Thermocouple Sensors in Singapore
OMEGA Engineering Singapore
Engineering, Sensors, Thermocouple
OMEGA Engineering, the world’s leading Thermocouple manufactures are selling Thermocouple in Singapore also. http://sea.omega.com/sg/subsection/thermocouples-all.html
When two wires composed of dissimilar metals are joined at both ends and one of the ends is heated, there is a continuous current which flows in the thermoelectric circuit. Thomas Seebeck made this discovery in 1821. It is also called as thermocouple sensor.
If this circuit is broken at the center, the net open circuit voltage is a function of the junction temperature and the composition of the two metals. All dissimilar metals exhibit this effect.
Measuring Thermocouple Voltage - We can’t measure the voltage directly because we must first connect a voltmeter to the thermocouple, and the voltmeter leads themselves create a new thermoelectric circuit. Depending on application there are many type of thermocouple sensors are available now.
The measuring junction is placed in the environment whose temperature is to be measured. For precision work, the reference junction is kept at a fixed, known temperature (for example, by being placed in an ice bath). If great precision is not required, the reference junction may be left at room temperature, which is known only approximately. The potential difference between the two junctions, as shown by the potentiometer or voltmeter, is used to find the temperature of the heated junction, usually from a table in a handbook.
When used as a control device in a gas appliance, the thermocouple is mounted so that its measuring junction is heated by a pilot light. The electric current generated is sent through an electromagnet. As long as the current flows, the electromagnet holds open a valve that allows gas to reach the appliance. If the pilot light goes out, the measuring junction cools off, no current flows, and the electromagnet releases the valve, shutting off the gas.
A number of thermocouples connected in series make up a thermopile. Thermopiles are more sensitive than individual thermocouples (some thermopiles can measure temperature differences as small as a millionth of a degree). Thermopiles are used for measuring the temperature of radiation from stars, for detecting the amount of heat produced by living tissues, and in other situations where highly sensitive temperature-measuring devices are required.