Hi Rich, Your comments remind me that I prefer to take each step in an analysis with my "closest to the pin" estimate, and afterwards if I want to be conservative, apply some overall discounting factor. The alternative method of taking a conservative estimate for each step may lead to unrealistic and non-transparent results.
Cheers, Gary Tornquist From: Richard Nute <[email protected]> Sent: Sunday, March 13, 2022 6:59 PM To: [email protected] Subject: Re: [PSES] Medical Device Leakage Current Production Line Test Setup Comments by Savino Macias and Boštjan Glavič triggered some thoughts about EARTH LEAKAGE CURRENT (IEC 60601-1 defined term) and measurement schemes. 1. EARTH LEAKAGE CURRENT in IEC 60601-1 (and most other safety standards) is the current in the protective earthing conductor from the equipment to the neutral conductor of the mains supply. 2. The transformer T1 in Figure 13 is a variable transformer (or equivalent source) to get 110% of the equipment highest rated voltage. 3. The transformer (or source) need not be isolated from the mains as the point of connection of the leakage current meter, MD, is to the neutral conductor. Note that the circuit in Figure 13 has one pole of the transformer connected to ground (making that pole the neutral conductor). However, the ground is not in the measurement circuit, but the ground may be important to protect measurement personnel. 4. The MD (Figure 12) measures the voltage across a 1 k-ohm resistor. Other standards measure the voltage across a 2 k-ohm resistor. The measured EARTH LEAKAGE CURRENT in IEC 60601-1 is slightly higher than other safety standards (e.g., those that cite IEC 60990). 5. Supposedly, the resistor values of 1 k-ohm and 2 k-ohm represent the body resistance at 50 to 60 Hz. Inserting a real body in place of the MD will result in 10% or less of the measured leakage current. 6. EARTH LEAKAGE CURRENT in IEC 60601-1 (and most other safety standards) presumes an open ground (fault) in the installation mains supply, not in the equipment. However, the equipment power cord or plug may get damaged so as to open the equipment ground connection to the installation ground. (This is common in North America.) 7. I've often wondered why we measure EARTH LEAKAGE CURRENT with a simulated body when we're characterizing the equipment. The difference between the IEC 60990 leakage current measurement circuit and an ordinary ammeter is at most a 5% pessimistic difference (and even less using the IEC 60601-1 measurement circuit). Best regards, Rich From: Boštjan Glavič <[email protected] <mailto:[email protected]> > Sent: Thursday, March 10, 2022 9:38 PM To: [email protected] <mailto:[email protected]> Subject: Re: [PSES] Medical Device Leakage Current Production Line Test Setup Dear Savino Please check specs of your AC programmable source if output is isolated (floating) . Normally it is not. Therefore additional isolation transformer is needed. Best regards Bostjan SIQ Ljubljana Get Outlook za Android <https://aka.ms/AAb9ysg> _____ Od: Savino Macias <[email protected] <mailto:[email protected]> > Poslano: sreda, 9. marec 2022 21:33 Za: [email protected] <mailto:[email protected]> <[email protected] <mailto:[email protected]> > Zadeva: [PSES] Medical Device Leakage Current Production Line Test Setup Is anyone familiar with the test setup for doing Leakage Current tests? I have a device with input voltage of 100-240V, so my production line test needs to be done at 264V (110% of highest rated voltage). Would I use a programmable AC power supply to do this test (along with the leakage test equipment, of course)? Also, an isolation transformer is required per the 60601-1 standard. Would a programmable AC power supply act as the isolation or would an isolation transformer still be needed? Thanks, Savino Macias Canon Virginia Inc. - ---------------------------------------------------------------- This message is from the IEEE Product Safety Engineering Society emc-pstc discussion list. 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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]>
