DIRECT READING DEVICE FOR HIGHER ORDER HARMONIC WAVE

PURPOSE:To make digital display possible by separating input voltage from a power transmit ting and distributing end into fundamental wave component, higher order harmonic wave component and each order harmonic component and calculating distortion rate and content of each order harmonic wave of input voltage from their effective values. CONSTITUTION:Input voltage from a power transmitting and distributing end is divided by an input voltage divider 1, and signal voltage from the voltage divider 1 is separated into fundamental wave voltage component and higher order harmonic wave component other than fundamental wave by a BPF 2. The fundamental wave component voltage is converted to an effective value by an RMS/DC converter 3 and compared 4 with reference voltage generated in a reference voltage generating section 5, and gain adjusted to make effective value of fundamental wave component voltage at the output end of an amplifier 6 always a fixed value. The distortion rate is calculated from the fundamental wave voltage effective value and higher order harmonic wave voltage effective value at output end of the amplifier 6. Then, the higher order harmonic wave voltage component is separated into respective band frequency signals by plural BPF 11-13 of different band frequency and a change-over switch 14, and then converted to effective value by an RMS/DC converter 9. Content of n-order harmonic wave is calculated from effective values of these components and displayed digitally.