Slow-Roll Reference Calibration

Imperfections on a device under test can result in distortion or unwanted signals in order analysis applications. These imperfections affect the accuracy of proximity probe signals. A proximity probe measures the distance between the probe tip and the shaft surface. Because of the existence of shaft scratches, shaft bow, and variation in electrical properties, the shaft imperfections and resulting unwanted signals distort the vibration signals of interest. When this occurs, perform slow-roll compensation. In slow-roll compensation, you collect a reference signal by setting the shaft to rotate at a low speed. This reference signal is called the slow-roll reference signal. You then subtract the reference signal from the signal you acquire during normal operation to remove imperfection errors. The slow-roll speed is typically less than 10 percent of the first resonance speed.