Conformity Magazine - October 2007 - (Page 40)

While the reference electromagnetic interference filter offered a significant improvement over UL 1449 suppressors, the total surge cancellation electromagnetic interference filters had less than a 10 volt surge voltage let-through lasting only 2 microseconds for dangerous surge input levels. Oscillograms of voltage responses at 4,000 volts, 2,000 amps and 6,000 volts, 3,000 amps are shown in Figure 3 and Figure 4. In essence, all the surges applied to the total surge cancellation electromagnetic interference filters were kept within the normal 120 volt ac voltage variations, and any downstream equipment would have been unaffected by any surge. UL 1449 or UL 1283 Safety Listing? Both UL 1449 and UL 1283 are safety standards. The safety testing in both documents is similar where wire sizes, temperature rating of components, allowable temperature rise, exposure to anticipated failure modes, etc. are concerned. However, a principle difference between UL 1283 and UL 1449 occurs when tests are applied which evaluate clamping components such as MOVs. These tests are very specific to the components that are representative of the dominant technologies used in the marketplace. While UL 1449 Third Edition will be the prevailing standard for surge protection devices, certain filters with a UL 1283 Listing may be more effective at removing dangerous surge voltage from protected equipment. The core technology behind some of these filters has a proven long-life expectancy, and such devices can remove both the surge danger and associated noise. Therefore, where vital or sensitive equipment needs the best available protection from surges and noise, such total surge cancellation electromagnetic interference filters may be a better choice than the conventional UL 1449 Listed products. J. Rudy Harford is Chief Engineer at Zero Surge, and can be reached at rharford@zerosurge.com. Figure 3: Total surge cancellation response to 4KV, 2KA surge Figure 2: Baseline response to 4KV, 2KA surge Note: The filter described in this article is protected by U.S. Patents: 4,870,528, 4,870,534, 6,728,089, 7,068,487 and 7,184,252. FAST Link www.conformity.com/1060 Figure 4: Total surge cancellation response to 6KV, 3KA surge 40 Conformity oCtober 2007 http://www.conformity.com/1060

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

Contents Editor’s Note Commission Proposes Changes for 57-64 GHz Spectrum Rules FCC Continues Actions Against Jamming Device Distributors Radio Operator Fined for Failing to Make Equipment Available for Inspection Commission Fines Unsolicited Fax Advertisers Firm Offering Quality Standards Training Also Fined Breaking New Ground with Lithium-Battery Generic Requirements for Use in Telecommunications Facilities ESD Open Forum EMC UK 2007 Conference Set Staying Abreast of U.S. E-Waste Legislation EU Commission Establishes RFID Expert Group Update on China's CCC Compliance Program System Level ESD Testing: The Waveforms An Alternative Approach to Surge Suppression Testing Equipment Buyer's Guide EU Scientific Committee Releases Updated Data on EMF Risks Updated Standards List For The EU’s EMC Directive Updated Standards List For The EU’s Directives on Measuring Instruments Call for Presentations for 2008 International ESD Workshop Announced CPSC Actions In The News IEC Standards Update Product Reviews UL Standards Update New Products From Our “You Can’t Make This Stuff Up” Department Looking Back: Items from Past Issues of Conformity Upcoming Events Advertisers

Conformity Magazine - October 2007

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