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Thermocouples

A thermocouple comprises an electrical circuit formed by two metal conductors of different metals soldered together at the ends. When there is a difference in temperature between the two joints, due to the Seebeck effect, a loop of current is generated and then, if one of the two joints is opened, an electromotive force (emf).
The polarization and intensity of the electromotive force depends solely on the type of metals used and the temperature to which the joints are subjected.
The joint exposed to the temperature to be measured is called the hot junction or the measuring junction while the joint between the thermocouple conductors and the measuring circuit is called the cold junction or the reference junction.
To measure a temperature with a thermocouple the reference junction must be at a given temperature (normally 0°) so that the emf generated depends solely on the temperature of the measuring junction. The type of thermocouple depends on the materials comprising the conductors which can be summarized as follows:

Type Temperature limits (°C) Descriptions
Symbol Materials
S Pt10%Rh - Pt -50 / 1760 Thermocouples composed of noble metals (Platinum and Rhodium) enable very precise measurements to be obtained. Especially resistant at high temperatures, it is generally used in oxidizing atmospheres. It is not really recommended in reducing atmospheres or those containing metal gases.
R Pt13%Rh - Pt -50 / 1760 Like the "S" type thermocouple but with different percentages of the two metals.
B Pt30%Rh - Pt6%Rh 0 / 1820 Thermocouple composed of noble metals which, due to a greater quantity of Rhodium than the "S" and "R" types, is more resistant at high temperatures and to mechanical stress.
E Cr - Co -270 / 1000 Thermocouple with high thermoelectrical power which combines the positive pole of the "K" type thermocouple and the negative pole of the "J" type thermocouple.
Particularly indicated in oxidizing atmospheres.
J Fe - Co -210 / 1200 Thermocouple comprising an iron positive pole and a constantan (copper-nickel alloy) negative pole. Indicated for measuring medium temperatures in reducing atmospheres and with the presence of hydrogen and carbon.
The presence of iron jeopardizes its working properly in oxidizing atmospheres.
K Cr - Al -270 / 1370 Thermocouple composed of alloys containing nickel. It is suitable for measuring high temperatures in oxidizing atmospheres. Not to be used in reducing atmospheres.
T Cu - Co -270 / 400 Thermocouple which permits accurate measurements at low temperatures in oxidizing and reducing atmospheres.
N Nicrosil - Nisil -270 / 400 (1)
0 / 1300 (2)		 Thermocouple for high temperatures similar to type "K" but with less hysteresis.
W3 W3%Re- W25%Re 0 / 2310 Thermocouple for extremely high temperatures comprising a Tungsten positive pole containing 3% rhenium and a Tungsten negative pole containing 25% rhenium.
Particularly resistant in reducing atmospheres and in the presence of hydrogen or other inert gases.
Not to be used in air or oxidizing atmospheres.
W5 W5%Re - W26%Re 0 / 2310 Thermocouple very similar to W3 but with a greater percentage of rhenium which increases its mechanical resistance. Other characteristics are identical to those of the W3 thermocouple.

(1) Thermocouple with 0.32 mm diameter wires
(2) Thermocouple with 1.63 mm diameter wires

The methods for carrying out measurements with thermocouples can generally be divided into two types.

The first, as shown in figure No. 1, is generally used in industrial fields where extreme precision is not necessary

In this case the thermocouple is connected directly (fig. 1a) to the measuring device using compensated or extension cables (fig. 1b).

In this case the compensation of the reference junction is carried out directly by the measuring device which, measuring the junction temperature with other types of sensors, electronically modifies the thermocouple signal so that it is only dependent on the temperature of the measuring junction and thus the temperature to be measured.

The second type enables highly accurate measurements to be obtained and for this reason is used almost exclusively in laboratory applications.

In this case the temperature of the reference junction is maintained at a given and constant temperature (normally the melting point of ice 0°C) through manual or automatic procedures in order to compensate the electromotive force measured by the measuring device with that corresponding to the measuring junction.

