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Under Range & Overload Conditions
Under Range Condition
An under range condition occurs when the vibration level is equal to, or lower
than the bottom of the current range the meter is set to. If this condition
occurs then the Under Range indicator will be displayed on your instrument. In
such circumstances it is highly recommended to change to a lower range with a
higher sensitivity as your meter will be out of specification.
The indicator is displayed as UR at the right hand side of the axis measurement
that is causing the under range condition. Any axis where the measured value is
below the Under Range point for that range will be blanked on the display and
shown as a series of '-' characters.
For the display modes HARM, SINGLE and CUSTOM the under range indicator
will remain on for a minimum of 2 seconds or while the under range condition
remains.
For the WBV display mode the under range indicator will remain on for a
minimum of 8 seconds or while the under range condition remains.
Due to the effects of integration when either Velocity or Displacement are
selected in Single Axis mode, the dynamic range is approximately 10dB greater
and therefore the under range indicator in these circumstances is
approximately 10dB lower than other display modes.
See Technical Specification for a complete list of Under Range triggering
points.
Overload Condition
An overload condition occurs when either the peak signal starts to exceed the
signal handling capability of the specialised amplifier circuitry or if the vibration
level exceeds the top of the selected range by 5%. If the vibration source
saturates the input circuitry or is 5% greater than top of the selected range an
Overload condition occurs and an OL indicator is displayed at the right hand side
of the axis measurement that is causing the overload condition.
If an overload condition occurs it is highly recommended to change to a higher
range with a lower sensitivity as your meter will be out of specification.
For the display modes HARM, SINGLE and CUSTOM the overload indicator will
remain on for a minimum of 2 seconds or while the overload condition remains.
For the WBV display mode, the over load indicator will remain on for a minimum
of 8 seconds or while the over load condition remains.
Please be aware that the selected frequency weighting may attenuate the
displayed signal level below the overload triggering point but an overload can still
occur. This is because the overload operates from the unweighted input signal.
See Technical Specification for a complete list of Overload triggering points.
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