This Standard applies to single-phase or polyphase, air-cooled (natural or forced) portable inverters having a rated supply voltage not exceeding 60V ripple-free d.c. and an alternating current (a.c.) output where: - the rated output does not exceed 3kVA; - the rated output voltage is within the range 50 - 500 volt a.c; - the rated frequency of the output is within the range 40 - 100Hz.