How to measure the phase angle using a stroboscope?
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I was reading some materials today, and it says that the phase angle can be determined using a stroboscope. Question: How is it determined specifically? I did a search – a stroboscope is itself a high-frequency light source; so how can it determine the phase angle of rotating equipment?
This post was last edited by “The Cat God Who Can’t Be Undone” on February 23, 2016, at 13:16. I’ve never used or even come into contact with a stroboscope for measuring phase angles; however, I guess it operates in the following manner. 1 Attach a scale paper marked with 0-360° to the shaft, then rotate it to collect vibration data; when the vibration level exceeds the set value, the instrument supplies power to the stroboscope, causing its light to turn on ； The stroboscope light turns off when it is below the set value. 2 As the shaft rotates, the previous process is repeated continuously, and the set vibration value is adjusted repeatedly until it reaches its maximum value, at which point the strobe light operates for the shortest time. 3 At this point, observe the axis illuminated by the stroboscope; the value to which the light is directed is the measured phase angle. During this period, the angular position of the stroboscope itself relative to the axis cannot change. If the value observed in step 3 keeps changing, it indicates that the phase angle is unstable. This should be a relatively primitive method, or an alternative when no other option is available.
The phase angle refers to the time difference between a reference point on the axis and the maximum value in the vibration waveform. To measure the phase angle, a reference point must be assumed on the axis, and it is used in conjunction with a vibration meter. This reference point can be a keyway or a reflective strip; its main purpose is to provide a periodic standard pulse. The main function of a stroboscope is to measure rotational speed by adjusting the frequency of the strobe light. When the frequency of the strobe light matches the rotation frequency of the shaft, the position where the strobe light appears remains constant with each rotation of the shaft; this position can be used as a reference point for measuring the phase angle. Once the position of the probe and the stroboscope are fixed, it becomes possible to measure the phase angle.
Maybe just sticking a small piece of reflective tape will do
There’s no need to continue researching it – such primitive methods are far less convenient and user-friendly than modern laser phase measurement techniques, and they are also much cheaper.