Omega Engineering CL521 Operator's Manual page 26

B) Reference junction compensation using a Pt100 probe, CJ MODE = PROBE
C) Manual reference junction compensation, CJ MODE = MAN
A) INTERNAL REFERENCE JUNCTION COMPENSATION, CJ MODE = INT
The CL521 replaces the thermocouple in the measurement circuit and is connected with
thermocouple wire or thermocouple extension wire. The thermoelectric potential created
by the connections at the simulator binding posts is automatically eliminated with the aid
of the internal temperature sensor. This is a simple method to account for reference
junction temperature. Remember to use the correct type and polarity of extension wires.
B) REFERENCE JUNCTION COMPENSATION USING A PttOO PROBE
CJ MODE = PROBE
The CL521 is connected to the measuring circuit with copper wires. An extra
thermoelectric potential occurs at the point where the copper conductors are attached to
the thermocouple extension wire. The temperature at this point is measured with a
PtIOO probe connected to the CL521. When using this method, no problems arise from
connection wire type and polarity, it is, however, necessary to place the Pt100 probe at
the connections so that it will be at the same temperature as the connections for which
the compensation is necessary.
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