If a battery connects to a signal cable in addition to charging and discharging a dc bus (for instance), then that signal cable is required for the test in any EMI standard. In the case of just such a battery, it reports status to an annunciator panel so that operators can monitor its state of charge. It is business as usual to include that cable and a simulated panel in the test, although the panel, not being under test, is outside the test chamber. Ken Javor Phone: (256) 650-5261
From: Cortland Richmond <[email protected]> Reply-To: <[email protected]> Date: Fri, 24 Aug 2012 14:23:45 -0400 To: <[email protected]> Cc: <[email protected]> Subject: Re: [PSES] "Smart" Batteries Hi, Ed. I wasn¹t suggesting the EUT would be an exposure problem, as the usual emissions are far too low; just that a mannequin made for whole body SAR would be almost ideal. You got around that by measuring the difference in emissions. Bingo! The point I wanted to make was that 461 tests need to closely approximate the actual use environment, which a passive charge discharge/recharge cycle doesn¹t do for actively communicating smart batteries. Cheers, Cortland Richmond KA5S On 8/24/2012 1313, Ed Price wrote: > Re: "Smart" Batteries > > > Cortland: > > > > I didn¹t get into other details, but yes, we were concerned about human RF > exposure at the 225 MHz data link frequency. However, the modulation scheme > was very low duty cycle. First, we had a message rate of once per 10 seconds. > Then, the individual participant was assigned a time-slot that allowed for > roughly a 9 millisecond total message. And the message itself was composed of > frames of data, which consisted of digital words made of digital bits (offs > and ons). You could sure see it with a Peak detector, but the Average was > undetectable. We did measurements with a QP and Average detector, plus > measurements with a bolometer type power density meter, in addition to > calculating the power from Peak measurements and typical duty cycle values. > Every way we looked at it, the human exposure was very low. > > > > We tested the soldier-worn system on a mannequin to 461 conditions; there were > never any connecting wires, although we did have to supply real-time GPS to > the EUT. It was also helpful that the soldier-worn harness also had optical > ports that we could use. I would have preferred a mannequin that was more > representative of a human torso, but out PVC pipe and foam rubber mannequin > produced emission results very similar to a man-worn setup. We also did > extensive antenna pattern testing with real humans crawling around in the > dirt. The battery is never charged while on the soldier, so the man-worn > equipment really has only one mode of operation. The batteries are usually > installed before the training session, but a long session might require a > field re-supply, so a quantity of batteries could be transported, typically on > an HMMWV. Batteries are never charged in the field, or while in the harness, > mainly because it¹s easier to move charged batteries than the chargers > themselves. > > > > As an aside, we sold systems to the British, and they had us include > enhancements such as gadgets that simulated land mines & IED¹s, so not > everything was man-worn. And of course, there were other devices in this > product family that were intended for vehicles and weapons, but that testing > was similar to traditional 461 testing. > > > > The concern about ³very long² cables as part of the EUT may be going away. > System designers are finally embracing optical cables instead of using a > fire-hose sized signal and control cable bundles. OTOH, I was seeing a rise in > designs that tried to use COTS Wi-Fi (or similar) to network very local boxes > instead of using signal & control cables. There are a lot of EMC problems with > this, so we will still have lots of job security. J > > > > > > Ed Price > > El Cajon, CA > > USA > > > > > > - ---------------------------------------------------------------- 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://listserv.ieee.org/request/user-guide.html 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]> - ---------------------------------------------------------------- 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://listserv.ieee.org/request/user-guide.html 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]>
