Charles, I would like to offer an explanation for EMC limits being set where they are and a reason for meeting or beating the limits. I agree, 0.5 dB doesn't seem like the end of the world and under management guidance/pressure to ship product and produce revenue, it takes a lot of conviction to announce that an additional turn or some tweaking of the design is required.
Those who have ever supplied avionics or anything electric to Boeing have read somewhere in the spec that Boeing guarantees a certain level of performance from the aircraft electrical system. Frequency stability, THC, Voltage tolerance, etc. GREAT NEWS ! think the designers, until later in the spec they read the part about the stringent requirements on the "box" going into the airplane. It seems you can't have clean power without having clean "boxes". The EMC limits in the standards are derived with some exceptions more or less along the limits established long ago by MIL-STD 461/462. These limits are well below where they would create problems in the environment, but allow for the inevitable degradation in product performance that can occur through component value shift, environmental conditions, and other fugitive variables. In order to be able to set limits for Radiated/Conducted susceptibility, an assumption has to be made about the Radiated/Conducted emissions and how much radiated/conducted noise there is in an intended environment. If, "the product works fine" was the criteria for emissions, then the task of hardening products against radiated and conducted energy would become much more difficult. My $0.02 Daniel E. Teninty, P.E. Managing Partner DTEC Associates LLC Streamlining The Compliance Process Advancing New Products To Market http://www.dtec-associates.com (509) 443-0215 (509) 443-0181 fax -----Original Message----- From: Charles Grasso [mailto:[email protected]] Sent: Wednesday, November 28, 2001 9:29 AM To: [email protected]; [email protected] Subject: Re: FW: Quality Assurance and Product Approvals Hi all, I have been following this discussion with great interest and could not resist adding my 2c. Lest face it - EMC is nothing more than pure overhead to any corporation. We all have experience of products that work perfectly fine yet fail the emissions profile by 0.5dB. I will contend that this experience far outweighs the opposite .Spinning a board or adding ferrites or adding shielding does nothing to help our discipline reputation. Couple that with the "twilight zone" impression of EMC and one can easily understand why most companies implement EMC into their process reluctantly. I will add to that one important factor The regulatory bodies - especially the FCC. Thanks in large part to the new FCC Class B compliance procedure ( which inadvertantly allows failing products into the market place) companies are more convinced that ever that EMC is more of an annoyance than a necessity. ( Some exceptions duly noted..) Unlike safety, there is no perceived benefit in squeezing that extra 0.5db out of the emissions profile at a cost od even .03c. The saving grace might be the immunity standards. I have had a whole lot more help when the design engineer actually witnesses his product doing wierd things. NARTE is straying in the direction of elitism. Worse than that they now have professors offering questions for inclusion in the NARTE exam. We need to be vigilant and keep the infulence of the academics to a minimum. Example: The ACES (Applied Computations Society) started a a group with the goal of PRACTICAL applications for comutation ..sound familiar. ?? It wasn't long before the academics (Phds & the like) dominated the group and turned it to a purely theoretical group - a place to publish papers etc.... Now don't get me wrong.I am all for professors that are willing to teach and guide and mentor. There is how ever a human tendancy towards "creeping elegance" and we ned to ensure that the EMC discipline does not tend in that direction. My 2c Charles Grasso Ansoft Corporation >From: "Dan Teninty" <[email protected]> >Reply-To: "Dan Teninty" <[email protected]> >To: "PSTC IEEE-EMC" <[email protected]> >Subject: FW: Quality Assurance and Product Approvals >Date: Tue, 27 Nov 2001 12:11:38 -0800 > > >Rich, > >After sending you my reply, I thought that I would open it up to the group >for comment. I thought I would pass on the information about the NARTE >certification for Product Safety engineers. > >Best regards, > >Dan > >Daniel E. Teninty, P.E. >Managing Partner >DTEC Associates LLC >Streamlining The Compliance Process >Advancing New Products To Market >http://www.dtec-associates.com >(509) 443-0215 >(509) 443-0181 fax > >-----Original Message----- >From: Dan Teninty [mailto:[email protected]] >Sent: Tuesday, November 27, 2001 12:01 PM >To: Rich Nute >Subject: RE: Quality Assurance and Product Approvals > > >Rich, > >I don't disagree with your point of view. It seems that there are a lot of >MBA's devoting allot of time to reducing costs. This is how business is >run. >The days are gone when, like the founders of your organization, companies >could compete on quality, reliability, features, and perceived value. Now >everything boils down to "how can we shave unit cost another $0.03?" >General >Motors has had some high profile cases where this philosophy has led to >injuries and deaths. The world is changing, not always for the better and I >will continue to tilt at windmills. I believe that consumers expect/assume >that products they purchase are "safe" and won't scramble their TV's >picture >during the Super Bowl. Quantifying this perception into a benefit that can >be placed into a spread sheet is, I agree, a difficult if not impossible >task, but a good actuary could probably come up with a defensible number. >The point is that the philosophy of corporate management sets the tone for >the rest of the company and if regulatory compliance is not a priority for >management, then it won't be a priority for the compliance department. >Reducing the amount of flame retardant plastic in a product is commendable >if it doesn't compromise the protection it provides. Engineering is about >trade-offs of conflicting requirements. Integrating compliance into a >product should trade off the risk/consequence of non-compliance leading to >an event. Events lead to lawsuits. I've always made a distinction between >standards requirements and safety. Walt Hart at Fluke was an early mentor >in >product safety and taught me to differentiate between a requirement for a >wire to be blue and a requirement that 5000 Volts not reach an end user. >Harking back to an earlier thread, there are compliance engineers like >yourself who go far beyond the requirements in the standards and understand >the basic principles involved and how this basic science leads to >standards. >Then there are the folks who have compliance thrust upon them and at the >extreme, haven't got a clue. In the commercial world of putting up >buildings and other public structures there is a requirement that a >registered professional engineer review and sign off on drawings. This is >not a perfect solution and there are bad apples, but there is a minimum >level of competence assumed that does not exist in the product safety >world. >EMC engineers have NARTE certification to add to their qualifications and >most of the NARTE certified EMC engineers I've encountered were competent >to >say the least. NARTE has just recently, at the EMC meeting in Montreal, >announced a similar certification for product safety engineers. Some will >say this is an attempt at empire building or elitism, but I contend that >raising the bar will benefit society as a whole and perhaps eventually >elevate the status of compliance engineers from, as we were affectionately >known at Fluke, "Those *&%holes downstairs" to respected professionals. > >My 2 cents, > >Best regards, > >Dan > >Daniel E. Teninty, P.E. >Managing Partner >DTEC Associates LLC >Streamlining The Compliance Process >Advancing New Products To Market >http://www.dtec-associates.com >(509) 443-0215 >(509) 443-0181 fax > >-----Original Message----- >From: Rich Nute [mailto:[email protected]] >Sent: Tuesday, November 27, 2001 10:35 AM >To: [email protected] >Cc: [email protected]; [email protected] >Subject: Re: Quality Assurance and Product Approvals > > > > > >Hi Dan: > > > > Dell Computers, as well as a few other major players, take a proactive > > approach to compliance and actually have a VP position for compliance. >With > > a little investigation into the benefits of having a first rate >compliance > > department with the ability to design for compliance, test to relevant > > standards, compile reports, participate on standards committees, and >deal > > directly with world wide agencies I would think that most companies >that > > have global markets would see both the short term and long term >benefits >to > > the bottom line. I would tend to include PC's into the ordinary >products > > pile, wouldn't you? > >I do agree with (and we practice) a pro-active >approach to compliance. > >In my experience, though, I am surprised that >a compliance manager would be a VP position >(in a company making "ordinary products" as >compared to a company making medical products >or similar products subject to a high degree >of regulation). > >As you mention, there can be short-term and >long-term benefits to the compliance activities >you mention. However, the benefits must outweigh >the costs of the activities. Quantifying and >measuring the benefits of some compliance >activities is often very difficult. > >Management philosophy of the particular company >is another significant variable in the extent >of compliance