SM0486
turned clockwise, if the circuit is operating properly.
After the preliminary
circuit checks and control settings have been made, the measurement procedure
should be performed as follows:
(a) If pickups being used are not connected, they should be plugged into
meter circuits as required.
(b) Calibrate or match each pickup with the channel in which it is used.
(c) Locate or mount the pickup firmly on the structure to be measured.
For some studies, a pickup may be manually attached to the structure member with
screws and bolts.
(d) Set the channel selector for connection with the pickup whose output
is being metered.
(e) If a pickup signal is to be metered without the use of filters or
other modifying methods, turn the input network control to its OUT position.
(f) If you use filters or similar devices in the metering circuit, turn
the input network control to its proper number in order to introduce the desired
conditioning effect on the signal.
The filtering unit must be plugged into its
proper internal socket.
(g) To measure peak-to-peak displacement, turn the operation selector to
one of the D positions.
(h) For average velocity measurement, turn the operation selector to one
of the V positions. You should adjust the range switch so that meter readings will
be above midscale. If the switch is set to the 5, 50, or 500 position, read the
upper scale figures. If the switch is set to the 15, 150, or 1500 position, read
the lower group of figures.
(6) You can use any readout device whose characteristics are compatible
with the vibration meter.
d. Meter Calibration.
Although you are required to calibrate all precision
measuring equipment in accordance with the procedures outlined in technical
bulletins, the calibration of the meter is important enough that some of the
individual steps should be included in this section.
We are not interested in
teaching a procedure, but we hope that the inclusion of the steps in the procedure
helps you to understand the principles applied when the meter is calibrated.
(1) In order to assure the proper calibration of a vibration meter, the
pickup must be calibrated as previously discussed.
The corrected sensitivity for
the pickup must also be calibrated. After preliminaries have been completed, the
internal test voltage can be used in the calibration of the meter.
You should
proceed as follows:
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