Fluke 831 User Manual page 69

Number of points – The higher the number of measurement points taken, the better the
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effect on the quality factor. The measurement points should be spread over as wide a
rotational angle as possible.
Rotation angle – The wider the rotational angle through which the shafts and/or coup-
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lings are rotated during measurement, the better the effect on the quality factor.
Point standard deviation – For every measurement point, a number of readings are
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taken depending on the set averaging. Point standard deviation is the root mean square
deviation of these readings.
Ellipse standard deviation – This is the root mean square deviation of the measurement
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points on the calculated ellipse.
Equal point distribution – In point measurements, it is advisable to take measurements
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at equal angular steps, say 0°, 45°, 90°, 135°.
Environmental vibration – the level of external vibration e.g. from neighbouring running
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machine(s)
Rotation evenness – the smoothness of the measurement rotation e.g. if there is any fric-
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tion during the rotation that 'jerks' the shaft
Angle rotation inertia – abrupt changes in the measurement rotation speed e.g. releas-
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ing and re-applying a break during the rotation
Rotation direction – change in the measurement rotational direction
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Rotational speed – how fast the sensor and/or shaft is rotated during measurement
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Filter output – the amount of measurement data filtered out
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