As in the case of resistance thermometers, there are also basically two construction types of thermocouples:
with traditional insulation and with mineral insulation.
The following table shows the main characteristics of the two construction types

  Response speed Electrical Insulation Resistance to vibrations Resistance to pressure
Traditional Insulation Sufficient Good Sufficient Good
Mineral Insulation (MgO) Excellent Good Excellent Excellent

Traditional insulation thermocouples comprise:

  1. Measuring junction
    The measuring junction or hot junction is the area in which the two conductors of the thermocouple are joined together; since its dimensions are small, we can consider the measurement carried out with the thermocouples to be punctiform. This junction must be created in such a way that there is no mechanical stress on the two conductors (especially as regards thermocouples made of noble metals) as, once at temperature, this would jeopardize the correct functioning of the thermocouple.
  2. Thermocouple wires
    The wires of the thermocouple must be of appropriate dimensions for the conditions of use; it is possible to insert two or more thermocouples into the same probe.
  3. Ceramic insulators
    Ceramic insulators are used to keep the thermocouple wires insulated along the entire length of the probe both from each other and the external sheath.
  4. Protective sheath
    The protective sheath is designed to protect the thermocouple wires. Since it is in contact with the process, it is important that it is made of the right material and has the right dimensions.
    The protective sheath is normally made of metal however it can be made of ceramic in the case of very high temperatures. In certain conditions is it advisable to cover the sheath with a further protective casing (thermowell).
  5. Connection head
    The connection head contains the terminal board made of insulating material (normally ceramic) which permits the electrical connection of the thermocouple. Depending on the conditions of use explosionproof casing may be used.
    A 4-20mA converter can be installed instead of the terminal board.

In traditional insulation thermocouples the limits to the use of the different thermocouples is determined not only by the type of sheath but also by the dimensions of the thermocouple wires as indicated in the table below:

TYPE CONDITIONS WIRE DIAMETER (mm)
3 1,5 1,3 0,8 0,5 0,25
J Bare wires 650 480 480 425 340 310
Sheated wires 760 590 450 480 370 370
K/N Bare wires 1.090 925 925 870 760 700
Sheated wires 1.260 1.090 1.090 980 870 815
T Bare wires 315 315 260 200 200 200
Sheated wires 370 370 315 260 200 200
E Bare wires 760 590 590 480 370 370
Sheated wires 870 650 650 540 425 425
S/R Bare wires 1.540 1.480 1.320
Sheated wires
B Bare wires 1.700
Sheated wires
Temperature limits in °C            

This particular construction type enables the production of high performance thermocouples with excellent mechanical characteristics. The made construction characteristics can be summarized as follows:

  • the possibility of producing extremely small thermocouples (from 0.5mm diameter)
  • the possibility of bending the sheath with a very sharp bending radius
  • the considerable increase in the average life of the thermocouple
  • the possibility of producing very long thermocouples
  1. Measuring junction
    Special techniques are used to create the joint between the two conductors forming the thermocouple inside the mineral oxide insulation cable which is then closed. The measuring junction can be insulated, grounded or exposed (see table).
  2. Thermocouple wires
    Inside the mineral oxide insulation cable there can be two, four or six wires; the thermocouple can thus be simple, double or triple.
  3. Sheath with mineral insulation
    This comprises a metal sheath containing the conductors which are insulated from each other and from the sheath itself by extremely pure and highly compressed metal oxides; standard insulation uses magnesium oxide, MgO.
  4. Connection head
    The connection head contains the terminal board made of insulating material (normally ceramic) which permits the electrical connection of the thermocouple. Depending on the conditions of use explosionproof casing may be used. A 4-20mA converter can be installed instead of the terminal board.

There are three types of measuring junction for mineral insulation thermocouples; the choice depends on the conditions of use of the thermocouple.

