Applicable to associated power transformers for switch mode power supplies, single-phase or poly-phase, air-cooled: separating transformers; isolating transformers; safety isolating transformers having a rated supply voltage not exceeding 1000 V and a rated frequency of 500 Hz to 1 MHz, the rated output not exceeding: 10 kVA for single-phase transformers; 16 kVA for poly-phase transformers.