Performance indicator for compressor analogs

Claim 1

A performance measuring device for use with an electrical analog of a reciprocating compressor, comprising: a digital output device for presenting digital output data indicative of the performance of an electrical analog of a reciprocating compressor; phase measurement means coupled to said digital output device for measuring the phase relationship between a non-sinusoidal driving signal and a sinusoidal reference voltage, said phase measurement means comprising: means for generating first and second consecutive pulses, wherein the pulses exist while the driving signal voltage is higher than a first calibrating voltage, and wherein the first pulse ends and the second pulse begins when the reference signal crosses a second calibrating voltage on a positive transition; means for adjusting the relative phase between the driving and reference signals; means for determining when the first and second pulses have the same width; means for generating a third pulse having a width proportional to the phase difference between the reference and driving signals; means for indicating the width of the third pulse; means for adjusting said indicating means to read 90° when the first and second pulses have equal width; horsepower measurement means coupled to said digital output device for measuring changes in output horsepower of the electrical analog of a reciprocating compressor from a preselected ideal level; and current measuring means coupled to said digital output device for measuring the change in steady state current discharged from said electrical analog of a reciprocating compressor.