IEC 60751:2008
(Main)Industrial platinum resistance thermometers and platinum temperature sensors
Industrial platinum resistance thermometers and platinum temperature sensors
IEC 60751:2008 specifies the requirements and temperature/resistance relationship for industrial platinum resistance temperature sensors later referred to as "platinum resistors" or "resistors" and industrial platinum resistance thermometers later referred to as "thermometers" whose electrical resistance is a defined function of temperature. Values of temperature in this standard are in terms of the International Temperature Scale of 1990, ITS-90. Temperatures in degrees Celsius are denoted by the symbol t, except in Table 1 where the full nomenclature t90/°C is used. The standard covers resistors or thermometers for all or part of the temperature range 200 °C to +850 °C with different tolerance classes, which may cover restricted temperature ranges. This second edition cancels and replaces the first edition published in 1983, amendment 1 (1986) and amendment 2 (1995). It constitutes a technical revision. The significant technical changes with respect to the previous edition are as follows: While the temperature/resistance relationship in 4.2 remains unchanged, there are several changes in the other chapters. Most important are: tolerance classes follow a new scheme; tolerance acceptance test is included; hysteresis test is included; several changes in the individual tests; appendices are deleted.
Thermomètres à résistance de platine industriels et capteurs thermométriques en platine
La CEI 60751:2008 spécifie les exigences et la relation température/résistance pour les capteurs à résistance de platine industriels, dénommés ci-après "résistances de platine" ou "résistances", et les thermomètres à résistance de platine industriels, dénommés ci-après "thermomètres", dont la résistance électrique est une fonction définie de la température. Les valeurs de température données dans la présente norme sont exprimées en accord avec l'Echelle Internationale de Température de 1990, EIT-90, en degrés Celsius, et par le symbole t, à l'exception du Tableau 1 où l'expression t90/°C est utilisée. Elle couvre les résistances ou thermomètres pour toutes les parties de la gamme -200 °C à +850 °C avec différentes classes de tolérance, qui peuvent couvrir des domaines de températures limités. Cette deuxième édition annule et remplace la première édition parue en 1983, l'amendement1 (1986) et l'amendement 2 (1995). Cette édition constitue une révision technique. Par rapport à l'édition précédente, les modifications techniques majeures sont les suivantes: Alors que la relation entre la température et la résistance, donnée en 4.2 est inchangée, plusieurs modifications sont apportées dans les autres chapitres. Les plus importants sont: les classes de tolérance suivent un nouveau système; un essai d'acceptation de la tolérance est inclus; un essai d'hystérésis est inclus; plusieurs modifications sont apportées dans les essais individuels; des appendices sont supprimés.
General Information
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Standards Content (Sample)
IEC 60751
Edition 2.0 2008-07
INTERNATIONAL
STANDARD
NORME
INTERNATIONALE
Industrial platinum resistance thermometers and platinum temperature sensors
Thermomètres à résistance de platine industriels et capteurs thermométriques
en platine
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IEC 60751
Edition 2.0 2008-07
INTERNATIONAL
STANDARD
NORME
INTERNATIONALE
Industrial platinum resistance thermometers and platinum temperature sensors
Thermomètres à résistance de platine industriels et capteurs thermométriques
en platine
INTERNATIONAL
ELECTROTECHNICAL
COMMISSION
COMMISSION
ELECTROTECHNIQUE
PRICE CODE
INTERNATIONALE
S
CODE PRIX
ICS 17.200.20 ISBN 2-8318-9849-8
– 2 – 60751 © IEC:2008
CONTENTS
FOREWORD.4
1 Scope.6
2 Normative references .6
3 Terms and definitions .6
4 Characteristics .8
4.1 Temperature/resistance relationships .8
4.2 Resistance values .9
5 General requirements .12
5.1 Tolerance classes .12
5.1.1 Temperature range of validity .12
5.1.2 Resistors .12
5.1.3 Thermometers .12
5.1.4 Special tolerance classes and special temperature ranges of validity .12
5.2 Measuring current .13
5.3 Electrical supply .13
5.4 Connecting wire configuration .13
6 Tests .14
6.1 General .14
6.1.1 Routine production tests.14
6.1.2 Type tests .14
6.1.3 Additional type tests .14
6.2 Routine production tests for resistors .14
6.2.1 Tolerance acceptance test.14
6.3 Routine production tests for thermometers .15
