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Thermocouple Sensors

What Is A Thermocouple?

A Thermocouple is a sensor used to measure temperature. They are 3 options for how many junctions can be found in a Thermocouple, a simplex Thermocouple (two wire) a duplex Thermocouple (4 wire) & a triplex Thermocouple (6 wire). To create a junction the wires need paired, each pair consists of two dissimilar metals, when welded together this is known as a hot junction. Once the junction of the Thermocouple has been welded and has contact with a heat source, this creates a milivoltage. The milivoltage travels along the Thermocouple wire, which can then be converted in to temperature using Thermocouple reference tables to calculate the temperature.

Northeast Thermocouple Sensors Ltd can manufacture the following:

                                                                              Type K Thermocouple                + Chromel / – Alumel

                                                                              Type J Thermocouple                 + Iron / – Constantan

                                                                              Type N Thermocouple               + Nicorsil / – Nisil

                                                                              Type T Thermocouple                + Copper / – Constantan

                                                                              Type E Thermocouple                + Chromel / – Constantan

                                                                              Type R Thermocouple                + Copper / – Alloy 11

                                                                              Type S Thermocouple                + Copper / – Alloy 11

RTD (PT100)

What Is An RTD?

Utilising a high precision sensing resistor, usually of platinum, the resistance value of which increases with temperature. The platinum sensing resistor is highly stable and allows high accuracy temperature sensing. RTD’s offer excellent accuracy over a wide temperature range (from –200 to +850 °C) with various accuracy specifications and numerous packaging options to suit most applications. Unlike Thermocouples, it is not necessary to use special cables to connect to the sensor. The principle of operation is to measure the resistance of a platinum element. The most common type (PT100) has a resistance of 100 ohms at 0 °C and 138.4 ohms at 100 °C.

Northeast Thermocouple Sensors can manufacture your RTD in the following configurations:

Simplex RTD – 2 wire, 3 wire, 4 wire

Duplex RTD – 2 wire, 3 wire, 4 wire

               Thermocouple’s are generally:                                        RTD’s are generally:

                    Relatively inexpensive                                              More expensive

                    More rugged                                                              More accurate

                    Less accurate                                                             Highly stable

                    More prone to long-term drift                                Capable of better resolution

                    More sensitive                                                           Restricted in their range of temperature

                    Tip sensing                                                                 Stem, not tip sensitive

                    Available in smaller diameters                               Rarely available in small diameters

                    They do need special cabling                                 They do not need special cabling