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Topic: Thermocouple

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	Thermocouple application note from Pico Technology
		In practice, however, thermocouples junctions are made by welding the two metals together (usually by capacitive discharge) as this ensures that the performance is not limited by the melting point of solder.
		If thermocouples with thin leads or long cables are needed, it is worth keeping the thermocouple leads short and then using thermocouple extension wire (which is much thicker, so has a lower resistance) to run between the thermocouple and measuring instrument.
		A similar problem can occur if the thermocouple is not sufficiently immersed in the liquid, due to the cooler ambient air temperature on the wires, thermal conduction may cause the thermocouple junction to be a different temperature to the liquid itself.
	www.picotech.com /applications/thermocouple.html (1843 words)

	Thermocouple
		Thermocouples are calibrated in terms of the emf generated by the measuring junctions relative to the reference junction at 0ฐC; referencing at another temperature therefore does present problems.
		If a thermocouple is to be used reliably for surface sensing, it must be in either exposed, welded junction form with very small thermal mass or be housed in a construction which permits true surface contact whilst attaching to the surface.
		Thermocouples are ideal for such applications since their measuring junctions have a very small thermal mass and are physical small.
	www.w-dhave.inet.co.th /Thermocouple.html (3826 words)

	Thermocouple Technical Reference
		Thermocouples are based on the principle that when two dissimilar metals are joined a predictable voltage will be generated that relates to the difference in temperature between the measuring junction and the reference junction (connection to the measuring device).
		When a replacement thermocouple is required, it is of the utmost importance that the type of thermocouple type used in the replacement matches that of the measuring instrument.
		It is also required that thermocouple or thermocouple extension wire, of the proper type, be used all the way from the sensing element to the measuring element.
	instserv.com /rmocoupl.htm (742 words)

	Thermocouple Theory
		Thermocouples are popular in industrial control applications because of their relatively low cost and wide measurement ranges.
		Since thermocouple voltage is a function of the temperature difference between junctions, it is necessary to know both voltage and reference junction temperature in order to determine the temperature at the hot junction.
		The thermocouple signal is digitized at a higher rate than the reference junction because it is assumed that the reference junction is relatively stable compared to the hot junction.
	www.sensoray.com /html/tcapp.htm (928 words)

	Thermocouple specifcations (Site not responding. Last check: 2007-11-06)
		Thermocouples should be inspected for dents, kinks, and splits in the stainless steel sheath.
		Thermocouples are rugged devices but they should be check for function and calibration if they have been subjected to a mechanical stress or impact.
		When using a thermocouple you should size you thermocouple for the application and insure that at least 1 inch of the thermocouple is submerged in the solution and the solution is well agitated.
	www.i-2-r.com /temp_accessories/p_thermocouples/Notes_on_TCs.htm (459 words)

	NPH's - How Thermocouples Work & Thermocouple Theory letter
		Because the thermocouple is poorly understood, it is often passed over in deference to another temperature measuring device that might be more expensive and less suited to the application.
		Since the EMF generated by thermocouple circuits is a function of the difference in temperatures between the measuring junction and the reference junction, it is important that the reference junction be maintained at a constant, known temperature.
		The basic purpose of the reduced end thermocouple junction is to offer a combination of the physical strength of a large diameter sheathed thermocouple and the response time of a small diameter thermocouple.
	www.nphheaters.com /technical/thermo_letter.htm (1819 words)

	Thermocouple Attachment- A Primer
		Yet despite these problems, thermocouples are the preferred choice for accurately monitoring the temperature of critical points on circuit board assemblies during the soldering process.
		The thermocouple on the left is poorly installed, with a large blob of solder that greatly increases the thermal mass of the leg.
		It is quick and easy to clip the mechanical thermocouple support device to the edge of a board, and to position its thermocouple tip anywhere on the board, even in tight spaces between components.
	www.ecd.com /saunders/basics.htm (2223 words)

