When sensors are pointed at a keyway on a shaft to measure RPM, what is this called?

When sensors are pointed at a keyway on a shaft to measure RPM, it is referred to as a key phasor. The key phasor serves as a specific point of reference that assists in synchronizing the measurement of rotational speed and allows for accurate vibration analysis. By identifying the rotational position of the shaft through the keyway, the system can determine the phase relationship of vibration signals in relation to the rotational position.

This technique is crucial in vibration analysis because it helps in analyzing frequency components and identifying potential issues within the machinery. The keyway provides a consistent and repeatable reference point for these measurements, which is essential for diagnosing mechanical problems and ensuring proper maintenance.

While terms like "speed sensor" or "phase marker" are related to measuring rotation or timing, they do not specifically identify the context of using a keyway as a reference point; thus, they are not as precise as "key phasor."