Connect the shield to a common-mode voltage reference on the
thermocouple. A valid common-mode voltage reference is a
voltage that is within ±1.2 V of the common-mode voltage of all
the connected thermocouples
Minimizing Thermal Gradients
Changes in the ambient air temperature near the front connector
or a thermocouple wire conducting heat directly to terminal
junctions can cause thermal gradients. Observe the following
guidelines to minimize thermal gradients and improve the system
accuracy.
• Use small-gauge thermocouple wire. Smaller wire transfers
less heat to or from the terminal junction.
• Run thermocouple wiring together near the spring-terminal
connector to keep the wires at the same temperature.
• Avoid running thermocouple wires near hot or cold objects.
• Minimize adjacent heat sources and air flow across the
terminals.
• Keep the ambient temperature as stable as possible.
• Make sure the NI 9213 terminals are facing forward or
upward.
NI 9213 Getting Started Guide | © National Instruments | 13
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