Re: Li-ion Batteries
Doug, Thanks for the advice. I'll be having some discussion with the design team to bring out your pointers. As they are currently still in the designing stage. But my current concern is when we talk to the Li-ion batteries suppliers, what compliance documents should we request from them. At least to proof that the batteries are indeed safe or meeting the minimum requirements. I'm new to Li-ion batteries and not sure that standards that it needs to conform to. UL1462 UL2054 are standards which was found in UL website. Is there a European standard for Li-ion batteries? Is there a battery directive? If yes, what standards is applicable? CE mark required? Regards Koh Massey, Doug C. wrote: Well, I haven't seen anybody weigh in on this yet, so here goes. First of all, Li-Ion batteries have tremendous energy density. I recently watched some videos of Li-Ion cells failing an overcharge test, and it was really impressive. These things looked like a roman candle going off ! They would make great highway flares. So here's my advice and hopefully I can answer some of your questions. 1. Vent. Period. If a cell vents inside your device, the pressure build up inside your battery pack enclosure could be tremendous if an adequate venting mechanism is not provided. 2. In addition to providing reliable overcharge, overvoltage, reverse polarity protection, consider controlling the maximum discharge current as well. With today's cells, most (probably all) incorporate a PTC device built into the cell to interrupt excessive current. I personally would not recommend relying solely on this protective device alone. However, that built-in device will allow you to pass the rapid discharge test of clause 4.3.21 (UL1950 3rd Ed. reference), where you must defeat any current or voltage limiting device in the battery load circuit. 3. Protection circuits for Li-Ion are typically based on an IC controller along with some discreet components making up the circuit. Last time I dealt with getting a Li-Ion pack approved, that IC is not UL recognized, and we could not find any control chips that are. Expect to be asked by the test house to provide technical assistance in determining worst-case faults in that circuit, so that they can ensure the safety of that control circuit under any conceivable single fault condition. Expect the test house to focus more on the battery and associated control circuits than anything else in your portable device, just as they might focus more on the primary side of an AC supply. The greatest energy source, and greatest safety hazard, in your product will be the battery. What standards must these Li-ion batteries needs to comply before we purchase them? UL2054 or UL1642 standards or both ? What about European standards ? 4. UL 1642 is the applicable U.S. standard for cells. UL 2054 could be applied as well to a Li-Ion battery pack as well, but in your case, the requirements within the overall product standard (60950?) should apply. Not sure about the equivalent CENELEC standard. 5. When discussing battery issues, please refer to them as cells or battery packs, so that we all know whether you mean an individual cell or a pack made up of two or more connected cells. I am making assumptions that when you say battery, what you mean is, a removable battery pack, but I guess it's conceivable to have a widget that the cells are permanently mounted inside of, although I can't conceive why anyone would do that, since the typical life of a Li-Ion is going to be around 500 charge-discharge cycles. In the case of a Li-Ion battery pack, the only information required on the pack is the voltage and the IEC symbol referring the user to the operator's manual, where you will be required to have statements regarding the proper replacement of the battery, statements telling the operator not to disassemble, crush, or incinerate the battery pack, and not to operate above a certain temperature (usually around 200 C - this is very important, since people are always using their ITE devices in a friggin walk-in oven at 392 F to crush, disassemble, or incinerate their Li-Ion battery packs). This max temperature comes from the conditions of acceptability for the cell itself, and will vary between brands. Alternately, all of this info can be on the battery pack itself, but it's a lot of text that you may not be able to fit - 60950 does allow the warnings to be in the operator's service guides. We might want the supplier to put our company name on the battery, what can we do (or request from the supplier) to protect ourself on liability issue? If you figure out a way to get your company excused from any liability resulting from use of a product that your company produces, please let me know. Name or no name on it, if you sell that product, you could be liable for any damages. As always, independent third party evaluation of your product's compliance to the
Amended EMC Directive
Hello All You may be interested in an article by John Woodgate titled The Amended EMC Directive. John will be known to many in this group. Direct link http://www.compliance-club.com/article.php?sid=14 You will also find a mass of other information. Cheers Alan E Hutley EMC Compliance Journal nutwoo...@nutwood.eu.com mailto:nutwoo...@nutwood.eu.com
Re: NEC - 1990 version
Gary, I like your Sherlock Holmes hat and pipe! The following is purely my personal opinion based on experience and logic. The NEC wants all electric equipment to have a power disconnecting means. However, they do have to take into consideration certain big equipment (stationary and fixed wiring) that probably may be one of a kind for any particular installation and that will, like my all electric forced air heater, have its own panel with a circuit breaker right next to it. My electric heater is in its own closet. There is a small panel on the wall with a door. Behind the door is a single circuit breaker/overcurrent protection device that is designated for this electric heater. The requirements of the NEC have been met. I agree with Gary that providing equipment without its own disconnecting means is not the best design even if one can get away with it per the National Electric Code. When there is a whole lineup of equipment, and in a panic situation a craftsperson wants to shut off a particular cabinet or rack, looking for the specific wall panel to do so is not the most efficient way to be safe. Install the shut-off device in the equipment and be done with it! Your customer will love you. Tania Grant taniagr...