Ray and Chris I thought a lot of the effects on auxiliary equipment e.g. a PSU could be reduced if not eliminated by powering these via a coupling-decoupling network where it acts as a decoupler. Also this ensures the correct impedance to ground for the auxiliary equipment such as in figure 6 of EN61000-4-6 for the clamp injection method.
Ian Gordon From: r...@rpgarner.freeserve.co.uk [mailto:r...@rpgarner.freeserve.co.uk] Sent: 24 September 2003 13:39 To: Chris Chileshe; <emc-p...@majordomo.ieee.org> Subject: Re: DC PSU for conducted immunity testing to EN61000-4-6 Chris, I would suggest you need to change your test house. A good test house would already have power supplies available fed via filters to the test bench. They would also have ambient measurement information available to proof that their power supply was suitable for testing. I am also somewhat surprised that you make no reference to an ambient test having been performed on your set up. Also contrary to popular belief LISNs are not filters they only purpose is to provide a known impedance. I have in the past seen test houses cause more problems than they solve by not checking or using correct test set ups. Ray Garner EMC Consultant WRSL Message date : Sep 24 2003, 12:19 PM >From : Chris Chileshe To : emc-p...@majordomo.ieee.org Copy to : Subject : DC PSU for conducted immunity testing to EN61000-4-6 Group, After quite a struggle to get a product through conducted immunity tests (clamp method), I finally discovered that the weak link in the chain was in fact my laboratory power supply which I have been taking along with me to a nearby test house. The problem remained undetected for a number of reasons, not least that I had used the same setup before at a different test house using their PSU ( Solartron ASxxx) and had better results, but mostly because we were using a small chamber dedicated to conducted immunity tests and using a camera to monitor the behaviour of the EUT behind closed doors and not keeping an eye on the PSU. When we eventually tracked the anomalous behaviour of the EUT to the PSU, we tried LISNs and a different PSU both of which improved the test results significantly but the outcome was still not good enough from a product compliance point of view. Question 1: Is anyone aware of a power supply suitable for this type of testing? The EUT draws a maximum of 30mA at 12VDC. I have been unable to find any Solartron PSUs on the web; probably long discontinued. Question 2: Has anyone tried to build a filter for this sort of thing and would this be the way to go? Best regards - Chris Chileshe - Ultronics Ltd - UK (O.O.O.) _____________________________________________________________________ This e-mail has been scanned for viruses by MCI's Internet Managed Scanning Services - powered by MessageLabs. For further information visit http://www.mci.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: Ron Pickard: emc-p...@hypercom.com Dave Heald: emc_p...@symbol.com For policy questions, send mail to: Richard Nute: ri...@ieee.org Jim Bacher: j.bac...@ieee.org Archive is being moved, we will announce when it is back on-line. All emc-pstc postings are archived and searchable on the web at: http://www.ieeecommunities.org/emc-pstc