  1. Exposed hot junction
    Characterized by very a short response time as it is in direct contact with the environment in which the temperature must be measured; however it is not recommended for use in corrosive environments.
  2. Grounded hot junction
    The measuring junction is an integral part of the protective sheath and consequently the response time is quite short. This junction conforms to the ASTM-E-235 standard. It is recommended where there is high pressure (up to 3500Kg/cm2).
  3. Insulated hot junction
    The hot junction is completely insulated from the protective sheath and is, therefore, particularly indicated in cases where parasitic emf could affect the measurements. This junction conforms to the ASTM-E-235 standard.

The following chart shows the time it takes a mineral insulation thermocouple to reach 63.2% of the thermal head measured in water with a speed of 0.4m/s

The main causes of errors which can occur while measuring the temperature with thermocouples are the following:

  • Connection of thermocouple to the measuring device with an unsuitable cable
  • Inversion of polarity in the connections
  • Parasitic emf
  • Incorrect compensation of the reference junction

All the connections between the thermocouples and the measuring devices must be carried out with suitable compensated cables. There are compensated cables for each type of thermocouple, the choice of type of insulation and dimensions depends solely on the conditions of use (see section on cables).

All compensation and/or extension cables for thermocouples have a color identifying both the type of thermocouple and its polarity. It is, therefore, important to take care not to invert the polarities in any connections.
It is, however, good practice to make as few junctions as possible in connections between thermocouples and measuring instruments and to use the special devices with compensated contacts which prevent polarity inversion.

When using thermocouples with grounded measuring junctions, parasitic emf may be introduced from the thermocouple to the measuring device and, since the thermocouple signal is in mV, it may easily be disturbed or altered.
It is, therefore, advisable to use thermocouples with insulated measuring junctions.

As stated previously measuring with thermocouples requires the compensation of the reference junction; it is important that this be carried out correctly by the measuring device.

Thermocouple type "B" (PtRh30% vs. PtRh6%) acc. to EN 60584-1 (ITS90)

°C 0 10 20 30 40 50 60 70 80 90 °C
FEM thermoelectric voltage in mV
0 0,000 -0,002 -0,003 -0,002 0,000 0,002 0,006 0,011 0,017 0,025 0
100 0,033 0,043 0,053 0,065 0,078 0,092 0,107 0,123 0,141 0,159 100
200 0,178 0,199 0,220 0,243 0,267 0,291 0,317 0,344 0,372 0,401 200
300 0,431 0,462 0,494 0,527 0,561 0,596 0,632 0,669 0,707 0,746 300
400 0,787 0,828 0,870 0,913 0,957 1,002 1,048 1,095 1,143 1,192 400
500 1,242 1,293 1,344 1,397 1,451 1,505 1,561 1,617 1,675 1,733 500
600 1,792 1,852 1,913 1,975 2,037 2,101 2,165 2,230 2,296 2,363 600
700 2,431 2,499 2,569 2,639 2,710 2,782 2,854 2,928 3,002 3,078 700
800 3,154 3,230 3,308 3,386 3,466 3,546 3,626 3,708 3,790 3,873 800
900 3,957 4,041 4,127 4,213 4,299 4,387 4,475 4,564 4,653 4,743 900
1.000 4,834 4,926 5,018 5,111 5,205 5,299 5,394 5,489 5,585 5,682 1.000
1.100 5,780 5,878 5,976 6,075 6,175 6,276 6,377 6,478 6,580 6,683 1.100
1.200 6,786 6,890 6,995 7,100 7,205 7,311 7,417 7,524 7,632 7,740 1.200
1.300 7,848 7,957 8,066 8,176 8,286 8,397 8,508 8,620 8,731 8,844 1.300
1.400 8,956 9,069 9,182 9,296 9,410 9,524 9,639 9,735 9,868 9,984 1.400
1.500 10,099 10,215 10,331 10,447 10,563 10,679 10,796 10,913 11,029 11,146 1.500
1.600 11,263 11,380 11,497 11,614 11,731 11,848 11,965 12,082 12,199 12,316 1.600
1.700 12,433 12,549 12,666 12,782 12,898 13,014 13,130 13,246 13,361 13,476 1.700
1.800 13,591 13,706 13,820               1.800
°C 0 10 20 30 40 50 60 70 80 90 °C

