Input Wiring
Figure 8a – Thermocouple
Extension wire for thermocouples must be of the same alloy as the thermo-
couple itself to limit errors.
Figure 8b – RTD (2- or 3-Wire) 100Ω Platinum
There could be a +2°F input error for every 1Ω of lead length resistance
when using a 2-wire RTD. That resistance, when added to the RTD ele-
ment resistance, will result in erroneous input to the instrument. To over-
come this problem, use a 3-wire RTD sensor, which compensates for lead
length resistance. When extension wire is used for a 3-wire RTD, all wires
must have the same electrical resistance (i.e. same gauge, same length,
multiple-stranded or solid, same metal.
Figure 8c – Process,4-20mA Figure 8d – Process,0-5VÎ (dc)
Input impedance: 5Ω Input impedance: 10kΩ
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