To subject alternating-current input to voltage control or power control to supply a load with the input with reduced alternating current and further prevent erroneous connection of input terminals and output terminals.
A power saving device comprises a current detector 11 which generates alternating current detection signals representing output current supplied from a power regulating portion 4 to a load 2; and a voltage detector 13 which generates alternating- current voltage detection signals representing alternating-current voltage applied from the power regulating portion 4 to the load 2. The power saving device further comprises a multiplier 14 which multiplies an alternating current detection signal by an alternating-current voltage detection signal and outputs a power detection signal representing power supplied to the load; a comparator 15 which compares a power detection signal with a reference value to judge whether the power detection signal is a positive signal or a negative signal, and judges the input/output terminals to be normally connected if the power detection signal is positive and the input/output terminals to be reversely connected if the power detection signal is negative; and a connection display unit 32 which indicates whether the input/output terminals are connected normally or abnormally according to a judgment signal from the comparator 15.
TAKIYAMA HIROYUKI
NISHIZUKA MASARU
SUEKANE KAZUO
SANSHA ELECTRIC MFG CO LTD
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