Reference junction at 0°C

Thermocouple type "E" (Cr-Co) acc. to EN 60584-1 (ITS 90)

°C 0 -10 -20 -30 -40 -50 -60 -70 -80 -90 °C
FEM thermoelectric voltage in mV
-200 -8,825 -9,063 -9,274 -9,455 -9,604 -9,718 -9,797 -9,835     -200
-100 -5,237 -5,681 -6,107 -6,516 -6,907 -7,279 -7,632 -7,963 -8,273 -8,561 -100
0 0,000 -0,582 -1,152 -1,709 -2,255 -2,787 -3,306 -3,381 -4,302 -4,777 0
°C 0 10 20 30 40 50 60 70 80 90 °C
FEM thermoelectric voltage in mV
0 0,000 0,591 1,192 1,801 2,420 3,048 3,685 4,330 4,985 5,648 0
100 6,319 6,998 7,685 8,379 9,081 9,789 10,503 11,224 11,951 12,684 100
200 13,421 14,164 14,912 15,664 16,420 17,181 17,945 18,713 19,484 20,259 200
300 21,036 21,817 22,600 23,386 24,174 24,964 25,757 26,552 27,348 28,146 300
400 28,946 29,747 30,550 31,354 32,159 32,965 33,772 34,579 35,387 36,196 400
500 37,005 37,815 38,624 39,434 40,243 41,053 41,862 42,671 43,479 44,286 500
600 45,093 45,900 46,705 47,509 48,313 49,116 49,917 50,718 51,517 52,315 600
700 53,112 53,908 54,703 55,497 56,289 57,080 57,870 58,659 59,446 60,232 700
800 61,017 61,801 62,583 63,364 64,144 64,922 65,698 66,473 67,246 68,017 800
900 68,787 69,554 70,319 71,082 71,844 72,603 73,360 74,115 74,869 75,621 900
1.000 76,373                   1.000
°C 0 10 20 30 40 50 60 70 80 90 °C

Reference junction at 0°C

Thermocouple type "J" (Fe-Co) acc. to EN 60584-1 (ITS 90)

°C 0 -10 -20 -30 -40 -50 -60 -70 -80 -90 °C
FEM thermoelectric voltage in mV
-200 -7,890 -8,095                 -200
-100 -4,633 -5,037 -5,426 -5,801 -6,159 -6,500 -6,821 -7,123 -7,403 -7,659 -100
0 0,000 -0,501 -0,995 -1,482 -1,961 -2,431 -2,893 -3,344 -3,786 -4,215 0
°C 0 10 20 30 40 50 60 70 80 90 °C
FEM thermoelectric voltage in mV
0 0,000 0,507 1,019 1,537 2,059 2,585 3,116 3,650 4,187 4,726 0
100 5,269 5,814 6,360 6,909 7,459 8,010 8,562 9,115 9,669 10,224 100
200 10,779 11,334 11,889 12,445 13,000 13,555 14,110 14,665 15,219 15,773 200
300 16,327 16,881 17,434 17,986 18,538 19,090 19,642 20,194 20,745 21,297 300
400 21,848 22,400 22,952 23,504 24,057 24,610 25,164 25,720 26,276 26,834 400
500 27,393 27,953 28,516 29,080 29,647 30,216 30,788 31,362 31,939 32,519 500
600 33,102 33,689 34,279 34,873 35,470 36,071 36,675 37,284 37,896 38,512 600
700 39,132 39,755 40,382 41,012 41,645 42,281 42,919 43,559 44,203 44,848 700
800 45,494 46,141 46,786 47,431 48,074 48,715 49,353 49,989 50,622 51,251 800
900 51,877 52,500 53,119 53,735 54,347 54,956 55,561 56,164 56,763 57,360 900
1.000 57,953 58,545 59,134 59,721 60,307 60,890 61,473 62,054 62,634 63,214 1.000
1.100 63,792 64,370 64,948 65,525 66,102 66,679 67,255 67,831 68,406 68,980 1.100
1.200 69,553                   1.200
°C 0 10 20 30 40 50 60 70 80 90 °C

