Calibration - Extech Instruments 48VTR User Manual

Calibration

Important Note: The calibration cannot be aborted once the calibration parameters are
accessed. Do not initiate the calibration process unless you are prepared and qualified. It
is safe, however, to scroll through the 4
1. Access the 4th Menu. 'LoCA' (Low Calibration) is the first parameter.
2. Determine the input type of the controller (the controller part number and label show
the input type) and then connect a Thermocouple (mV), RTD (resistance), 4-20mA, or 1-
5VDC calibrator to the controller's input terminals.
3. Apply the low input signal to the controller, i.e., for a 4-20 mA input controller, apply a
4mA signal to the controller.
4. Use the arrow keys to set the display value that corresponds to the 4mA input. For a 4-
20mA input that will linearly correspond to a display range of 0 to 150, for example, set
'LoCA' to 0.
5. Press and hold the Return key for at least 5 seconds to change from 'LoCA' to 'HiCA'
(High Calibration). The Low Calibration value is now stored in non-volatile memory.
6. Apply the high input signal to the controller. For example, for a 4-20mA input, apply a
20mA signal.
7. Use the arrow keys to set the display range value that corresponds to the 20mA input.
For a 4-20mA input that will linearly correspond to a display range of 0 to 150, in the
example, set 'HiCA' to 150.
8. Press and hold the RETURN key for at least 5 seconds; the meter will return to normal
operation. The High Calibration value is now stored in non-volatile memory.
9. Input a signal midway between the Low and High Calibration points (12mA in the 4-
20mA example above) and verify that the display indicates a value midway between
the high display and the low display values (75, for the 4-20mA example above).
10. If the controller does not indicate the expected display values, re-calibrate the
instrument. For questions, contact Extech support.
th
Menu Level to simply view the settings.
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48VTR User Manual v6.0 10/1/20