Greetings Joe and everyone, I can't speak for lab equipment, but I know that for UL 1950 (EN 60950/ IEC 950) my former employer (a recent NRTL who works/worked closely with the biggest) would always test with the mains switch both on and off. If you think about it, it makes sense to test with the mains switch off. Are you more likely to unplug a product that is on, or are you going to turn it off first? As you noticed, the mains capacitors do take longer to decay when the power switch is off. For this reason, I would have to side with the NRTL Engineer in question here - even if I am now working on the industry side of things.
Dave Heald marti...@appliedbiosystems.com wrote: > > We evaluate our laboratory equipment to UL 3101-1, CSA 1010.1 and EN > 61010-1. > > Section 6.10.3 of UL 3101-1 states "If plug pins of cord-connected > equipment receive a charge from an internal capacitor, the pins shall not > be HAZARDOUS LIVE 5s after disconnection of the supply". We have always > performed this test with the power switch in the ON position and would have > the unit running then unplug the power cord and take our reading on the > oscilloscope. We have never measured any voltages above the HAZARDOUS LIVE > limits of 30Vrms, 42.4V peak or 60Vdc. > Our new NRTL Engineer has now also requested us to perform this test with > the power switch in the OFF position. With the switch in the off position > our voltages after 5 seconds are close to line voltage. The NRTL is > considering this a failure. > > However, UL 3101-1 also states in Section 6.10.3 "For plugs receiving a > charge from an internal capacitor, the measurements of 6.3 are made to > establish that the levels of 6.3.1.3 are not exceeded." 6.3.1.3 requires > measuring the overall capacitance from the unit. Our NRTL states that > there is no method available to measure the overall capacitance of the > unit. > > Has anyone else in the group had any experience with this issue? Does > your NRTL require testing with the switch in the OFF position? Do your > units fail with the switch in the OFF position? Is it a failure just > because the voltage limits are exceeded, or is it only a failure if the > current and capacitance limits are exceeded. (Similar to the Permissible > Limits Requirements). Have you had any experience with NRTL's not being > able to measure the overall capacitance? > > All responses are greatly appreciated. > > Regards > > Joe Martin > Applied Biosystems > marti...@appliedbiosystems.com > > ------------------------------------------- > This message is from the IEEE EMC Society Product Safety > Technical Committee emc-pstc discussion list. > > Visit our web site at: http://www.ewh.ieee.org/soc/emcs/pstc/ > > To cancel your subscription, send mail to: > majord...@ieee.org > with the single line: > unsubscribe emc-pstc > > For help, send mail to the list administrators: > Michael Garretson: pstc_ad...@garretson.org > Dave Heald davehe...@mediaone.net > > For policy questions, send mail to: > Richard Nute: ri...@ieee.org > Jim Bacher: j.bac...@ieee.org > > All emc-pstc postings are archived and searchable on the web at: > http://www.rcic.com/ click on "Virtual Conference Hall," ------------------------------------------- This message is from the IEEE EMC Society Product Safety Technical Committee emc-pstc discussion list. Visit our web site at: http://www.ewh.ieee.org/soc/emcs/pstc/ To cancel your subscription, send mail to: majord...@ieee.org with the single line: unsubscribe emc-pstc For help, send mail to the list administrators: Michael Garretson: pstc_ad...@garretson.org Dave Heald davehe...@mediaone.net For policy questions, send mail to: Richard Nute: ri...@ieee.org Jim Bacher: j.bac...@ieee.org All emc-pstc postings are archived and searchable on the web at: http://www.rcic.com/ click on "Virtual Conference Hall,"