Reference junction at 0°C

Thermocouple type "K" (Cr-Al) acc. to EN 60584-1 (ITS 90)

°C 0 -10 -20 -30 -40 -50 -60 -70 -80 -90 °C
FEM thermoelectric voltage in mV
-200 -5,891 -6,035 -6,158 -6,262 -6,344 -6,404 -6,441 -6,458     -200
-100 -3,554 -3,852 -4,138 -4,411 -4,669 -4,913 -5,141 -5,354 -5,550 -5,730 -100
0 0,000 -0,392 -0,778 -1,156 -1,527 -1,889 -2,243 -2,587 -2,920 -3,243 0
°C 0 10 20 30 40 50 60 70 80 90 °C
FEM thermoelectric voltage in mV
0 0,000 0,397 0,798 1,203 1,612 2,023 2,436 2,851 3,267 3,682 0
100 4,096 4,509 4,920 5,328 5,735 6,138 6,540 6,941 7,340 7,739 100
200 8,138 8,539 8,940 9,343 9,747 10,153 10,561 10,971 11,382 11,795 200
300 12,209 12,624 13,040 13,457 13,874 14,293 14,713 15,133 15,554 15,975 300
400 16,397 16,820 17,243 17,667 18,091 18,516 18,941 19,366 19,792 20,218 400
500 20,644 21,071 21,497 21,924 22,350 22,776 23,203 23,629 24,055 24,480 500
600 24,905 25,330 25,755 26,179 26,602 27,025 27,447 27,869 28,289 28,710 600
700 29,129 29,548 29,965 30,382 30,798 31,213 31,628 32,041 32,453 32,865 700
800 33,275 33,685 34,093 34,501 34,908 35,313 35,718 36,121 36,524 36,925 800
900 37,326 37,725 38,124 38,522 38,918 39,314 39,708 10,101 40,490 40,885 900
1.000 41,276 41,665 42,053 42,440 42,826 43,211 43,595 43,978 44,359 44,740 1.000
1.100 45,119 45,497 45,873 46,249 46,623 46,995 47,367 47,737 48,105 48,473 1.100
1.200 48,838 49,202 49,565 49,926 50,286 50,644 51,000 51,355 51,708 52,060 1.200
1.300 52,410 52,759 53,106 53,451 53,795 54,138 54,479 54,819     1.300
°C 0 10 20 30 40 50 60 70 80 90 °C

Reference junction at 0°C

Thermocouple type "N" (Nicrosil - Nisil) acc. to EN 60584-1 (ITS 90)

