Conformity Magazine - November 2007 - (Page 57)

Resistance, and are often referred to as 5-in-1 or 6-in-1 testers. If purchasing a multi-functional tester, ensure the tester can handle the current needed to power the product. Some products such as fans, blenders and larger medical systems have a large in-rush current. Check with the manufacturer that their product can handle the load. Isolation transformers are frequently required by the safety standard, and by the test equipment manufacturer. Isolation transformers isolate the power to the product being tested so that an accurate leakage measurement can be made. Be certain the isolation transformer can also handle the power requirements of the product. Features Within a Hipot Tester Aside from the older analog testers, any Hipot tester on the market should have a digital display, not only for ease of use but to reduce operator error (by misreading an analog dial). One reason for the “high tech” Hipot is the rarity of skilled operators. The demand increases for the test equipment to incorporate safety features that prevent improper testing. Programmable test limits, keypad lockout and program memory are necessary features. New testers allow for multiple tests (with different limits) to be stored in memory. Once the test conditions have been stored, the panel can be locked out, another safeguard against incorrect parameter testing. Safeguarding the product and test data is important, however safeguarding the operator is of the utmost importance. High voltage and current are output from these testers; therefore safety precautions should be put in place to prevent the risk of injury. A properly trained operator will reduce risk; however accidents do happen so Hipot manufacturers have implemented additional safety features. Look for features such as interlock, GFI, fast DUT discharge, and quick HV shutdown. Interlocks are usually a mechanical method of stopping the tester if open. Interlocks may be connected to a light curtain located around the tester. If someone interrupts the light beam, the tester will shut down. Palm switches are another common form of interlock, which forces the user to keep his hands on the switches and away from the tester at all times. When the users hands are removed from the switches, the tester stops. Extreme forms of interlock have been used such as placing the tester in a room, once the door is shut the tester can run, if the door opens the tester will stop. In Europe these extremes are common and required per EN50950 if the tester can output more than 3mA of current. Some hipot testers limit their current to 3mA to meet this standards requirement. If using an interlock, the tester should have a quick shutdown. There is no purpose in installing an elaborate interlock system if the tester does not shut down quickly. Additional safeguards are being implemented in the newer testers. GFI, Ground Fault Interrupt can now be found in most new testers. There are different variations of GFI on the market for hipot testers, but they generally serve the same function. If the current flowing out of the tester (iout) does NOVEMBER 2007 CONfORMity 57 http://www.kikusui.us http://www.kikusui.us

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

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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