	Capgo - Thermocouple Theory (Site not responding. Last check: 2007-11-06)
		The thermocouple is one of the simplest of all sensors.
		The thermocouple's output is generated by the temperature gradient along the wires and not at the junctions as is commonly believed.
		Thermocouples are excellent for measuring temperatures differences, such as the wet bulb depression in measuring humidity.
	www.capgo.com /Resources/Temperature/Thermocouple/Thermocouple.html (2691 words)

	Electronics Cooling: notes on using thermocouples (Site not responding. Last check: 2007-11-06)
		Copper-Constantan thermocouples are very susceptible to conduction error, due to the high thermal conductivity of the copper, and should not be used unless long runs of wire (100 to 200 wire diameters) can be laid along an isotherm.
		The simplest (and cheapest, and quickest) thermocouple probe is simply a pair of wires twisted or crimped together at one end with the other end connected to the terminals of a voltmeter.
		One pair is used as a thermocouple to determine the temperature level, and one pair is used to determine the temperature difference between two points.
	www.electronics-cooling.com /Resources/EC_Articles/JAN97/jan97_01.htm (2281 words)

	Thermocouple Meter (Site not responding. Last check: 2007-11-06)
		A Laureate™ thermocouple meter with a temperature signal conditioner board is a pyrometer which provides a highly accurate temperature indication for multiple thermocouple types and 100 Ohm platinum RTDs.
		The thermocouple or RTD type, range and resolution (1° or 0.1°) are selectable from the front panel or via the meter's serial interface.
		Thermocouple open sensor indication is standard and may be set up to indicate either upscale or downscale.
	www.laurels.com /z-thermocouple.html (263 words)

	thermocouples and thermocouple probes
		Thermocouple: A thermocouple is a thermoelectric device used to measure temperatures accurately, especially ones consisting of two dissimilar metals joined so that a potential difference generated between the contact points measures the temperature.
		In an ungrounded probe, the thermocouple junction is detached from the probe wall.
		In ungrounded junctions, the thermocouple is separated from the sheath wall by a layer of insulation.
	www.omega.com /thermocouples.html (980 words)

	Taking Thermocouple Temperature Measurements- Developer Zone - National Instruments (Site not responding. Last check: 2007-11-06)
		A thermocouple is created whenever two dissimilar metals touch and the contact point produces a small open-circuit voltage as a function of temperature.
		According to the Thermocouple Law of Intermediate Metals, illustrated in Figure 2, inserting any type of wire into a thermocouple circuit has no effect on the output as long as both ends of that wire are the same temperature, or isothermal.
		Assuming that junctions J3 and J4 are the same temperature, the Thermocouple Law of Intermediate Metals indicates that the circuit in Figure 3 is electrically equivalent to the circuit in Figure 1.
	zone.ni.com /devzone/cda/tut/p/id/4237 (1708 words)

	Thermocouple Information from Back Issues of The Salamander News
		The FRK thermocouple is a cast-in type of sensor that is embedded within the element as it is cast.
		Thermocouple usage with ceramic heating elements continues to be a question of world wide concern.
		Keep in mind that a thermocouple, as used in the ceramic heater industry, is a basic tool used to measure as closely as possible, the actual temperature reached inside the heat source.
	www.infraredheaters.com /back3.htm (1851 words)

	Thermocable - Tri-States Grain Conditioning Inc.
		TSGC cables have thermocouples made of copper and constantan (an alloy of copper and nickel), the most sensitive combination made for grain bin temperature scanning systems.
		The number of thermocouples per cable is determined by the depth of the storage structure - six thermocouples per cable is standard in most flat storage installations.
		Thermocouples and leadwires are color coded for quicker hook-up with less chance of error.
	www.tsgcinc.com /tempmon/tc/index.htm (374 words)

	Thermocouple Temperature Sensors, how they work, color codes, recommended limits, limits of accuracy, calibration ...
		Thermocouples are among the easiest temperature sensors to use and obtain and are widely used in science and industry.
		Thermocouples can err in reading their own temperature, especially after being used for a while, or if the insulation between the wires loses its resistance due to moisture or thermal conditions, or there are chemical, nuclear radiation or mechanical effects with the immediate surroundings.
		Thermocouples are pairs of dissimilar metal wires joined at least at one end, which generate a net thermoelectric voltage between the the open pair according to the size of the temperature difference between the ends, the relative Seebeck coefficient of the wire pair and the uniformity of the wire-pair relative Seebeck coefficient.
	www.temperatures.com /tcs.html (1044 words)