@msn.com - Original Message - From: Gary McInturff Sent: Friday, May 18, 2001 2:54 PM To: EMC-PSTC (E-mail) Subject: NEC - 1990 version I'm trying to make a decision on this issue right at the moment and here is my thoughts so far. Going through this old copy of the NEC index and looking for Disconnecting means I have a couple of interesting options. Electronic computer/data processing equipment, 645-2(1) and 645-10. The first paragraph literally says go to the second paragraph. 645-10 says that a means shall be provided to disconnect power to all electronic equipment in the same roomthey shall be grouped and identified and controlled from locations readily accessible at the principal exit doors. No reference to voltages, although I would assume that they are talking branch circuits. - Tania's note says annex NAB.2 says to treat dc power systems the same. Section 2.3 (UL 1950) allows for a manual statement that requires disconnect device be provided during installation. This matches my experiences with Telecom equipment, that has been accepted and installed. The installations that I have been in have at the top of each equipment rack some sort of power distribution system, that is a series of fuses and/or breakers. They do it for some very practical reasons - there is just a whole lot less chance of the crafts person hitting the wrong switch and bringing down the entire frame. That obviously, would also mean that the craftsperson has less chance of having someone else flip the disconnect back on line while they have their hands inside the equipment. My cynical side says this is only a secondary concern but Further down in this section the NEC refers to sections 705-20 and 705-21 Interconnected electric power production sources. While they don't reference it in the index the next section 705-22 (1) is, in my opinion, very pertinent. 705-20 Disconnecting Means, Sources disconnect all ungrounded conductors 705-21 Disconnecting Means, Equipment from all ungrounded conductors of all sources of supply This would seem to imply having them at both ends !!!?? 705-22 Disconnect device manually or power-operable swtich(es) 705-22(1) Located where accessible. Given the other paragraphs this little modifier looks like a pretty interesting gottcha. I have a couple of interesting locations, tacked onto the outside wall of a building, and on top of a power pole. So this little note convinces me that I will need to provide the disconnect right next to the equipment, and I won't be allowed to rely on the upstream stuff - regardless of a warning in the manual. However, for CO's and NOC's you probably could just put it in the manual. Just ask yourself - beyond the standards allow are you really protecting you users? Gary Please remember that I am using a very old NEC, but I doubt these areas have change much. (The copy I have just has ton's of annotations and page/section markers all carefully put in by the guy I stole this copy from) --- 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 Healddavehe...@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
Re: Public Health and Safety Signs - Tomfoolery so delete if you
Gary, Kudos to you for trying;-- but I think you are confusing your metaphors. And you can't equate logic with brainless juries or judges. And you know better than to rely on warning labels for safety protection! 1. It is assumed that intelligent people will make intelligent choices when opening a bottle with Warning labels that state the content can do you in. 2. It is assumed that a nursing baby, while potentially intelligent, does not have the capability to make any choices whatsoever as to what she is consuming. 3. It is assumed that a lactating mother has a direct effect on the well being of her baby. 4. Therefore, the mother is the responsible party for any adverse effects the baby may suffer due to conditions such as described in 1. above. 5. Therefore, we can assume that any decision rendered otherwise by judge and/or jury is brainless. For technological widgets we bend over backwards to make them safe and we don't rely on labels to protect the general user (trained service persons, however, can be protected by labels in certain cases). However, our legislators/politicians think they can affect and protect our behavior by labels and warning statements.This does not really work;--warning labels are for others, never for ourselves! So, what is the answer? -- Education for intelligent people; and safe design (in case of a single fault, and a subsequent fault) for dumb widgets. Plastering warning labels on breasts will no more eliminate alcoholic babies than plastering warning labels on men's ... will eliminate HIV. Tania Grant taniagr...@msn.com - Original Message - From: Gary McInturff Sent: Friday, May 18, 2001 5:33 PM To: 'Michael Mertinooke'; wo...@sensormatic.com; emc-p...@majordomo.ieee.org Subject: RE: Public Health and Safety Signs - Tomfoolery so delete if you Here in the US, awhile back, a woman was suing the liquor industry because she gave birth to a fetal alcohol syndrome child. Apparently, nobody in their right mind would assume that consuming a fifth of whiskey a day could be harmful to a developing fetus making the liquor industry patiently and damnably negligent in not putting warning labels on the bottles. (We got them now thank God!) During the coverage of the trial, and I don't remember the context, but the issue of passing nastiness to infants who were being breast fed was also brought up. While I didn't hear the end of this I often have wondered that if that was true, and this woman's case had merit (her lawyer took it up didn't he?) then the logical extension would be that mothers milk should come with a warning. Soo Just what the heck will this label look like, and even more importantly, just where are they going to put it so that people, can easily read it! Gary -Original Message- From: Michael Mertinooke [mailto:mertino...@skyskan.com] Sent: Friday, May 18, 2001 12:37 PM To: wo...@sensormatic.com; emc-p...@majordomo.ieee.org Subject: RE: Public Health and Safety Signs signs at work. Is there a similar Directive for health and safety signs for the general public? Whoo! The mind boggles! You mean with like people with exclamation point in triangle tattoos on various portions of the anatomy? Or biohazard labels on the door of the kids' rooms? Judging from some of the ANSI Z535 safety labels I see in the catalogs, the Human Warning Labels would be interesting indeed. =] Cheers! Mike --- 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 Healddavehe...@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 Healddavehe...@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,br clear=allhrGet your FREE
