Instrumentation to test the safety of electrical installations, appliances, machines and electrical/electronic devices is becoming more prevalent, driven by new regulatory standards designed to protect users from electrocution and fire hazards. Examples of mandatory, annual testing standards are the UK BS 7671/16th Edition and the German equivalent, VDE 0100. Both ensure safety compliance in commercial and residential electrical installations. Other standards, like EN 60601/60335/60950/61010 and VDE 0700, are designed to ensure the safety of electrical appliances and machines. Other types of safety compliance testing are done in the final stages of electronic device manufacturing to ensure product safety and robustness, to comply with standards like CE. As these standards have become mandatory in numerous countries throughout the world, electrical safety tests are becoming commonplace as test specialists, technicians and production engineers need to demonstrate that installations, appliances and devices conform to strict government or test body standards. The instrumentation used to make these tests fall into a number of categories: Insulation Resistance testers, Installation testers, Portable Appliance Testers (PATs), Earth Resistance testers, Ground Bond testers, HiPot testers and Electrical Safety Analyzers. They are used in a variety of applications and industries, from electrical appliance manufacturers, to electricians, contractors, hotels, hospitals, aerospace companies, plant maintenance, and so on. In the past, it has been a challenge for metrologists to properly verify electrical testers' performance, especially for those testers with high voltages, high currents and extreme resistance measurement capability. This paper describes the functionality of some of the electrical testers, and discusses requirements to verify their performance. It will also cover an improved method of verifying many of these devices and the challenges the design engineers faced when building these techniques into a new calibrator.
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