	Thermocouple Home Page
		Thermocouples: A thermocouple is a thermoelectric device that is used to measure temperatures accurately.
		Thermocouple are available in different combinations of metals or calibrations.
		Thermocouples measure in wide temperature ranges and can be relatively rugged, so they are very often used in industry.
	www.omega.com /prodinfo/thermocouples.html (1006 words)

	thermocouple
		Instrument which records the variation in current flow are calibrated in terms of temperature and are know as thermocouple pyrometers.
		Thermocouples are made from two different kinds of metals.
		Thermocouples have limited use in temperature spans of less than about 33°C because of the relatively small change in junction voltages with temperature.
	thermometer-thermocouple.info /thermocouple.htm (321 words)

	Thermocouple (Site not responding. Last check: 2007-11-06)
		The thermocouple is a device that generates electricity when heat is applied to the tip of it.
		Copper Tube Thermocouple The tip of the thermocouple sets in the burner flame, and the nut at the other end of the thermocouple screws into the top of the safety valve, or other device.
		At the end of the thermocouple is an insulator that keeps the inside wire from touching the nut which has contact with the outer copper tube.
	www.rvmobile.com /Tech/Trouble/Tcouple.htm (244 words)

	Thermocouple Basics: The Principles and Methods of Using Thermocouples
		The thermocouple provides a simple and efficient means of measuring temperature because it produces a voltage which is a function of temperature.
		In practice, several thermocouple types have become standard because of desirable qualities such as linearity of the voltage drop as a function of temperature and large voltage to temperature ratio.
		Thermocouple tables usually assume that a reference junction is held at 0°C. The configuration of Figure 2 avoids the problem of additional thermoelectric voltages being generated at the instrument as long as the terminals are at the same temperature.
	www.iotech.com /mcjun96.html (1012 words)

	ITS-90 Thermocouple Database, How to Use the Database
		Similarly, to view a table of coefficients of a particular thermocouple type, select the desired table for that particular type from the coefficients drop-down menu at either the top or bottom of the current table.
		The thermocouple reference functions cannot be inverted exactly with a finite number of coefficients; consequently the inverse functions are only approximate, to within the errors stated in the tables of coefficients.
		When the other ends of the thermocouple are maintained at a known reference temperature, the thermoelectric voltage produced by the thermocouple is a repeatable function of the temperature of the measuring junction.
	srdata.nist.gov /its90/useofdatabase/use_of_database.html (1092 words)

	HOBO Thermocouple Data Loggers
		These thermocouple data loggers also have a second channel with an internal temperature sensor which can be used to record ambient temperatures.
		Thermocouples are popular for their wide temperature range and specialized probes.
		Thermocouple probes, connectors, and wires are warranted for manufacturing defects on receipt only.
	www.microdaq.com /occ/other/hobotc.php (500 words)

	eFunda: Introduction to Thermocouples
		The Thermocouple is a thermoelectric temperature sensor which consists of two dissimilar metallic wires, e.g., one chromel and one constantan, coupled at the probe tip (measurement junction) and extended to the reference (known temperature) junction.
		The temperature difference between the probe tip and the reference junction is detected by measuring the change in voltage (electromotive force, EMF) at the reference junction.
		Common commercially available thermocouples are specified by ISA (Instrument Society of America) types.
	www.efunda.com /designstandards/sensors/thermocouples/thmcple_intro.cfm (309 words)

	Thermocouple Contacts are used with D-subminiature connectors., Positronic Industri
		Type K, T, and E thermocouple contacts can be mixed with signal, power, coaxial, and high voltage contacts in single connector package.
		Type K, T, and E thermocouple contacts can now be mixed with signal, power, coax, and high voltage contacts in a single connector package.
		Thermocouple contact are $18.00 per mated pair at 500 pieces with delivery time of stock to six weeks.
	news.thomasnet.com /fullstory/490068/rss (397 words)

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