Conformity Magazine - September 2007 - (Page 27)

The first CD [3] included proposals to change the ESD generator, the metrology for calibrating the generator, and the test setup. Of these proposals, the one that received the most reaction was the changes to the test generator. It called for keeping the basic shape of the discharge current and specified parameters shown in Table 1, and adding a tolerance of ±35% around the current waveform. The tolerance band was intended to reduce high frequency content on the current waveform. The hypothesis driving this change was that the unwanted high frequency energy is the source of some of the test result reproducibility problems, and that reducing it would improve reproducibility, especially when using different make and model test generators on a single EUT. It was hoped that including this proposal in the CD would generate comments and useful data. It turned out that most commercially-available test generators would not meet the ±35% tolerance band. Hence, nearly all existing test generators would have to be modified or replaced. This information was very useful to the IEC, and was the impetus for a “round robin” test subsequently performed in the second half of 2006. The purpose of the round robin was to determine quantitatively if cleaning up the discharge current would improve the reproducibility of test results. If it did, then pursuing this change would be the right thing to do. If it did not, then the added expense of modifying or replacing existing test generators would not be justified. With assistance form the test equipment manufacturers participating in MT12, a revised discharge current specification that reduced high frequency content and was manufacturable was developed. Prototype test generators meeting this specification were provided for the round robin. Figure 1: Approximate discharge current waveshape September 2007 Conformity 27 http://www.ProductSafeT.com http://www.ProductSafeT.com

Table of Contents Feed for the Digital Edition of Conformity Magazine - September 2007

Contents Editor’s Note FCC Extends Disability Access Requirements to VOIP Commission Fines Importer $3 Million Over Non-Compliant TVs FCC Gets Tough on Retailers Over Analog TV Tuner Labeling Analog Cellular Service Sunset Date Reaffirmed Commission Adopts Recommendations of Katrina Panel Free-Space Antenna Factors Through the Use of Time-Domain Signal Processing Editorial Correction ESD Open Forum An Update on Revisions to IEC 61000-4-2, the Basic Standard on ESD Practical Advice for Meeting the DFS Testing Requirements of the FCC The EMC Impact of Embedded Software ESD Design Buyer's Guide Tate Renominated to the FCC EPA Releases Report on U.S. Electronic Waste Additional Standards For The EU’s Toy Directive Medical Device Manufacturer Enters Consent Order Updated Guidance Document on Laser Products Issued FDA Offers Advice on Defective Heating Pads CPSC Issues China Product Safety Program Report Other CPSC Actions In The News IEC Standards Update Product Reviews Product News UL Standards Update From Our “You Can’t Make This Stuff Up” Department Looking Back: Items from Past Issues of Conformity Advertisers

Conformity Magazine - September 2007

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