bacher: <j.bac...@ieee.org> David Heald: <dhe...@gmail.com>