6.3.1 Insulation resistance at ambient temperature.15
6.3.2 Sheath integrity test .15
6.3.3 Dimensional test.16
6.3.4 Tolerance acceptance test.16
6.4 Type tests for resistors.16
6.4.1 Tolerances .16
6.4.2 Stability at upper temperature limit .16
6.4.3 Self-heating.16
6.5 Type tests for thermometers.16
6.5.1 Insulation resistance at elevated temperatures .16
6.5.2 Thermal response time .18
6.5.3 Stability at upper temperature limit .18
6.5.4 Thermoelectric effect .18
6.5.5 Effect of temperature cycling .18
6.5.6 Effect of hysteresis .18
6.5.7 Self-heating.18
6.5.8 Minimum immersion depth .19
6.6 Additional type tests for special applications of thermometers .19
6.6.1 Capacitance .19
6.6.2 Inductance.19
6.6.3 Dielectric strength .19
6.6.4 Vibration test .19
60751 © IEC:2008 – 3 –
6.6.5 Drop test .19
6.7 Summary of tests .19
7 Information to be made available by the manufacturer.20
7.1 For resistors only .20
7.2 For resistors and/or thermometers.20
8 Thermometer identification and marking .20
Figure 1 – Connecting configurations.13
Figure 2 – Examples of test results for selecting or rejecting resistors. .15
Table 1 – Temperature/resistance relationship, R = 100.00 Ω .10
Table 2 – Tolerance classes for resistors.12
Table 3 – Tolerance classes for thermometers.12
Table 4 – Minimum insulation resistance of thermometers at maximum temperature.16
Table 5 – Table of tests described in this standard .20
– 4 – 60751 © IEC:2008
INTERNATIONAL ELECTROTECHNICAL COMMISSION
____________
INDUSTRIAL PLATINUM RESISTANCE THERMOMETERS AND
PLATINUM TEMPERATURE SENSORS
FOREWORD
1) The International Electrotechnical Commission (IEC) is a worldwide organization for standardization comprising
all national electrotechnical committees (IEC National Committees). The object of IEC is to promote
international co-operation on all questions concerning standardization in the electrical and electronic fields. To
this end and in addition to other activities, IEC publishes International Standards, Technical Specifications,
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Publication(s)”). Their preparation is entrusted to technical committees; any IEC National Committee interested
in the subject dealt with may participate in this preparatory work. International, governmental and non-
governmental organizations liaising with the IEC also participate in this preparation. IEC collaborates closely
with the International Organization for Standardization (ISO) in accordance with conditions determined by
agreement between the two organizations.
2) The formal decisions or agreements of IEC on technical matters express, as nearly as possible, an international
consensus of opinion on the relevant subjects since each technical committee has representation from all
interested IEC National Committees.
3) IEC Publications have the form of recommendations for international use and are accepted by IEC National
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between any IEC Publication and the corresponding national or regional publication shall be clearly indicated in
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Publications.
8) Attention is drawn to the Normative references cited in this publication. Use of the referenced publications is
indispensable for the correct application of this publication.
9) Attention is drawn to the possibility that some of the elements of this IEC Publication may be the subject of
patent rights. IEC shall not be held responsible for identifying any or all such patent rights.
International Standard IEC 60751 has been prepared by subcommittee 65B: Devices and
process analysis, of IEC technical committee 65: Industrial-process measurement, control and
automation.
This second edition cancels and replaces the first edition published in 1983, amendment 1
(1986) and amendment 2 (1995). This edition constitutes a technical revision.
The significant technical changes with respect to the previous edition are as follows:
While the temperature/resistance relationship in 4.2 remains unchanged, there are several
changes in the other chapters. Most important are:
– tolerance classes follow a new scheme;
– tolerance acceptance test is included;
– hysteresis test is included;
– several changes in the individual tests;
– appendices are deleted.
60751 © IEC:2008 – 5 –
The text of this standard is based on the following documents:
FDIS Report on voting
65B/664/FDIS 65B/683/RVD
Full information on the voting for the approval of this standard can be found in the report on
voting indicated in the above table.
