Re: [PSES] Current measurement
I likely used the same current probe that Ed did the Pearson Model 3525 because it is flat from 10 Hz to 10 MHz, I assumed that it would be flat in phase as well, but I didn¹t know if there was a fixed shift or not, so I measured that and it was 0 degree phase shift, so I could do what Ed did. Ken Javor Phone: (256) 650-5261 From: Edward Price Reply-To: Edward Price Date: Tue, 13 Feb 2018 11:51:29 + To: Conversation: [PSES] Current measurement Subject: Re: [PSES] Current measurement 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 here¹s 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 mailto:am...@westin-emission.no> > > Reply-To: Amund Westin mailto:am...@westin-emission.no> > > Date: Mon, 12 Feb 2018 22:04:44 +0100 > To: 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 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 <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/ <http://product-compliance.oc.ieee.org/> can be used for > graphics (in well-used formats), large files, etc. > > Website: http://www.ieee-pses.org/ <http://www.ieee-pses.org/> > Instructions: http://www.ieee-pses.org/list.html <http://www.ieee-pses.org/list.html> (including how to > unsubscribe) > List rules: http://www.ieee-pses.org/listrules.html <http://www.ieee-pses.org/listrules.html> > > For help, send mail to the list administrators: > Scott Douglas mailto:sdoug...@ieee.org> > > Mike Cantwell mailto:mcantw...@ieee.org> > > > For policy questions, send mail to: > Jim Bacher: mailto:j.bac...@ieee.org> > > David Heald: 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 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 <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/ <http://product-compliance.oc.ieee.org/> can be used for graphics (in well-used formats), large files, etc. Website: http://www.ieee-pses.org/ <http://www.ieee-pses.org/> Instructions: http://www.ieee-pses.org/list.html <http://www.ieee-pses.org/list.html> (including how to unsubscribe) List rules: http://www.ieee-pses.org/listrules.html <http://www.ieee-pses.org/listrules.html> For help, send mail to the list administrators: Scott Douglas mailto:sdoug...@ieee.org> > Mike Cantwell mailto:mcantw...@ieee.org> > For policy questions, send mail to: Jim Bacher: mailto:j.bac...@ieee.org> > David Heald: mailto:dhe...@gmail.com> > - -
Re: [PSES] Current measurement
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 mailto:am...@westin-emission.no>> > Reply-To: Amund Westin > mailto:am...@westin-emission.no>> > Date: Mon, 12 Feb 2018 22:04:44 +0100 > To: 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 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 mailto:sdoug...@ieee.org>> > Mike Cantwell mailto:mcantw...@ieee.org>> > > For policy questions, send mail to: > Jim Bacher: mailto:j.bac...@ieee.org>> > David Heald: 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 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 mailto:sdoug...@ieee.org>> Mike Cantwell mailto:mcantw...@ieee.org>> For policy questions, send mail to: Jim Bacher: mailto:j.bac...@ieee.org>> David Heald: 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 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 Mike Cantwell For policy questions, send mail to: Jim Bacher: David Heald:
Re: [PSES] Current measurement
Following opinions are mine alone, and were heavily influenced by my lunch-time burrito. Looked at one about 10 years past and decided the design was, in my opinion, 'marginal' per scoped safety standards; but have not looked at any recent product versions. Not accurate for high crest-factor stuff, and some inductive loads gave it temporary insanity. Readings were usable and reasonable over a limited temperature range (probably because of the current shunt's tempco) and for specific load types. Many comments floating around the internet on this product, so there is probably a decent technical write-up available. Brian From: alfred1520list [mailto:alfred1520l...@gmail.com] Sent: Monday, February 12, 2018 2:34 PM To: EMC-PSTC@LISTSERV.IEEE.ORG Subject: Re: [PSES] Current measurement While on the subject, any one familiar with the Kill A Watt meter? This listing sells for US$26 and free shipping: https://www.amazon.com/P3-International-P4460-Electricity-Monitor/dp/B000RGF29Q I swapped out the 2 mOhm current sensing resistor with a 0.2 ohm resistor (and of course greatly limiting the current capability) so I can measure standby power down to 10 mW. I did test with a 7 W incandescent light bulb and it reported reasonable readings. I tested are few phone chargers with nothing plugged and they idle at less than 50 mW. (But I don't know if I trust the figure down to decimal point:) It could be a really inexpensive way to get a reasonable (but not certification grade) power measurements. Best Regards, Alfred On February 12, 2018 1:36:10 PM PST, Brian O'Connell wrote: Will admit to having done this stuff with using microcontrollers and discrete sequential data channels and of sufficient sampling speed, but am subject to frequent bouts of idiocy. And this was for process control, and thus not a Type Test. Also, note that there is a difference in technique and equipment between power loggers and an analytical instrument. Best done with an instrument intended for this measurement; that is 'power analyzers'. Typically found on shelves at Keysite, Tektronix (nee Voltech), Ametek, Chroma, etc. And many Tek and keysite DSOs have a 'plug-in' for doing power measurements. All of this instrument-grade stuff can easily handle external sensors. Brian -Original Message- From: Amund Westin [mailto:am...@westin-emission.no] Sent: Monday, February 12, 2018 1:05 PM To: EMC-PSTC@LISTSERV.IEEE.ORG Subject: [PSES] Current measurement If you want to calculate t! he 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 Sent from my Android phone with K-9 Mail. Please excuse my brevity. - 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 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 Mike Cantwell For policy questions, send mail to: Jim Bacher: David Heald:
