Hanse VTC Series, Installation, Operation And Maintenance Instructions

Page: 30 / 91

704-GRMS System Calibration (Chambers Pre 2006)
Note: Material Taken from the JC 704 Calibration Procedure manual
Background:
The calibration of the Model 704_GRMS consists of setting 0 Grms and 100 Grms
vibration levels.
The output is calibrated for 0 Grms input and should produce 0.0 vdc output
corresponding to 0 Grms.
The output gain of the GRMS Model-704 is adjusted to produce 1.0 vdc for the
equivalent of 100 Grms at the input to the GRMS Model-7004. (All predicted on a 10
mv/Grms accelerometer).
Calibration Procedure
EQUIPMENT REQUIRED:
True RMS DVM (Digital Volt Meter), Sinewave Generator, 4 ea. 2K ohm, 1% resistors
( Dummy Loads), 1 ea. 1K ohm, 1% resistor, Accelerometer Simulator (Build simulator
as shown on page 48).
HOOK UP:
Connect 117VAC to Line inputs: TB3 - 1 (Hot), - 2 (Neutral) & - 3 (GND).
Apply power to the unit.
MEASURE THE DC SUPPLY VOLTAGES:
Connect the negative meter lead to TB1 pin 2, 4, 6, 8 or 10 ( 0 VDC).
NOTE:
Leave the negative meter lead connected during the remainder of the procedure.
Measure the - 15.0 VDC by connecting the positive meter lead to pin 4 of either U12 or
U13.
Measure the + 15.0 VDC by connecting the positive meter lead to pin 7 of either U12 or
U13.
MEASURE THE ACCELEROMETER SOURCE CURRENTS:
Place a 2K ohm resistor in series with the positive meter lead.
Place the resistor/meter in series with the “X” accelerometer input. Measure & record
the constant current.
The current at each input must be 5.2mA, +/- 0.3mA. (4.9mA - 5.5mA)
This can be done by using the free lead of the resistor as a probe and inserting it into
the center (+)
conductor of the associated inputs BNC connector.
Replace the 2K ohm resistor with the 1K ohm resistor. Measure each of the
accelerometer inputs again. The reading must be exactly the same as that measured
with the 2K re/- 0.00mA.
Authorization and Copyright of this document is
controlled by Hanse Environmental Inc.
30