Importance

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Abstract

A circuit is disclosed for measuring reactive energy or reactive power. The circuit comprises a main multiplier, a signal/frequency converter, and a frequency divider all connected in series to form a cascade circuit having an output connected to a display. A 90.degree. phase shifter has an input for receiving a first signal component (e.g., alternating voltage) of the reactive energy or power. A second signal component (e.g., alternating current) is connected to a second input of the main multiplier. The phase shifter has a frequency dependent transfer function K[f]. In order to eliminate the effect of this transfer function on the measurement of reactive power or reactive energy, the arrangement includes a frequency measurement circuit for measuring the frequency of the first signal component and a frequency/signal converter for generating an output signal dependent on K[f]. The output signal of the frequency/signal converter is connected to an input of the cascade circuit so that the frequency dependence of the phase shifter is eliminated from the output of the cascade circuit.

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First Claim