Hi All!
A related side-issue to be aware of is the leakage inductance of the isolating transformer: what is negligible for a 50/60 Hz transformer at 50/60 Hz may not be negligible in 400Hz usage of that same transformer, particularly if the current waveform is pulsed. Just check the voltage waveform if you suspect anything. As an example of this phenomena even without the factor of transformer design frequency: last week I needed to explore with an oscilloscope the function of a tiny 2.5 watt 220V 50Hz power supply embodying a series capacitor of 0.75 microfarad as a voltage-dropper. This should have drawn 6mS rectangular current pulses from the ac mains. For my safety I used the only available isolating transformer; a 50Hz 300watt isolating transformer. This had the effect that current pulse tops exhibited considerable "ringing" because of the transformer leakage inductance resonating with the series capacitor in the power supply. Not often a problem, but just remember the possibility. Richard Richard Marshall Laboratories, 30 Ox Lane, Harpenden, Herts., AL5 4HE, UK +44 (0)1582 460815 <http://www.design-emc.co.uk> www.design-emc.co.uk Member of the EMC Industry Association Richard Richard Marshall Laboratories, 30 Ox Lane, Harpenden, Herts., AL5 4HE, UK +44 (0)1582 460815 <http://www.design-emc.co.uk> www.design-emc.co.uk Member of the EMC Industry Association From: David Gelfand [mailto:[email protected]] Sent: 08 July 2016 17:25 To: [email protected] Subject: [PSES] Using 60 Hz isolation transformer at 400 Hz Esteemed colleagues, I have to prepare a debug setup for a DO-160 test, and we need to float the 400 Hz power supply. Can we use an isolation transformer rated at 60Hz, 150 VA? The EUT draws about 10W. Your input is most appreciated. Regards, David - ---------------------------------------------------------------- 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 <[email protected] <mailto:[email protected]> > 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) <http://www.ieee-pses.org/list.html> List rules: http://www.ieee-pses.org/listrules.html For help, send mail to the list administrators: Scott Douglas <[email protected] <mailto:[email protected]> > Mike Cantwell <[email protected] <mailto:[email protected]> > For policy questions, send mail to: Jim Bacher <[email protected] <mailto:[email protected]> > David Heald <[email protected] <mailto:[email protected]> > - ---------------------------------------------------------------- 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 <[email protected]> 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 <[email protected]> Mike Cantwell <[email protected]> For policy questions, send mail to: Jim Bacher: <[email protected]> David Heald: <[email protected]>
