Dear all, Still trying to understand 60950-1. How to limit power source to 15VA (Cl. 4.7.2.2) ? A circuit powered from 12V (5A) source takes only 0.1A. Do inserting one 0.1A PTC (or fuse) between source and circuit is enough. When PTC is shorted the circuit takes 0.1A, when circuit has error the PTC limits current to 0.1A. But when PTC is shorted the sentence: "circuit is supplied by power source which is limited to 15VA" is not true. So I suppose two PTC in series are needed. Am I right ? If one PTC is not enough, I suppose one PTC and 7805 (5V regulator with internal current limiting) are enough. The 7805 is not powered by power source limited to 15VA, but any circuits after it are. Am I right ? Best Regards Piotr Galka
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