Thermocouple with unified 4-20 mA output THAU-002, THKU-002, TZHKU-002

Thermocouple with 4-20 mA output (thermoelectric temperature converter, temperature sensor with standardized 4-20 mA current output signal) THAU-002, THKU-002, TZHKU-002 is designed to convert the temperature of the working junction of the thermocouple into thermo-EMF and further convert it into a standardized 4-20 mA current output signal. Thermocouples are used for measuring the temperature of liquid, bulk, and gaseous media that do not contain substances interacting with the material of the protective fitting and connecting cable. The application area of thermocouples with a unified 4-20 mA output signal includes temperature control and regulation systems of technological processes in various industries, agriculture, municipal economy, and everyday use. Thermocouple Operating Principle The operating principle of the thermocouple is based on the Seebeck thermoelectric effect. The thermocouple has two joined ends; one end is placed in the measurement medium called the measuring or hot junction, and the other end at the connection point to the input device is called the cold junction. Methods of making the hot junction are shown in Figure 1. When there is a temperature difference between the hot and cold junctions, thermo-EMF arises in the circuit, the value of which is applied to the input. Figure 1 - Methods of Making the Hot Junction The measuring junction is placed in protective fitting. Thermocouple junctions are made in various configurations. Junctions can be grounded or ungrounded, and two-element thermocouples can be insulated or uninsulated. Hot junction configurations are shown in Figure 2. Figure 2 - Hot Junction Configurations Grounding of thermocouple junctions occurs when the thermocouple junction is connected to the shell of the primary converter. Grounded junctions have better thermal conductivity, which in turn increases response speed. However, grounding also makes thermocouple circuits more susceptible to electrical noise that may distort the thermocouple voltage signal if the measuring instrument does not provide isolation. All high-quality measuring converters and input/output boards provide electrical isolation as standard. A grounded junction is also more susceptible to contamination by chemical impurities over time. An open junction thermoelectric converter has a hot junction protruding from the sealed end of the sheath, providing high response speed. Sealing prevents moisture or other contaminants from entering the sheath. Usually, such thermocouples are applied only in non-corrosive gases, for example in air ducts. Ungrounded junctions occur when thermocouple elements do not merge with the primary converter sheath but are surrounded by insulating powder. Ungrounded junctions have somewhat lower response speed than grounded junctions but are less sensitive to electrical noise. Structurally, a thermocouple with 4-20 mA output (modification - 002) is a temperature sensor modification 002 with a printed circuit board of the 4-20 mA converter built into the terminal head. Main Technical Specifications of 4-20 mA Thermocouples Operating temperature range, depending on thermocouple type - (0-1100) °C; Ambient temperature range around the 4-20 mA converter board - from 5 to 55 °C; Measuring element connection scheme - two-wire; Thermocouple type with 4-20 mA output - K, L, J; Protective fitting material - stainless steel 12X18H10T; Protection degree against dust and water ingress - IP54; Design - non-detachable; Insulation resistance - not less than 100 MΩ; Output signal - 4-20 mA; DC supply voltage - 12-36 V; Maximum current consumption - 40 mA; Maximum allowable main error - 1% (regulated for temperature 25°C during operation of the 4-20 mA converter board). You may also be interested in thermoelectric temperature converters with standardized 4-20 mA output signal (modification - 001) THAU-001, THKU-001, TZHKU-001, which unlike modification 002 do not have a movable or welded fitting. Full designation of thermocouples when ordering: REGMIK-PTU-THAU-002, REGMIK-PTU-THKU-002, REGMIK-PTU-TZHKU-002.