How to distinguish between thermocouple and thermal resistance

Thermocouple temperature sensor is a kind of test, as well as thermal resistance temperature sensor, but he and thermal resistance difference mainly lies in:

a, signal, the properties of heat resistance itself is resistance, the change of temperature, the resistance produce positive or negative resistance changes; And thermocouple, it is the change of the induced voltage, he along with the change of temperature change.

2, two kinds of sensors to detect temperature range, thermal resistance 0 - general detection The temperature range of 150 degrees, high measurement range of up to 600 degrees ( Of course can detect negative temperature) 。 Thermal coupling can detect 0 - Temperature range of 1000 c ( Even higher) So, the former is low temperature detection, which is high temperature detection.

3, from material, heat resistance is a kind of metal material, is sensitive to temperature change of metal materials, thermal coupling is bimetallic material, both of two different metals, due to the changes of temperature, in two different electric potential difference at both ends of the wire.

4, PLC corresponding thermal resistance and thermocouple input module is also different, this sentence is no problem, but the general PLC are directly connected to the 4 ~ 20 ma signal, and the thermal resistance and thermocouple are generally transmitter to access with a PLC. If access to DCS don't have to use the transmitter! Thermal resistance is RTD signals, thermocouple is TC signal!

5, PLC also has the thermal resistance and thermocouple module, which can directly input resistance and thermocouple signals.

6, thermocouple J, T, N, K, S and other models, there are more expensive than resistance, there are also cheaper than resistance, compensation conductor, but on the comprehensive cost of the thermocouple is high. Thermal resistance is the resistance signal, the thermocouple is a voltage signal.

7, thermal resistance temperature measurement principle is based on a conductor ( Or a semiconductor) To measure the properties of resistance varies with temperature changes, commonly used have the platinum resistance ( 装Pt100 Pt10) Cu50, copper resistance ( Negative 50 - 150 degrees) 。

8, thermocouple temperature measurement principle is based on the thermoelectric effect to measure temperature, commonly used have platinum rhodium - — Platinum ( Index # S, measurement range 0 ~ 1300 degrees) Chromium, nickel - — Nickel silicon ( Index number K, measurement range 0 ~ 900 degrees) Chromium, nickel - — Constantan ( Dividing E, measurement range 0 ~ 600 degrees) , platinum rhodium 30 - — Platinum rhodium 6 ( Dividing B, measurement range 0 ~ 1600 degrees) 。

the distinction between thermocouple and thermal resistance method one: according to the sign is to determine the thermocouple or heat resistance, nameplate on concrete have the thermocouple or heat resistance specifications and product information, we can tell as long as careful observation and distinguish is the thermocouple or heat resistance.

the distinction between thermocouple and thermal resistance method one: according to the structure is to differentiate between the thermocouple or heat resistance, thermocouple generally by the hot electrode, insulation pipe, casing protection and junction box parts, such as heat resistance is the sensor output is in series with the load and power supply.

the distinction between thermocouple and thermal resistance method one: through the wiring board to determine, there are negative to distinguish between the thermocouple, not is negative to distinguish is the thermal resistance.

also can see the number of connection: heat resistance is generally three wire system, double branch six lines; Single thermal resistance few adopts only two wire system; Thermocouple, generally two wire system, double branch of four lines.