Calibration
Primary Training
DC Gain correction
Input the value of the DC voltage
connected to the analog input (s)
number : 1
(Range is : 2.828 Volts)
Value = 2 Volts
OK to calibrate input
Offset correction
Apply to the input the same voltage as entered on the screen, then move the cursor to
the [OK] icon, and press [ENTER]. The software starts the gain adjustment. As for
the offset, if this adjustment is unsuccessful it will be indicated by an error message
appearing on the screen.
The error of gain adjustment can be due to the application of a voltage that does not
correspond to the voltage entered on the screen, or to a wrong input range selection, a
mis-placed jumper on the 424 isolation cards, or an unstable DC calibration source
(ripple).
3.3.3.2 AC mode gain calibration
This mode must be carried out using AC voltages or currents.
For optimum precision, a sine-wave generator with a frequency of 50HZ
±
0.1 Hz or
60 Hz
±
0.1 Hz must be used. The program calculates the true RMS value, so check
the input value with a
true
RMS voltmeter of adequate precision. The program
suggests an AC voltage value to be applied to the channel inputs to be calibrated
(approximately 80% of the range). If this voltage is not available, the user can enter
another one instead the one suggested. This voltage must be between 0.1 and the
chosen range. Type <ENTER> to accept this value.
In the following example, the range chosen is 2V RMS on channel 1. The program
suggests 1V RMS. If this voltage is not available, the user can enter any value
between 0.1 and 2V RMS AC (the higher the voltage is, the more precise will be the
calibration. Be carefull when calibrating current inputs for the dissipated heat and do
not exceed the maximum allowed values).
Page 14
9200-14 REV. E
