sTEm–at-Work Puzzle #54: Signal Analysis for a Resistance based Temperature Sensor

A Mechatronics Tech has a strong background in electrical circuits and knows what to expect when AC signals are used to measure sensor response data, or send signals to control a motor. The illustration below shows the typical practice of presenting three different AC signal forms related to the sensor performance on the same time axis. The Tech knows that one period of each of these sine wave signals is 4 seconds. The Plot Legends indicate that the red dotted curve represents the current and the blue curve in the middle is the voltage signal. The Tech knows that the top purple curve could represent the power calculation for the voltage and current signals shown. The Tech also knows that a specific power value is the product of the current and voltage value at that specified time. In the specific situation below, the Tech knows that the three plots are in phase; the current measured values are identical to the value of applied current (values not shown) through the sensor; the current and voltage values are positive between 10:01:01 AM and 10:01:03 AM; and the temperature changes if the sensor's resistance value changes. Therefore, the Tech also knows that in this situation, the temperature being monitored is constant. 

Do the three plots below represent what the Technician expects to see in this constant temperature situation? Yes or NO

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