Hi,

I have problem reading accurate temperatures using thermocouples. I have
a 40' long refrigerator divided into 4 compartments (3 rooms used for
testing and the fourth houses my electronics). In each room I have a
thermocouple suspended from the ceiling to mid-height of the room. These
thermocouples are connected via thermocouple extension wire to a
National Instruments cFP-1804 module and connected to an isothermal
connector block. Additionally, each room is kept at different
temperatures (ie- room 1: -10C, room 2: -15C, room 3: -20C, room 4:
-30C) and the wire is terminated in the coldest room (room 4).

 

My problem is as rooms 1-3 are heated up (via heaters) the temperatures
read are incorrect. If I read the temperatures at the thermocouple
directly they read the correct room temperature. When I read the
temperature at the end of the thermocouple extension wire it reads a
much colder temperature (I am using a handheld meter). The same problem
occurs when I use my National Instrument device. I need the temperatures
read to be accurate (I have a program that uses these temperatures to
make a series of decisions) but am unable to find out why I am having
such problems. Can anyone out there lend there expertise?

 

Rachid

 

 

 

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