SM0486
(a) calculate the corrected sensitivity of the pickup and divide the
corrected sensitivity of pickup by 10.
(b) With the input network and range selectors in any position, set the
channel selector to the channel to be calibrated.
(The pickup may be either
connected or disconnected.)
(c) Turn the operation selector to C and then depress and turn the
calibrate signal control. Turn the control until the meter indication as read on
the lower scale corresponds to the corrected sensitivity in millivolts per inch per
second divided by 10, as previously calculated.
(d) Release the calibrate signal control and adjust the meter to read
full scale by using the sensitivity control applicable to the channel in which a
pickup is to be used.
(e) Each channel using a pickup is calibrated according to the procedure
discussed in the previous steps. In each case, the appropriate channel sensitivity
control should be used.
(2) In the preceding steps of the calibration procedure, you are adjusting
the sensitivity of the meter to the corrected sensitivity of the pickup.
This
completes our discussion of the vibration meter.
Let's proceed to the typical
pickup calibrator.
6.
VIBRATION PICKUP CALIBRATORS. The material covered in this chapter is included
to help you understand how mechanical vibrations can be detected by means of a
pickup and how the displacement or velocity resulting from the vibration can be
measured by using a typical vibration meter. A typical meter calibration procedure
is included so that you can know the basic steps involved in assuring that the
vibration meter sensitivity matched that of the pickup. Information is included in
this section to help you understand how vibration pickups are calibrated. We will
discuss the major components of the PC1-A Vibration Pickup Calibrator, its
operating theory, and the procedure need to calibrate a pickup.
a. Vibration Exciter.
The vibration exciter consists
of
two
major
components: the body structure and the moving element assembly.
(1) The body structure contains two permanent magnets which are used to
supply two separate field of magnetic force across annular air gaps.
The moving
element assembly consists essentially of the following:
Driver coil.
A signal generating coil.
An exciter table.
Two support flexures.
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