Conformity Magazine - August 2008 - (Page 28)

target for current measurement illustrated in the latest version of the standard. While both targets may be manufactured by a test service for their own use, I would expect some test equipment providers may wish to supply these additional calibration targets for test laboratory use to support the new standard, once it has been released. The targets give a very quick and easy way to do routine calibration prior to testing, and the 2Ω target certainly looks like a more repeatable solution than some of the sparkgap targets I have seen used. This calibration information represents 16 pages of the new edition, and represents a significant addition in terms of the document size, despite its relatively low impact on the testing itself. These targets could also be used to prove that 5% accuracy is being achieved for existing test equipment. ESD Testing Stress Step Testing This was always implied in the current edition of the standard, suggesting testing at all levels up to the maximum. In the new edition of ISO 10605, this is specified as testing at a minimum of two severity levels before the maximum is applied, a slightly more pragmatic approach. Time Between and Number of Discharges The minimum number of discharges remains the same for direct (contact) discharge at three per test point of both polarities. The minimum time between direct discharges has been reduced to 1s from 5s and this should speed up testing. However, a producer can specify a longer time between discharges if they feel this is required to allow charge to dissipate. The indirect (air) discharge minimum number is now specified as 50, whereas the current standard applied the minimum 3 to both discharge methods. This is for each test point and polarity again, but time between discharges is reduced to anything above 50ms. The total test time is most likely going to be significantly increased still, as it is unlikely many ESD generators can discharge high voltages at these recovery rates and, because this high rate of discharge has no basis in simulating the reality of an air discharge, it is potentially unfair to the product. The premise for this increase is to improve repeatability, but surely a lower number (e.g., 10) would have been adequate, and forcing a fixed holding arrangement and discharge distance would be more consistent than simply increasing statistical probability. If anything, I would expect having 50 pulses would probably reduce repeatability while increasing the risk of product failure in an unrealistic test. As a consequence of these changes, I would expect total test time under the updated standard to double when compared to testing to the current edition. Test Cases There are still three test cases: handling of the ESA (or unpowered ESA test), powered ESA, and on-vehicle testing. Figure 1: New optional test to simulate the in-vehicle discharges close to the harness 28 Conformity AUGUSt 2008

Table of Contents Feed for the Digital Edition of Conformity Magazine - August 2008

Conformity Magazine - August 2008 Contents Editor’s Note FCC Seeks Comment on Reauction of 700 MHz D Block Commission Cracks Down (Again!) on Junk Fax Marketer Canada Levies Fees for Public Safety Radio Spectrum FDA Issues Guidance on Medical Device Tracking Greenpeace Challenges Video Game Manufacturers The IEEE EMC Society: A Proud History of Accomplishments ESD Open Forum An Update on Changes to the Automotive ESD Standard, ISO 10605 Modeling of Radiated Electromagnetic Disturbances in Automotive Applications Design Issues in Automotive Radio Frequency Systems IEEE EMC Symposium IEEE 2008 Show Preview Exhibitors Buyer’s Guide Product News Most Eco-Friendly Companies Updated Standards List For the EU’s Pressure Equipment Directive Commission Issues Updated Standards List For Directive on Gas-Fired Appliances HHS Releases Fact Sheet on U.S. Imports from China Customs Agents Seize Holiday Lights IEEE PSES Symposium Set for October CPSC Actions in the News IEC Standards Update UL Standards Update Telcordia Standards Update From Our “You Can’t Make This Stuff Up” Department Looking Back: Items from Past Issues of Conformity Product Reviews Advertisers

Conformity Magazine - August 2008

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