A temperature measuring sensor. If two wires of different metals are joined at their ends to form a loop, and a temperature difference between the two junctions unbalances the contact potentials, a current will flow round the loop. The temperature of one junction is kept constant and the temperature of the other is indicated by measuring the current.
When two unlike metals are joined to form a circuit and there is a temperature differential between the junctions an electric current is produced. The current can be made be made to do useful work by exciting an electro-magnet, which will hold a valve open while ever the junction between the two metals is hot. When the junction cools the current ceases to flow and the magnet allows the valve to close. This is the principle used by gas control valves to determine whether the pilot burner is alight and hence if it is safe to supply gas to the main burner. If the pilot is not alight a dangerous situation could arise if large quantities of gas are supplied to the main burner but there is no source of ignition to light the gas-perhaps until someone walks past and lit a cigarette. By this time there could be many litres of unburnt gas in the vicinity. A further application of the thermocouple is in testing of appliances. By measuring the current produced, the temperature of the hot junction can be determined. This is used as a means of determining temperatures of floors, appliance jackets, spot temperatures etc. without the use of a thermometer.
A device which uses a circuit of two wires of dissimilar metals or alloys, the two junctions of which are at different temperatures. A net electromotive force (emf) occurs as a result of this temperature difference. The minute electromotive force, or current, is sufficient to drive a galvanometer or amplifier. A temperature sensing device used to measure the temperature of the barrel and nozzle zones.
Two pieces of dissimilar metal welded or brazed together at one end. When the welded end is at a different temperature from the free ends, an electrical voltage is developed that can be measured across the free ends, and that is proportional to the temperature difference and can, therefore, be used to measure the temperature at the brazed end.
a kind of thermometer consisting of two wires of different metals that are joined at both ends; one junction is at the temperature to be measured and the other is held at a fixed lower temperature; the current generated in the circuit is proportional to the temperature difference
a temperature sensing device containing one or more junctions of two dissimilar metals which produce an electrical potential that is a measure of the temperature of the medium to which the junctions are exposed
a thermoelectrial device used to exactly measure temperatures, specially that consist of two united dissimilar metals so that a generated potential difference between the meeting points measures the temperature
A device consisting of two pieces of dissimilar metals joined together at one end (hot junction). When the hot junction is heated, the thermocouple produces DC voltage across the other end. Used to power thermoelectric gas valves.
a pair of junctions of two fine wires (dissimilar materials) that produces a small voltage proportional to the difference in temperature between the two junctions. A number of thermocouples arranged in series form a thermopile.
A device for measuring temperature where two electrical conductors of dissimilar metals are joined at the point of heat application and a resulting voltage difference, directly proportional to the temperature, is developed across the free ends. Reference to standard tables is made to determine the temperature.
Popular temperature sensor because of its low cost, wide operating range and ruggedness. Consists of two dissimilar metals joined together, making a continuous loop. When one junction has a different temperature from the other an electromotive force (voltage) occurs. There are several types of thermocouples, constructed from different metals and with differing temperature ranges and accuracies. More details of thermocouples are in Issue 5 of our newsletter, Monitor.
A device consisting of two pieces of dissimilar metals joined together at one end (hot junction). When the hot junction is heated, the thermocouple produces DC millivolts between 25-30 millivolts. Used to power the gas safety valve.
A temperature sensor based on the principle that a voltage is produced when two dissimilar metals. The junction produces a voltage in proportion to the difference in temperature between the measuring junction and the reference junction.
A device consisting of two dissimilar metals joined together at both ends. The thermoelectric voltage developed between the two junctions is proportional to the temperature difference between the junctions. Thus the device is used to measure the temperature at one of the junctions when the other is held at a fixed, known temperature.
A 2-wire temperature measurement sensor constructed of two dissimilar metals which form a junction. Current flows from one metal to the other in proportion to temperature. A millivolt signal is then measured by a thermometer or other device to display temperature.
A temperature-sensing element which converts thermal energy directly into electrical energy. In its basic form it consists of two dissimilar metallic conductors connected in a closed loop. Each junction forms a thermocouple. If one thermocouple is maintained at a temperature different from that of the other, an electrical current proportional to this temperature difference will flow in the circuit. The value varies with the materials used. Couples of copper and constantan, which generate approximately 40 microvolts per °C of couple temperature difference, are often used for meteorological purposes.
A probe that consists of two dissimilar metals joined at the hot junction. When heated it produces a small electrical current that passes down the Centre of s co-axial conductor to an electro-magnetic valve located in the FFD.
A device that monitors the pilot flame of a pilot model propane appliance. If the pilot flame is extinguished, the thermocouple causes the gas valve to shut off the flow of gas to both the pilot flame and the main burner.
A junction of two dissimilar metals used to measure temperature. The output is a non-linear millivolt signal proportional to the temperature differential between the junction and the point of voltage measurement. See also RTD, LVDT, and Cold Junction Compensation.
A device for measuring temperatures, consisting of lengths of two dissimilar metals or alloys that are electrically joined at one end and connected to a voltage-measuring instrument at the other end. When one junction is hotter than the other, a thermal electromotive force is produced that is roughly proportional to the difference in temperature between the hot and cold junctions.
A device which can measure temperatures, usually by contacting the device to be measured. The device is made from a junction of dissimilar metals, as the junction changes temperature, a voltage is created which is read by a previously calibrated meter.
temperature-sensing element that converts thermal energy directly into electrical energy. In its basic form it consists of two dissimilar metallic electrical conductors connected in a closed loop. Each junction forms a thermocouple. One thermocouple is maintained at a known temperature (usually 0°C or a measured temperature) and the other thermocouple is used to measure the unknown temperature. The signal voltage is a function of the temperature, and the smooth curve can be handled with a simple linear fit over a moderate temperature range. Different materials have different curves. Popular thermocouples (and change in voltage per °C) include iron- constantan (50 mv per °C), copper-constantan (38 mv per °C), and various platinum alloys. Thermocouples are also important in home furnaces to detect the pilot light or that the fuel has ignited. A chain of thermocouples, called a thermopile, can be used as a power supply if a source of heat and cold is available.
A temperature sensor that includes a junction of two different metals. Temperature can be derived from the voltage produced at the contact point of the metals. Opto 22 SNAP I/O analog input modules, such as the SNAP-AITM and the SNAP-AITM2, are available for connecting thermocouples to control systems.
A device for measuring temperatures by the use of two dissimilar metals in contact; the junction of these metals gives rise to a measurable electrical potential which varies with the temperature of the junction. Thermocouples are used to operate temperature indicators or heat controls.
A thermoelectric device consisting of two dissimilar metals joined so that a potential electrical difference generated between the points of contact is a measure of the temperature difference between the points.
A device, consisting of two dissimilar metallic conductors in contact. that produces an electrical current whose magnitude depends upon the temperature of the junction. The resulting temperature measurement feeds into a pyrometer to help monitor and control the temperature of a barrel or nozzle. The thermocouple is housed in a steel tubing adapter.
A pair of dissimilar conductors joined to produce a thermoelectric effect and used to accurately determine temperature. Thermocouples are used in laboratory testing of motors to determine the internal temperature of the motor winding.
A device used to measure temperature, consisting of two dissimilar metals joined together so that the difference in voltage can be measured. Voltage changes in proportion to temperature, therefore the voltage difference indicates temperature differences.
In electronics, thermocouples are a widely used type of temperature sensor and can also be used as a means to convert thermal potential difference into electric potential difference. They are cheap and interchangeable, have standard connectors, and can measure a wide range of temperatures. The main limitation is accuracy; system errors of less than 1 Â°C can be difficult to achieve.