Re: [PSES] Current measurement
Shameless plug follows: check out the "Auditor": DIN rail, 6 channels, three phases, real-time over WiFi or 3G, highly configurable, Class 1, UL61010, etc. around US$200 includes CTs. Jon Keeble wattwatchers.com.au On Tue, Feb 13, 2018 at 8:36 AM, Brian O'Connell wrote: > Will admit to having done this stuff with using microcontrollers and discrete > sequential data channels and of sufficient sampling speed, but am subject to > frequent bouts of idiocy. And this was for process control, and thus not a > Type Test. Also, note that there is a difference in technique and equipment > between power loggers and an analytical instrument. > > Best done with an instrument intended for this measurement; that is 'power > analyzers'. Typically found on shelves at Keysite, Tektronix (nee Voltech), > Ametek, Chroma, etc. And many Tek and keysite DSOs have a 'plug-in' for > doing power measurements. All of this instrument-grade stuff can easily > handle external sensors. > > > Brian > > -Original Message- > From: Amund Westin [mailto:am...@westin-emission.no] > Sent: Monday, February 12, 2018 1:05 PM > To: 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 > > > 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 > Mike Cantwell > > For policy questions, send mail to: > Jim Bacher: > David Heald: -- Jon Keeble CTO m: 0407 842 840 e: j...@wattwatchers.com.au skype: jkeeble wattwatchers.com.au - 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 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 Mike Cantwell For policy questions, send mail to: Jim Bacher: David Heald:
Re: [PSES] Current measurement
While on the subject, any one familiar with the Kill A Watt meter? This listing sells for US$26 and free shipping: https://www.amazon.com/P3-International-P4460-Electricity-Monitor/dp/B000RGF29Q I swapped out the 2 mOhm current sensing resistor with a 0.2 ohm resistor (and of course greatly limiting the current capability) so I can measure standby power down to 10 mW. I did test with a 7 W incandescent light bulb and it reported reasonable readings. I tested are few phone chargers with nothing plugged and they idle at less than 50 mW. (But I don't know if I trust the figure down to decimal point:) It could be a really inexpensive way to get a reasonable (but not certification grade) power measurements. Best Regards, Alfred On February 12, 2018 1:36:10 PM PST, Brian O'Connell wrote: >Will admit to having done this stuff with using microcontrollers and >discrete sequential data channels and of sufficient sampling speed, but >am subject to frequent bouts of idiocy. And this was for process >control, and thus not a Type Test. Also, note that there is a >difference in technique and equipment between power loggers and an >analytical instrument. > >Best done with an instrument intended for this measurement; that is >'power analyzers'. Typically found on shelves at Keysite, Tektronix >(nee Voltech), Ametek, Chroma, etc. And many Tek and keysite DSOs have >a 'plug-in' for doing power measurements. All of this instrument-grade >stuff can easily handle external sensors. > > >Brian > >-Original Message- >From: Amund Westin [mailto:am...@westin-emission.no] >Sent: Monday, February 12, 2018 1:05 PM >To: 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 > >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 >Mike Cantwell > >For policy questions, send mail to: >Jim Bacher: >David Heald: -- Sent from my Android phone with K-9 Mail. Please excuse my brevity. - 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 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 Mike Cantwell For policy questions, send mail to: Jim Bacher: David Heald:
Re: [PSES] Current measurement
Will admit to having done this stuff with using microcontrollers and discrete sequential data channels and of sufficient sampling speed, but am subject to frequent bouts of idiocy. And this was for process control, and thus not a Type Test. Also, note that there is a difference in technique and equipment between power loggers and an analytical instrument. Best done with an instrument intended for this measurement; that is 'power analyzers'. Typically found on shelves at Keysite, Tektronix (nee Voltech), Ametek, Chroma, etc. And many Tek and keysite DSOs have a 'plug-in' for doing power measurements. All of this instrument-grade stuff can easily handle external sensors. Brian -Original Message- From: Amund Westin [mailto:am...@westin-emission.no] Sent: Monday, February 12, 2018 1:05 PM To: 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 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 Mike Cantwell For policy questions, send mail to: Jim Bacher: David Heald:
Re: [PSES] Current measurement
VA. You don't have any phase information when the two variables are measured separately. Ghery -Original Message- From: Amund Westin [mailto:am...@westin-emission.no] Sent: Monday, February 12, 2018 1:05 PM To: 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 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 Mike Cantwell For policy questions, send mail to: Jim Bacher: David Heald: - 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 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 Mike Cantwell For policy questions, send mail to: Jim Bacher: David Heald:
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 > Reply-To: Amund Westin > Date: Mon, 12 Feb 2018 22:04:44 +0100 > To: > 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 > > > 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 > Mike Cantwell > > For policy questions, send mail to: > Jim Bacher: > David Heald: - 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 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 Mike Cantwell For policy questions, send mail to: Jim Bacher: David Heald: