I lost all my emails from before on Leakage Current/Touch Current, but your replies were very helpful. Thanks.
I am trying to understand what affects the result of the Touch Current test according to IEC 60990. In our example, we are testing 230V single phase products with a grounded PE third pin on the power cord that connects to the chassis of the EUT. The 230V could be derived from split-phase, though we do not connect to the center tapped neutral, or one side of the 230V can be referenced to Earth (neutral), or the 230V could be isolated (not referenced to Earth) but still have the safety ground PE connected to chassis. When we test for Touch Current, the PE is opened (which isolates the EUT from Earth) and the Human Body Model circuit is inserted and metered. We take a measurement, reverse polarity on the AC Mains, then test again. We usually get similar results regardless of whether the AC is isolated or referenced to ground in some way. Now here is my question. We took a power cord, connected it to a line filter, then to a 150 watt 24Vdc power supply (which also has a live filter) that is loaded down with resistor loads, all mounted to a piece of sheet metal representing our chassis. We get a Touch Current of about 0.8mA, which seems typical. Then we added two 2000 watt dc power supplies (with internal line filters) driving heating elements and some ac powered heating elements and AC cooling fans. Our Touch Current test results went down to 0.2mA. How can this be? What phenomenon is lowering the test results driving more AC components in the EUT? Or are we doing something wrong? Thanks, The Other Brian - ---------------------------------------------------------------- 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 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: Mike Cantwell <mcantw...@ieee.org> For policy questions, send mail to: Jim Bacher: <j.bac...@ieee.org> David Heald: <dhe...@gmail.com> _________________________________________________ To unsubscribe from the EMC-PSTC list, click the following link: https://listserv.ieee.org/cgi-bin/wa?SUBED1=EMC-PSTC&A=1
