Vibration Phase Reference for Rotating Shaft
Vibration Phase Reference for Rotating Shaft
(OP)
Hello,
I was curious what provisions (if any) are usually provided in rotating industrial machines to use as a phase reference for condition monitoring. One example would be a keyway or notch in the shaft for a proximity sensor. Is it common for manufacturers of rotating equipment to provide provisions for this in the design, or is it usually just up to the technicians who are balancing to figure out how to get a phase reference? (Using an optical sensor and reflective tape, for example) What way do you guys find to be the easiest, and what methods are most commonly used?
Thanks!
I was curious what provisions (if any) are usually provided in rotating industrial machines to use as a phase reference for condition monitoring. One example would be a keyway or notch in the shaft for a proximity sensor. Is it common for manufacturers of rotating equipment to provide provisions for this in the design, or is it usually just up to the technicians who are balancing to figure out how to get a phase reference? (Using an optical sensor and reflective tape, for example) What way do you guys find to be the easiest, and what methods are most commonly used?
Thanks!





RE: Vibration Phase Reference for Rotating Shaft
If we want to do phase analysis on a machine that is not equipped with a keyphasor®, then we have a few options. Many of our machines run constantly and cannot be shut down to allow for the addition of reflective tape. In those cases, we can use a two-channel analyzer. One probe is fixed and set to lock in on the run speed peak as the reference. The other probe is used to rove around to all the other points providing a phase reference back to the run-speed peak on the fixed probe. We have also used a laser tach looking at a keyway, installed with the machine running as the phase reference.
If we have the luxury of shutting the machine down, we can install reflective tape and use a tachometer as the phase trigger.
If you are building a new machine, I would suggest drilling appropriate target dimples into each shaft to allow for phase angle reference probes. If you are planning to use the phase reference for field balancing, then you can shut the machine down to add the target and use a proximity probe on a mag base mount.
Johnny Pellin
RE: Vibration Phase Reference for Rotating Shaft
Cheers
Greg Locock
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RE: Vibration Phase Reference for Rotating Shaft
Also, is it better to just drill a hole or divet in the shaft as opposed to a keyway, assuming its at an unloaded end of the shaft? Machining is certainly easier, but is there an advantage to One or the other?
RE: Vibration Phase Reference for Rotating Shaft
Johnny Pellin
RE: Vibration Phase Reference for Rotating Shaft