Despite these shortcomings, showering arc testing is neces-sary. The nature of arcing switches on inductive loads in high-power utility settings is always somewhat unpredictable. A real-world power-switching setting is very noisy and random. It is recognized as a mixture of fast-rise-time repetitive and oscillatory events. This could certainly describe the threats delivered by the showering arc generators and coupler shown in Annex E. Power and industrial control customers will continue to use the NEMAICS 1-2000 standard as a benchmark or figure of merit for the equipment they purchase. Manufacturers want to sell equipment into the growing power market, and showering arc testing to NEMA ICS 1 -2000 will be required to succeed. The availability of commercially built test equipment for this standard has improved, and a number of laboratories provide showering arc testing. In the United States, many products sold to the power industry are currently tested for showering arc immunity to repetitive and oscillatory threats. In Europe, tests to address these threats are specified in the EMC product standards IEC 60255-22-4 (burst or single polarity) and IEC 60255-22-1 (1 MHz ring-wave or oscillatory). The standards specify measuring relays and protection equipment. It is clear that utility products bound for either market will require testing for immunity to these threats.
展开▼
