fuse protector - soft start for high-current equipment

fuse protector elektor february 1 983 soft start for high-current equipment H. Dominik The rating of the new power amplifier is "350 VA max.". Thus the maximum power consumption of the amplifier is 350 watts. Since the circuit breaker is rated at 16 A, why does it trip each time the amplifier is switched on? The paradox seems to contradict Ohm"s Law; when connected to the 220 V mains, our amplifier with its 350 watt rating should not draw more than 1.6 A — a tenth of the value required to trip the circuit breaker. Something is wrong: is it our arithmetic, the circuit breaker or the ratings indicated on the amplifier? Initial current surge Incandescent bulbs have a so-called cold resistance. This means that the filament material exhibits a positive temperature characteristic. The resistance of a bulb filament at room temperature is only a fraction of that at its operating temperature, about one seventh of the normal resistance. Clearly, it only takes a 500 W lamp to trip the circ...