This publication has been drafted in accordance with the ISO/IEC Directives, Part 2.
The committee has decided that the contents of this publication will remain unchanged until
the maintenance result date indicated on the IEC web site under "http://webstore.iec.ch" in
the data related to the specific publication. At this date, the publication will be
• reconfirmed,
• withdrawn,
• replaced by a revised edition, or
• amended.
– 6 – 60751 © IEC:2008
INDUSTRIAL PLATINUM RESISTANCE THERMOMETERS AND
PLATINUM TEMPERATURE SENSORS
1 Scope
This standard specifies the requirements and temperature/resistance relationship for
industrial platinum resistance temperature sensors later referred to as “platinum resistors” or
"resistors" and industrial platinum resistance thermometers later referred to as
"thermometers" whose electrical resistance is a defined function of temperature.
The International Standard applies to platinum resistors whose temperature coefficient α,
defined as
R − R
100 0
α =
R ⋅100°C
–3 –1
is conventionally written as α = 3.851 x 10 °C , where R is the resistance at t = 100 °C
and R is the resistance at t = 0 °C.
Values of temperature in this standard are in terms of the International Temperature Scale of
1990, ITS-90. Temperatures in degrees Celsius are denoted by the symbol t, except in
Table 1 where the full nomenclature t /°C is used.
The standard covers resistors or thermometers for all or part of the temperature range
-200 °C to +850 °C with different tolerance classes, which may cover restricted temperature
ranges.
For temperature/resistance relationships with uncertainties <0,1 °C, which are possible only
for resistors or thermometers with exceptionally high stability and individual calibration, a
more complex interpolation equation than is presented in this standard may be necessary.
The specification of such equations is outside the scope of this standard.
2 Normative references
The following referenced documents are indispensable for the application of this document.
For dated references, only the edition cited applies. For undated references, the latest edition
of the referenced document (including any amendments) applies:.
IEC 61152, Dimensions of metal-sheathed thermometer elements
IEC 61298-1, Process Measurement and Control devices – General Methods and Procedures
for Evaluating Performance – Part 1: General considerations
3 Terms and definitions
For the purposes of this document, the following terms and definitions apply.
3.1
dielectric strength
maximum voltage between all parts of the electric circuit and the sheath of the thermometer
or, in the case of a thermometer with two or more sensing circuits, between two individual
60751 © IEC:2008 – 7 –
circuits which the thermometer can withstand without damage. The measurement conditions
for d.c and a.c (with frequency) have to be specified.
3.2
insulation resistance
electrical resistance measured between any part of the electric circuit and the sheath at
ambient or elevated temperatures and with a specified measuring voltage (a.c or d.c)
3.3
minimum immersion depth
immersion depth at which the change from the calibration at full immersion does not exceed
0.1 °C
3.4
nominal resistance
expected resistance R of a resistor or resistance thermometer at 0 °C, declared by the
manufacturer and shown in the thermometer marking, usually rounded to the nearest ohm.
Platinum resistors are often characterized by their nominal: A Pt-100 resistor is a resistor with
R = 100 Ω
3.5
platinum resistance thermometer
PRT
temperature responsive device consisting of one or more sensing platinum resistors within a
protective sheath, internal connecting wires and external terminals to permit connection of
electrical measurement instruments. Mounting means and connection heads may be included.
Not included is any separable protection tube or thermowell
3.6
temperature sensitive length
length of the thermometer whose temperature directly influences the resistance measured.
Usually the temperature sensitive length is related to the length of the resistor
3.7
platinum resistor
resistor made from a platinum wire or film with defined electrical characteristics, embedded in
an insulator (in most cases glass or ceramic), designed to be assembled into a resistance
thermometer or into an integrated circuit
3.8
self-heating
increase of the temperature of the resistor or of the resistor in a thermometer caused by the
dissipated energy of the measuring current
3.9
self-heating coefficient
coefficient with the dimension °C/mW is characteristic for a resistor/thermometer and
describes the temperature increase of the resistor per unit power dissipated. This coefficient
is evaluated under specified operating conditions of the resistor or thermometer. The medium,
its flow conditions and temperature should be specified
3.10
terminals
termination of the connections supplied with the resistance thermometer
NOTE Typical types of terminals are:
− screws or clamps on the terminal socket;
– 8 – 60751 © IEC:2008
− pins of fixed connectors;
− open ends of fixed cables, or equivalents.