°C 0 -10 -20 -30 -40 -50 -60 -70 -80 -90 °C
FEM thermoelectric voltage in mV
-200 -3,990 -4,083 -4,162 -4,226 -4,313 -4,336 -4,345       -200
-100 -2,407 -2,612 -2,808 -2,994 -3,171 -3,336 -3,491 -3,634 -3,766 -3,884 -100
0 0,000 -0,260 -0,518 -0,772 -1,023 -1,269 -1,509 -1,744 -1,972 -2,193 0
°C 0 10 20 30 40 50 60 70 80 90 °C
FEM thermoelectric voltage in mV
0 0,000 0,261 0,525 0,793 1,065 1,340 1,619 1,902 2,189 2,480 0
100 2,774 3,072 3,374 3,680 3,989 4,302 4,618 4,937 5,259 5,585 100
200 5,913 6,245 6,579 6,916 7,255 7,597 7,941 8,288 8,637 8,988 200
300 9,341 9,696 10,054 10,413 10,774 11,136 11,501 11,867 12,234 12,603 300
400 12,974 13,346 13,719 14,094 14,469 14,846 15,225 15,604 15,984 16,366 400
500 16,748 17,131 17,515 17,900 18,286 18,672 19,059 19,447 19,835 20,224 500
600 20,613 21,003 21,393 21,784 22,175 22,566 22,958 23,350 23,742 24,134 600
700 24,527 24,919 25,312 25,705 26,098 26,491 26,883 27,276 27,669 28,062 700
800 28,455 28,847 29,239 29,632 30,024 30,416 30,807 31,199 31,590 31,981 800
900 32,371 32,761 33,151 33,541 33,930 34,319 34,707 35,095 35,482 35,869 900
1.000 36,256 36,641 37,027 37,411 37,795 38,179 38,562 38,944 39,326 39,706 1.000
1.100 40,087 40,466 40,845 41,223 41,600 41,976 42,352 42,727 43,101 43,474 1.100
1.200 43,846 44,218 44,588 44,958 45,326 45,694 46,606 46,425 46,789 47,152 1.200
1.300 47,513                   1.300
°C 0 10 20 30 40 50 60 70 80 90 °C

Reference junction at 0°C

Thermocouple type "R" (PtRh13% - Pt) acc. to EN 60584-1 (ITS 90)

°C 0 -10 -20 -30 -40 -50 -60 -70 -80 -90 °C
FEM thermoelectric voltage in mV
0 0,000 -0,051 -0,100 -0,145 -0,188 -0,226         0
°C 0 10 20 30 40 50 60 70 80 90 °C
FEM thermoelectric voltage in mV
0 0,000 0,054 0,111 0,171 0,232 0,296 0,363 0,431 0,501 0,573 0
100 0,647 0,723 0,800 0,879 0,959 1,041 1,124 1,208 1,294 1,381 100
200 1,469 1,558 1,648 1,739 1,831 1,923 2,017 2,112 2,207 2,304 200
300 2,401 2,498 2,597 2,696 2,796 2,896 2,997 3,099 3,201 3,304 300
400 3,408 3,512 3,616 3,721 3,827 3,933 4,040 4,147 4,255 4,363 400
500 4,471 4,580 4,690 4,800 4,910 5,021 5,133 5,245 5,357 5,470 500
600 5,583 5,697 5,812 5,926 6,041 6,157 6,237 6,390 6,507 6,625 600
700 6,743 6,861 6,980 7,100 7,220 7,340 7,461 7,583 7,705 7,827 700
800 7,950 8,073 8,197 8,321 8,446 8,571 8,697 8,823 8,950 9,077 800
900 9,205 9,333 9,461 9,590 9,720 9,850 9,980 10,111 10,242 10,374 900
1.000 10,506 10,638 10,771 10,905 11,039 11,173 11,307 11,442 11,578 11,714 1.000
1.100 11,850 11,986 12,123 12,260 12,397 12,535 12,673 12,812 12,950 13,089 1.100
1.200 13,228 13,367 13,507 13,646 13,786 13,926 14,066 14,207 14,347 14,488 1.200
1.300 14,629 14,770 14,911 15,052 15,193 15,334 15,475 15,616 15,758 15,899 1.300
1.400 16,040 16,181 16,323 16,464 16,605 16,746 16,887 17,028 17,169 17,310 1.400
1.500 17,451 17,591 17,732 17,872 18,012 18,152 18,292 18,431 18,571 18,710 1.500
1.600 18,849 18,988 19,126 19,264 19,402 19,540 19,677 19,814 19,951 20,087 1.600
1.700 20,222 20,356 20,488 20,620 20,749 20,877 21,003       1.700
°C 0 10 20 30 40 50 60 70 80 90 °C

