sTEm–at-Work Puzzle #55: Signal Analysis for a Capacitance Manometer

A mechatronics tech working in the trace (space outside of the clean space) of a clean room is dealing with a vacuum pump capacitance manometer. The Tech has access to the documentation package for this vacuum system. That information indicates that a pressure gauge that uses a capacitor based sensor will shift the current signal out of phase with the voltage signal and that the current signal is expected to lead the voltage signal. The Tech knows the pressure measurement in the vacuum chamber changes the voltage and current values in the electric circuit of the vacuum chamber gauge because the chamber pressure changes the capacitance of the sensor in that gauge's circuit. The two AC signals shown below indicate the gage signals the Tech sees on an oscilloscope when trouble shooting this system.  The Plot Legends indicate that the red dotted curve represents the current, and the blue curve is the voltage signal.  For this specific situation, the values reflect a constant pressure situation in the chamber.    



Question

Do the two plots below represent what the technician might expect to see in this constant pressure situation?  YES or NO Submit your answers below the blog post, or at www.fl-ate.org.