Introduction; Routine Calibration; Calibration Equipment; Zero Calibration - Omega RD8800 User Manual

Chapter 6 Calibration

6.1 Introduction

This chapter includes the procedures to calibrate the Analog-to-Digital Converter (ADC) circuit board and the RTD
current source. The actual calibration constants are automatically stored in Flash Memory on the Analog-to-Digital
Converter boards.
WARNING: Do not attempt to perform calibration unless you are fully prepared to do so. Incorrect
procedures can destroy factory calibration. Read this entire chapter before attempting to
calibrate the unit.
NOTE: Allow the Recorder to warm up and stabilize before attempting calibration. A warm up time of 15 minutes
at room temperature is recommended.

6.1.1 Routine Calibration

Routine calibration should be performed to maintain the accuracy of the instrument. The following items must
be performed for a routine calibration:
•
Zero Calibrate all channels
•
Calibrate the ADC Scales
•
RTD Current

6.1.2 Calibration Equipment

The following equipment items are necessary to calibrate the instrument:
•
One precision voltage source (accurate to ± 5 microvolts) adjustable from 10 microvolts to 25 Volts
•
One precision resistor 250 ohms 0.05% - Required for calibrating RTD

6.2 Zero Calibration

Before the Scales or RTD current are calibrated, a Zero Calibration must be done. A Zero Calibration must be done
when new channels are installed into the ADC board.
To perform a Zero Calibration:
Insert a jumper onto all channels (see the Unused Input diagram in Figure 2-7). From the Hidden menu use the UP
(↑ ↑ ↑ ↑ ↑ ) or DOWN (↓ ↓ ↓ ↓ ↓ ) button to highlight ADC Control and then press the ENTER button. The only available option is
Cal Adc so just press the ENTER button. Use the UP (↑ ↑ ↑ ↑ ↑ ) or DOWN (↓ ↓ ↓ ↓ ↓ ) button to highlight Cal scales and press
the ENTER button. Use the UP (↑ ↑ ↑ ↑ ↑ ) or DOWN (↓ ↓ ↓ ↓ ↓ ) button to select Zero cal. and press the ENTER button. A pop
window with "SHORT ALL INPUTS". Press the OK? button. A pop window will show the readings from channel 1.
Press the CAL. button. You will be prompted with "Are You Sure?". Press the CAL. button again to calibrate the
channel or the press the NO button to cancel.
NOTE: Zero calibration must be done to all channels. Only the readings from channel 1 will be shown.
Once the Zero Calibration is done, remove the jumpers and press the EXIT button three times to get back to the
Hidden menu.
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