Cropico 3000 SERIES Instrukcje Operacyjne Pobierz pdf (Strona 16)

3000.doc Iss. 2/00

The 3000 series of precision thermometers has been designed to give long service and permanence of

calibration together with a low cost of ownership. Attention to detail in the design stage has produced

an instrument that is quick and simple to recalibrate with the minimum of equipment . Prior to

calibration the unit should be placed in a temperature controlled environment for a minimum of 4

hours, care could be taken to use good quality test leads, thus avoiding any thermal emf, together with

resistance standards of known value. To select the Cal option press the MEM key and then select the

Cal option from the menu. The calibration counter number will be displayed, a second menu choice

will be given Cal or Prt. The Prt option will print the calibration constants to the screen, this is used

as a diagnostic tool to ensure that there is no corruption of these constants. Select the Cal option and

you now enter the calibration routine. The display will ask for a passcode to be entered, the default

passcode number is 9252, enter this number and press OK. Any number between 0 and 9999 is valid.

The display will then give you the option of changing the passcode to your own personal number, if

you select Yes you will then be asked to enter your chosen number via the keypad ending by pressing

OK. You will then be asked to confirm your number. Once the new number is accepted the calibration

counter will increment 1. The display will then give a choice of calibration RTD, T/C, RJA, RJB, it is

preferable to calibrate the RTD ranges first.

RTD CALIBRATION

Select this option by pressing the key below RTD, the display will then prompt you to connect 100

ohm resistance standard to channel A. When connected press OK and you will be prompted to enter

the exact value of the standard. Once the value is entered and the OK pressed you will be asked to

confirm the value by pressing OK again. The instrument will then calibrate itself against this standard

storing the calibration constants in the memory. Next you will be asked to connect a 400 ohm

resistance standard and repeat the above. Finally you will by prompted to connect a 250 ohm

resistance standard and again repeat the above. Once this calibration is completed the display will

return to the main calibration menu. At this point you have the option of calibrating the thermocouple

range or pressing QUIT key to return to the measuring mode.

THERMOCOUPLE CALIBRATION

Select this option by pressing the T/C key in the calibration menu. Connect a mV source to the

thermocouple input of channel A using low thermal copper leads and connectors. The display will

prompt you to set the input to 0mVdc and press OK. Next +75mVdc should be supplied and OK

pressed, finally -75mVdc should be supplied and again the OK pressed. These three values will

calibrate the complete thermocouple range of the instrument. The display will again return to the main

calibration screen and the reference junction should now be calibrated.

RJ CALIBRATION

The reference junction of both channel A and channel B should be calibrated. Select RJA, insert a

Pt100 standard thermometer in the 4mm negative (lower) input socket of channel A and allow the

temperature to stabilise, it is necessary to use a sensor that fits securely into this socket. Once the

temperature of the socket has stabilised and a steady temperature reading is obtained, enter the

temperature into the instrument, the screen will prompt you to enter the block temperature. Confirm

the value and press OK. Repeat this procedure for channel B moving the sensor to the negative input

socket in channel B.

Once both channels have been calibrated you may exit the calibration menu with the QUIT key.

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Cropico 3000 SERIES Instrukcje Operacyjne Strona 16