| 摘要 |
PURPOSE: A power factor discriminator is provided to improve the efficiency of power usage by discriminating a phase difference between voltage and current and determining whether a power factor is capacitive or inductive. CONSTITUTION: An input portion(1) is composed of circuit protection portions(11,12) for protecting circuits from over-voltage and over-current. A zero crossing portion(2) has an OP amplifier including an output side connected directly to a condenser and a diode and an input side connected to both ends of the diode through resistances in order to check a zero crossing point. A sample hold portion(3) has a buffer amplifier including an output side connected to the collector of a transistor and an FET amplifier and a condenser connected with an emitter of the transistor in order to check a phase of a current signal. A comparator(4) compares a zero crossing point of the voltage signal with a phase of the current signal. A micro computer(5) displays a power factor according to a compared value of the comparator.
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