Thermocouple Sensors

Temperature Sensor Basics

Thermocouples have two dissimilar metal wires joined at the hot junction. As temperature changes, a millivolt signal is read at the cold junction. The most common types of temperature thermocouples are type J thermocouples and type K thermocouples. Advantages of thermocouple sensors include: low cost, small size, wider temperature ranges and faster response than RTDs. The disadvantages of using temperature thermocouples include: they are less linear and accurate than RTDs, a matching extension wire is needed, and thermocouples are sensitive to electrical noise.

Resistance Temperature Detectors (RTDs) have a linear increase in resistance as temperature rises. RTDs come in 2-,3- or 4-wire versions. A 2-wire RTD signal is affected by the distance to the controller. 3-wire or 4-wire RTDs can compensate for line losses.

AutomationDirect offers a variety of industrial thermocouple temperature sensors:

Probes

• with Connection Head
• Spring-loaded with Connection Head
• with Hex Nipple
• Spring-loaded with Hex Nipple
• with Attached Plug
• with Lead Wire Transition
• Heat trace with connection head
• Flange mount
• Cuttable length
• Melt bolt

Sensors

For more thermocouple products, see the Temperature Sensors & Transmitters Category:

• Temperature Transmitters (Thermocouple Input)
• Programmable Temperature Transmitters (T/C or RTD Input)