A New Wave-Shape Factor and Meter

A star-connected circuit consisting of two voltmeters and one variable condenser has certain properties upon which a wave-shape factor may be based. When the voltmeter resistances are equal to each other and equal to the condenser reactance, the ratio of the voltmeter readings will always be (2 + ??3) for an alternator producing sine waves and always less than (2 + ??3) for all other wave shapes. From any measured ratio of voltmeter readings, the purity of the voltage wave may be determined; furthermore, the maximum possible percentage of any single harmonic present in the wave can be immediately obtained (See Table III). For the experimental application of this method a wave shape meter is proposed for practical application which consists essentially of two voltmeters and a variable condenser. Such a meter has advantages over the method of analysis based on oscillograms, namely: (1) cost, (2) portability, (3) ease of experimental procedure and (4) rapidity of arriving at results. This method of attack is not intended to supplant the oscillograph but rather to supplement it. The method has been checked with the aid of a harmonic alternator and has been applied to the local power system and to various alternators available in the Electrical Engineering laboratories of the Pennsylvania State College.