3.11
thermal response time
time a thermometer takes to respond at a specified percentage to a step change in
temperature. To specify the response time, it is necessary to declare the percentage of
response, usually τ , τ , or τ , which gives the time for 90 %, 50 % or 10 % of the
0.9 0.5 0.1
response. The test medium and its flow conditions have to be specified (usually flowing water
and/or flowing air)
3.12
thermoelectric effect
effect of inducing the electro-motive force (EMF) caused by different metals used in the
electric circuit of the thermometer and by thermoelectric inhomogeneity of the internal leads
at the conditions of temperature gradients along the leads. The induced EMF is measured
across the terminals of the thermometer while the thermometer is subjected to a specified
temperature
3.13
tolerance
initial maximum allowable deviation expressed as Δt(t) in °C from the nominal
temperature/resistance relationship R(t)
3.14
hysteresis
property of a device or instrument whereby it gives different output values in relation to its
input values depending on the directional sequence in which the input values have been
applied
[IEC 61298-1, 3.13]
NOTE Hysteresis as defined in IEC 61298-1 can be applied to thermometers by the method described in 6.5.6 of
this standard
4 Characteristics
The temperature/resistance relationships and tolerances in this chapter are valid for the
sensing resistors at its connecting points. For thermometers, they are valid for the complete
thermometer at its terminals.
In the case of two-wire connections, the resistance values of the leads between the
connecting point of the resistor and the terminals shall be considered. They may be indicated
on the thermometer and shall be subtracted from measured resistances. In some cases, it
also may be advisable to consider the temperature coefficient of the lead wires, the
geometrical characteristics of the wires and the temperature distribution along their length.
4.1 Temperature/resistance relationships
The temperature/resistance relationships used in this standard are as follows:
For the range –200 °C to 0 °C:
2 3
R = R [1 + At + Bt + C(t - 100°C) t ]
t 0
For the range of 0 °C to 850 °C:
—————————
First calibration before any use of the resistor or thermometer.
60751 © IEC:2008 – 9 –
R = R (1 + At + Bt )
t 0
where
R is the resistance at the temperature t;
t
R is the resistance at t = 0 °C.
The constants in these equations are:
–3 –1
A = 3.9083 × 10 °C
–7 –2
B = −5.775 × 10 °C
–12 –4
C = −4.183 × 10 °C
These equations and coefficients have been used to derive the table of resistance values,
Table 1, for a platinum resistor of nominal resistance R = 100 Ω .
4.2 Resistance values
The temperature/resistance relationship in Table 1 is given for a resistor with nominal
resistance of 100 Ω. For other nominal resistances R such as; 10 Ω, 500 Ω or 1 000 Ω, the
0,
table can be used by multiplying the table values with the factor R /100 Ω.
– 10 – 60751 © IEC:2008
Table 1 – Temperature/resistance relationship, R = 100.00 Ω
t /°C Resistance at the temperature t /°C t /°C
90 90 90
Ω
0 -1 -2 -3 -4 -5 -6 -7 -8 -9
-200 18.52 -200
-190 22.83 22.40 21.97 21.54 21.11 20.68 20.25 19.82 19.38 18.95 -190
-180 27.10 26.67 26.24 25.82 25.39 24.97 24.54 24.11 23.68 23.25 -180