Reference junction at 0°C

Thermocouple type "S" (PtRh10% - Pt) acc. to EN 60584-1 (ITS 90)

°C 0 -10 -20 -30 -40 -50 -60 -70 -80 -90 °C
FEM thermoelectric voltage in mV
0 0,000 -0,053 -0,103 -0,150 -0,194 -0,236         0
°C 0 10 20 30 40 50 60 70 80 90 °C
FEM thermoelectric voltage in mV
0 0,000 0,055 0,113 0,173 0,235 0,299 0,365 0,433 0,502 0,573 0
100 0,646 0,720 0,795 0,872 0,950 1,029 1,110 1,191 1,273 1,357 100
200 1,441 1,526 1,612 1,698 1,786 1,874 1,962 2,052 2,141 2,232 200
300 2,323 2,415 2,507 2,599 2,692 2,786 2,880 2,974 3,096 3,164 300
400 3,259 3,355 3,451 3,548 3,645 3,742 3,840 3,938 4,036 3,134 400
500 4,233 4,332 4,432 4,532 4,632 4,732 4,833 4,934 5,035 5,137 500
600 5,239 5,341 5,443 5,546 5,659 5,753 5,857 5,961 6,065 6,170 600
700 6,275 6,381 6,486 6,593 6,699 6,806 6,913 7,020 7,128 7,236 700
800 7,345 7,454 7,563 7,673 7,783 7,893 8,003 8,114 8,226 8,337 800
900 8,449 8,562 8,674 8,787 8,900 9,014 9,128 9,242 9,357 9,472 900
1.000 9,587 9,703 9,819 9,935 10,051 10,168 10,285 10,403 10,520 10,638 1.000
1.100 10,757 10,875 10,994 11,113 11,232 11,351 11,471 11,590 11,710 11,830 1.100
1.200 11,951 12,071 12,191 12,312 12,433 12,554 12,675 12,796 12,917 13,038 1.200
1.300 13,159 13,280 13,402 13,523 13,644 13,766 13,887 14,009 14,130 14,251 1.300
1.400 14,373 14,494 14,615 14,736 14,857 14,978 15,099 15,220 15,341 15,461 1.400
1.500 15,582 15,702 15,822 15,942 16,062 16,182 16,301 16,420 16,539 16,658 1.500
1.600 16,777 16,895 17,013 17,131 17,249 17,366 17,483 17,600 17,717 17,832 1.600
1.700 17,947 18,061 18,174 18,825 18,395 18,503 18,609       1.700
°C 0 10 20 30 40 50 60 70 80 90 °C

Reference junction at 0°C

Thermocouple type "T" (Cu-Co) acc. to EN 60584-1 (ITS 90)

°C 0 -10 -20 -30 -40 -50 -60 -70 -80 -90 °C
FEM thermoelectric voltage in mV
-200 -5,603 -5,753 -5,888 -6,007 -6,105 -6,180 -6,232 -6,258     -200
-100 -3,379 -3,657 -3,923 -4,177 -4,419 -4,648 -4,865 -5,070 -5,261 -5,439 -100
0 0,000 -0,383 -0,757 -1,121 -1,475 -1,819 -2,153 -2,476 -2,788 -3,089 0
°C 0 10 20 30 40 50 60 70 80 90 °C
FEM thermoelectric voltage in mV
0 0,000 0,391 0,790 1,196 1,612 2,036 2,468 2,909 3,358 3,814 0
100 4,279 4,750 5,228 5,714 6,206 6,704 7,209 7,720 8,237 8,759 100
200 9,288 9,822 10,362 10,907 11,458 12,013 12,574 13,139 13,709 14,283 200
300 14,862 15,445 16,032 16,624 17,219 17,819 18,422 19,030 19,641 20,255 300
400 20,872                   400

