Conformity Magazine - November 2007 - (Page 56)

Continuity because it may detect a problem in the ground circuit that the continuity test may not. The ground bond test applies high current, usually 25 – 40 Amps, to the same ground path as the continuity test. The resistance of the ground path, normally less than 100 mW is measured using a Kelvin connection. Not only does ground bond verify the continuity but it verifies the integrity of the circuit and its ability to carry high current. There are a number of testers that combine hipot and ground bond. Many test manufacturers create a combo pack in which the hipot tester and ground bond tester are connected; one connection to the device under test is required, and the test is initiated at the ground bond tester. Once the ground bond test passes, the hipot will start automatically. Other testers combine both tests in one piece of test equipment. Whether you purchase a combo pack or an all-in-one unit, ensure that the tester can handle the current output and resistance measurement required. An Insulation Resistance measurement is similar to a DC hipot test except that it measures the total resistance between any two points separated by electrical insulation rather than the leakage current between these points. Insulation resistance tests are typically performed at a lower voltage than DC hipot tests. When choosing a tester to perform Insulation resistance measurements, check the measurement range of the tester. Most hipot testers can measure up to 50GW, but sometimes standards may call for a higher resistance than the tester can handle. If this is the case then a megohmmeter may be necessary. There are multiple leakage current tests that can be specified by product safety standards. The most common is the Line (Earth) Leakage Current test. The line leakage test measures current flow from the AC line source through the ground path of the product while under normal operating conditions. Variations of this test are Patient Applied Part Leakage, Patient Auxiliary Leakage, and Touch/Chassis (Enclosure) Leakage. All of these tests are performed by powering the product and measuring the leakage through a circuit that simulates the human body, known as a human body model. Line leakage tests are typically a design test on non-medical devices and a production test on medical devices. A very similar test requirement is Power Consumption, common in the IT and appliance industries. Just as it sounds, power consumption measures the power being used while the product is running and while it is in standby mode. With all the personal (and commercial) electronic devices in use today, standby mode power consumption is a concern. Limits for standby power consumption of household electrical appliances are addressed in IEC 62301. Higher-end hipot testers perform most or all of the line leakage tests as well as Ground Bond, Hipot and Insulation Another Step Forward View every page of Conformity magazine digitally. That includes every article, every NewsBreak, every ad, everything you’ve come to expect from Conformity, The Integrated Authority on EMC Compliance and Design. � View every page of Conformity as it appears in print. View advertisers’ web sites with one click. Print pages. Save an offline version to your desktop. Send the digital issue to a friend via e-mail. READERS: Sign up to receive your digital edition at www.conformity.com. ADVERTISERS: To participate in the digital edition call 978-486-0888 56 Conformity noVEmBEr 2007 � � � � www.conformity.com http://www.conformity.com http://www.conformity.com

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Conformity - November 2007 Contents Editor’s Note Commission Sets Date, Terms for 700 MHz Auction FCC Reaffirms Roaming Obligations Commission Moves to Improve USF Management FCC Proposes Fines for Violations of E911 Handset Requirements Commission Levies $1 Million Plus Fines for Unsolicited Fax Advertisements GR-3150 - Lithium Battery Certification Levels Based on Criteria for General Product, Safety, and Performance, Part 2 ESD Open Forum Machinery Field Evaluation for the United States Validation, Verification, and Immunity Testing Techniques for EMC for Functional Safety Thermal/EMC Simulation Addresses New Mechanical Design Challenges Product Safety Equipment Buyer’s Guide FCC Releases Report on Telephone Numbering Resource Utilization Canada Still Has PCS Spectrum to Assign Updated Standards List for the EU’s Medical Devices Directive Updated Standards List for EU Directive on Active Implantable Medical Devices Call for Papers for the 2008 EOS/ESD Symposium Announced Mobile Phone Use in Hospitals May Be Dangerous CPSC Actions in the News IEC Standards Update UL Standards Update Telcordia Standards Update From Our “You Can’t Make This Stuff Up” Department Product Reviews Looking Back: Items from Past Issues of Conformity Upcoming Events Advertisers

Conformity Magazine - November 2007

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