Screening Services and
Training
Last
Update 10/06/2005
25092 Natama
Ct
Based upon a procedure written by Screening Systems, Inc.
Laguna Hills, CA 92653-5607
How to: Calibrate the Single-Board Interface SCM-100
Accelerometer Electronics using the Internal Signal Generator.
This
procedure applies to systems manufactured by Screening Systems, Inc.
that use the SSC-2000 model vibration controller driving the single
board, or two board, SCM-100 interface.
To use the internal signal generator to calibrate the SCM-100
accelerometer electronics requires the internal signal generator output
be within specifications. To verify the accuracy of the
internal
signal generator, connect an external sinewave function generator (FG)
to the Control Accelerometer 1 (X1) BNC accelerometer input connector.
Set the FG to 100.0 +/- 0.5 mVrms at 464 +/- 10 Hz. sinewave
output.
Perform
the calibration of the SCM-100 (X1) accelerometer electronics
by
selecting Configure > Calibrate > Accelerometer (Old
style if
asked to select a style) from the main menu bar on the screen. This
will bring up the
Vibration Calibration pop-up window.
Left mouse on the “Input Channel” bar and select
the top
most selection, “Control Accelerometer 1
(X1)”.
Set the “Input Level” to 10.00 Grms. Left
mouse on
the "START (F2)" button. When the Seconds down-counter reaches
“0”, write down the value in the X1
Offset window at
the upper left corner of the pop-up window.
Now select "Internal Calibration Signal (All Channels), the bottom most
selection from the Input Channel bar. Verify/set the
“Input
Level” to 10.00 Grms. Left mouse on
the "START (F2)" button. When the Seconds down-counter reaches
“0”, write down the value in the "Int"
window located
two windows to the right of the Input Channel bar.
Compare this value with the number written down in
the
previous steps.
If both values are within +/- 1.0% of each other, the
internal
signal generator is within specifications and the accelerometer
electronics calibration data just obtained may be used. In
this
case, left mouse on the "USE INTERNAL (F4)" button to copy
the Offset value to the offset boxes of all Control, Averager and
Auxiliary readings. Read and record the offset value then
select
"EXIT (F1)" and "YES" to save the changes. This completes the
calibration procedure.
If both values are not within +/- 1.0% of each other, the internal
signal generator is not in calibration and its settings must be
adjusted. This is accomplished by removing the cover
from the SCM-100 and allowing the
SCM-100 to warm up for 30 minutes. Using NIST traceable
instruments
check and adjust the following parameters between pins 10 of U19 and
signal ground on the Analog board.
Check that the amplitude of the signal is 100.0 +/-0.5 mV
rms. Adjust potentiometer R37 for the amplitude.
Check that the frequency is 464 +/-10 Hz. Adjust
potentiometer R40 for the frequency.
After
reinstalling the cover on the SCM-100, starting
the SSC-2000 program, and warming up the system for 30 minutes, perform
the internal calibration of the SCM-100 accelerometer electronics by
selecting Configure > Calibrate > Accelerometer (Old
Style if
asked to select a style) from the main menu bar on the screen.
This will bring up the
Vibration Calibration pop-up window.
Left mouse on the “Input Channel” bar and select
the
“Internal Calibration Signal (All Channels)”
option.
Set the “Input Level” to 10.00 Grms. Left
mouse on
the "START (F2)" button. When the Seconds down-counter reaches
“0”, left mouse on the "USE INTERNAL (F4)" button
to copy
the Offset value to the offset boxes of all Control, Averager and
Auxiliary readings. Read and record the offset value then
select
"EXIT (F1)" and "YES" to save the changes.
This completes the calibration procedure.
For technical assistance contact Screening Services and Training via
e-mail. scrserv@cox.net