Reference junction at 0°C

TYPE JIS C 1602 ANSI MC 96.1 DIN 43710 EN 60584-2
Temp. range (°C) Grade Tolerance (°C) Temp. range (°C) Grade Tolerance (°C) Temp. range (°C) Tolerance (°C) Temp. range (°C) Grade Tolerance (°C)
B +200+1700 0.5 ± 4°C or ± 0.5% +800+1700 STD ± 0.5% - - +600+1700 2 ± 0.0025*|t|
3 ± 4°C or ± 0.005* |t|
R 0+1600 0.25 ± 1.5°C or ± 0.25% 0+1450 STD ± 1,5°C or ± 0,25% 0+600 ± 3°C 0-1600 1 ± 1°C or ± [1+0.003 * (T-1100)]°C
SPC ± 0,6°C or ± 0,1% +600+1600 ± 5°C 2 ± 1,5°C or ± 0.0025 * |t|
S 0+1600 0.25 ± 1.5°C or ± 0.25% 0+1450 STD ± 1,5°C or ± 0,25% 0-600 ± 3°C 0-1600 1 ± 1°C or ± [1+0.003 * (T-1100)]°C
SPC ± 0,6°C or ± 0,1% 600-1600 ± 5°C 2 ± 1,5°C or ± 0.0025* |t|
K 0+1000 0.4 ± 1.5°C or ± 0.4% 0+1250 STD ± 2.2°C or ± 0.75% 0+400 ± 3°C -40+1000 1 ± 1,5°C or ± 0.004* |t|
400+1200 ± 0.75°C
0+1200 0.75 ± 2.5°C or ± 0.75% SPC ± 1.1°C or ± 0.40% -40+1200 2 ± 2,5°C or ± 0.0075* |t|
-200-0 1.5 ± 2.5°C or ± 1.5% -200-0 STD ± 2.2°C or ± 2% -200+40 3 ± 2,5°C or ± 0.015* |t|
N 0+1000 0.25 ± 1.5°C or ± 0.4% 0+1250 STD ± 2.2°C or ± 0.75% - - -40+1000 1 ± 1,5°C or ± 0.004* |t|
0+1200 0.75 ± 2.5°C or ± 0.75% SPC ± 1.1°C or ± 0.40% -40+1200 2 ± 2,5°C or ± 0.0075* |t|
-200-0 1.5 ± 2.5°C or ± 1.5% -200-0 STD ± 2.2°C or ± 2% -200+40 3 ± 2,5°C or ± 0.015* |t|
E 0+800 0.4 ± 1.5°C or ± 0.4% 0+900 STD ± 1,7°C or ± 0.50% - - -40-800 1 ± 1,5°C or ± 0.004* |t|
0.75 ± 2.5°C or ± 0.75% SPC ± 1°C or ± 0.40% -40-900 2 ± 2,5°C or ± 0.0075* |t|
-200-0 1.5 ± 2.5°C or ± 1.5% -200-0 STD ± 1.7°C or ± 1% -200-40 3 ± 2,5°C or ± 0.015* |t|
J 0+750 0.4 ± 1.5°C or ± 0.4% 0+750 STD ± 2.2°C or ± 0.75% 0.400 ± 3°C -40+750 1 ± 1,5°C or ± 0.004* |t|
0.75 ± 2.5°C or ± 0.75% SPC ± 1.1°C or ± 0.4% 400+900 ± 0.75° 2 ± 2,5°C or ± 0.0075* |t|
T 0+350 0.4 ± 0.5°C or ± 0.4% 0+350 STD ± 0.5°C or ± 0.4% -200+400 ± 3°C -40+350 1 ± 0,5°C or ± 0.004* |t|
0.75 ± 1°C or ± 0.75% SPC ± 1°C or ± 0.75% 2 ± 1°C or ± 0.0075* |t|
-200-0 1.5 ± 1°C or ± 1.5% -200-0 STD ± 1°C or ± 1.5% -200+40 3 ± 1°C or ± 0.015* |t|