activity. > >Some companies believe that safety certification >is sufficient safety. Others believe that safety >and safety certification are independent although >overlapping activities. > >At one time, I knew of a company that addressed >safety not in the product, but in liability >avoidance through instruction manuals, through >insurance, and by passing liability on to its >suppliers. Cost effective, yes. Morally >effective, questionable. > > > Companies that choose to take the adversarial approach to compliance >by > > cutting corners or only doing the minimum to comply, save dollars in >the > > short term, but pay later in lost customers, or worse, lawsuits. One >of >our > > clients, had a management team that took this denial/avoidance >approach >to > > NEBS. When the Telecom downturn came, they were left in a position >where > > there was lots less demand and what demand there was, was for NEBS >compliant > > products. Most of the management team that made those decisions have >either > > left the company in recent right-sizing exercises, or are working in >lesser > > positions. > >Reducing the cost of compliance does not in any >way imply an adversarial approach to compliance. >Neither does cost reduction imply a reduction in >the compliance performance of the product. > >For example, some years ago a R&D engineer came >to me and said, "The cost of safety is too high." > >My immediate response was, "Not if you design in >safety from the start of the project." > >He replied, "No. I mean that safety requires me >to use a power switch and a fuse. These cost >money. The switch serves no benefit to the user >since the unit is left on continuously." (This >was back in the days when the plug was not >considered a disconnect device.) > >So, I started a project to determine alternatives >to switches and fuses and other safety components >(for the specific products we were building at >that time). > >In terms of EMC compliance, I know one engineer >who keeps track of the number and cost of components >used exclusively for EMC control. His objective >was to reduce the total cost of EMC control. This >in no way is cutting corners of compliance, or >doing the minimum to comply. The result was still >full compliance -- but at least cost. > > > It seems that hindsight is always able to find a goat. When I explain >the > > benefits of compliance to management teams, I try to focus on the >bottom > > line benefits of having a product that is marketable everywhere. The >costs > > for compliance, when compared to the total development cost for a new > > product tend to be in the noise. If these costs are amortized over > > reasonable quantities, then the unit cost for compliance tends to be a > > bargain. > >There are two kinds of costs associated with >compliance. > >The first kind is the cost of compliance in the >product development. I agree that these costs >are indeed "in the noise" compared to the overall >development costs. > >The second kind of cost of compliance is the cost >of labor and components that are installed solely >for compliance. For high-volume products, these >costs are far more important than the costs of >development because they affect the price >competitiveness of the product. A flame-retardant >plastic costs more than a non-flame-retardant >plastic. How can we design a product to minimize >the use of flame-retardant plastic yet comply with >the standards as well as being a truly safe product? > >For me, this second cost, the per-unit cost of >compliance, is a very significant part of my job. > > >Best regards, >Rich > > > > >------------------------------------------- >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: > [email protected] >with the single line: > unsubscribe emc-pstc > >For help, send mail to the list administrators: > Michael Garretson: [email protected] > Dave Heald [email protected] > >For policy questions, send mail to: > Richard Nute: [email protected] > Jim Bacher: [email protected] > >All emc-pstc postings are archived and searchable on the web at: > No longer online until our new server is brought online and the old >messages are imported into the new server. _________________________________________________________________ Get your FREE download of MSN Explorer at http://explorer.msn.com/intl.asp ------------------------------------------- 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: [email protected] with the single line: unsubscribe emc-pstc For help, send mail to the list administrators: Michael Garretson: [email protected] Dave Heald [email protected] For policy questions, send mail to: Richard Nute: [email protected] Jim Bacher: [email protected] All emc-pstc postings are archived and searchable on the web at: No longer online until our new server is brought online and the old messages are imported into the new server.
