9.2.3 To Calibrate RTD Input

 

The two points at which the RTD range is calibrated are 150.00Ω and 400.00Ω.

 

Before starting RTD calibration:

 

Connect a decade box with a resolution to two decimal places in place of the RTD as indicated on the connection diagram below before the instrument is powered up. Make sure that the internal resistance of the box, the interconnection leads and any other connections are kept as low as possible – certainly less than 22ohms and preferably <1ohm, as indicated on the connection diagram in section 9.1.4. If at any time the instrument was powered up without this connection then at least 10 minutes should elapse from the time of restoring this connection before RTD calibration can take place.

 

Before calibrating the RTD input the mV range must be calibrated first.

 

Set ‘P1’ to ‘rTD’. Then:-

 

Operation	Do This	Display View	Additional Notes
Select calibration phase	1.        Press or to select PHAS		This is found towards the end of the list of ‘P’ codes.
Set the decade box for 150.00Ω.
Select the low calibration point (150.00Ω)	2.        Press or to choose ‘150r’
Calibrate the low point	3.        Press to select ‘GO’ 4.        Press or to choose ‘YES’ 5.        Press to confirm		The controller automatically calibrates to the injected 150.00Ω input. The display will show busy then pass, (if calibration is successful) or FaiL if not.   FaIL may be due to an incorrect input resistance.
	6.        Press again to enter
Set the decade box for 400.00Ω
Select the high calibration point (400Ω)	7.        Press or to choose 400r
Calibrate the high point	8. Repeat 3 to 6 above to calibrate the high point		The controller will again automatically calibrate to the injected 400.00Ω input.   If it is not successful then ‘FAIL’ will be displayed