Issue with the unit vibration range
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A Bentley probe for use in engines, combined with an extension cable and a pre-amplifier. The range on the DCS is 0-150um. I just wanted to ask, isn’t everything within the range of -150 to 150? The range of displacement is from negative to positive. So the vibration doesn’t start at a negative value? Vibration is generally installed at the top. When installing the vibration probe, 10V corresponds to a gap of 1.27 mm; when the gap is less than 1.27 mm, the DCS displays 0, and it is only when the gap is greater than 1.27 mm that the DCS shows a value. If the DCS shows 0 during installation, can the gap not be determined? Or maybe the shaft of the unit has moved upward as a whole, getting closer to the probe – in fact, it’s now quite close to the probe. The DCS keeps showing a value of 0; could this cause the shaft to wear against the probe, making it impossible to take measurements?
As I understand it, the vibration of the device and the distance of movement in the axial direction are two different concepts. It is recommended to check the concepts and units of measurement for “vibration” and “distance”.
Agree with the second floor’s view; imagine the concepts of vibration and displacement. Vibration refers to the radial variation of the axis, and the probe measures the peak-to-peak value of the alternating signal, which is 0 when at rest； Displacement measures the axial change; the probe detects the DC value of the signal. Ideally, the shaft is in the middle position within the allowable range of movement, which results in positive and negative values.
Displacement can be positive or negative, but how can vibration have a negative value?
Unit vibration and displacement are two different parameters; vibration measurement refers to the maximum value deviating from the static zero point, and it only concerns the maximum level of vibration. Displacement detects the axial displacement of the shaft; it has a direction with respect to the static zero point, which makes it easier to identify unit failures.