-170 31.34 30.91 30.49 30.07 29.64 29.22 28.80 28.37 27.95 27.52 -170
-160 35.54 35.12 34.70 34.28 33.86 33.44 33.02 32.60 32.18 31.76 -160
-150 39.72 39.31 38.89 38.47 38.05 37.64 37.22 36.80 36.38 35.96 -150
-140 43.88 43.46 43.05 42.63 42.22 41.80 41.39 40.97 40.56 40.14 -140
-130 48.00 47.59 47.18 46.77 46.36 45.94 45.53 45.12 44.70 44.29 -130
-120 52.11 51.70 51.29 50.88 50.47 50.06 49.65 49.24 48.83 48.42 -120
-110 56.19 55.79 55.38 54.97 54.56 54.15 53.75 53.34 52.93 52.52 -110
-100 60.26 59.85 59.44 59.04 58.63 58.23 57.82 57.41 57.01 56.60 -100
-90 64.30 63.90 63.49 63.09 62.68 62.28 61.88 61.47 61.07 60.66 -90
-80 68.33 67.92 67.52 67.12 66.72 66.31 65.91 65.51 65.11 64.70 -80
-70 72.33 71.93 71.53 71.13 70.73 70.33 69.93 69.53 69.13 68.73 -70
-60 76.33 75.93 75.53 75.13 74.73 74.33 73.93 73.53 73.13 72.73 -60
-50 80.31 79.91 79.51 79.11 78.72 78.32 77.92 77.52 77.12 76.73 -50
-40 84.27 83.87 83.48 83.08 82.69 82.29 81.89 81.50 81.10 80.70 -40
-30 88.22 87.83 87.43 87.04 86.64 86.25 85.85 85.46 85.06 84.67 -30
-20 92.16 91.77 91.37 90.98 90.59 90.19 89.80 89.40 89.01 88.62 -20
-10 96.09 95.69 95.30 94.91 94.52 94.12 93.73 93.34 92.95 92.55 -10
0 100.00 99.61 99.22 98.83 98.44 98.04 97.65 97.26 96.87 96.48 0
t/°C 0 1 2 3 4 5 6 7 8 9 t /°C
90 90
0 100.00 100.39 100.78 101.17 101.56 101.95 102.34 102.73 103.12 103.51 0
10 103.90 104.29 104.68 105.07 105.46 105.85 106.24 106.63 107.02 107.40 10
20 107.79 108.18 108.57 108.96 109.35 109.73 110.12 110.51 110.90 111.29 20
30 111.67 112.06 112.45 112.83 113.22 113.61 114.00 114.38 114.77 115.15 30
40 115.54 115.93 116.31 116.70 117.08 117.47 117.86 118.24 118.63 119.01 40
50 119.40 119.78 120.17 120.55 120.94 121.32 121.71 122.09 122.47 122.86 50
60 123.24 123.63 124.01 124.39 124.78 125.16 125.54 125.93 126.31 126.69 60
70 127.08 127.46 127.84 128.22 128.61 128.99 129.37 129.75 130.13 130.52 70
80 130.90 131.28 131.66 132.04 132.42 132.80 133.18 133.57 133.95 134.33 80
90 134.71 135.09 135.47 135.85 136.23 136.61 136.99 137.37 137.75 138.13 90
100 138.51 138.88 139.26 139.64 140.02 140.40 140.78 141.16 141.54 141.91 100
110 142.29 142.67 143.05 143.43 143.80 144.18 144.56 144.94 145.31 145.69 110
120 146.07 146.44 146.82 147.20 147.57 147.95 148.33 148.70 149.08 149.46 120
130 149.83 150.21 150.58 150.96 151.33 151.71 152.08 152.46 152.83 153.21 130
140 153.58 153.96 154.33 154.71 155.08 155.46 155.83 156.20 156.58 156.95 140
150 157.33 157.70 158.07 158.45 158.82 159.19 159.56 159.94 160.31 160.68 150
160 161.05 161.43 161.80 162.17 162.54 162.91 163.29 163.66 164.03 164.40 160
170 164.77 165.14 165.51 165.89 166.26 166.63 167.00 167.37 167.74 168.11 170
180 168.48 168.85 169.22 169.59 169.96 170.33 170.70 171.07 171.43 171.80 180
190 172.17 172.54 172.91 173.28 173.65 174.02 174.38 174.75 175.12 175.49 190
200 175.86 176.22 176.59 176.96 177.33 177.69 178.06 178.43 178.79 179.16 200
210 179.53 179.89 180.26 180.63 180.99 181.36 181.72 182.09 182.46 182.82 210
220 183.19 183.55 183.92 184.28 184.65 185.01 185.38 185.74 186.11 186.47 220
230 186.84 187.20 187.56 187.93 188.29 188.66 189.02 189.38 189.75 190.11 230
240 190.47 190.84 191.20 191.56 191.92 192.29 192.65 193.01 193.37 193.74 240
250 194.10 194.46 194.82 195.18 195.55 195.91 196.27 196.63 196.99 197.35 250
260 197.71 198.07 198.43 198.79 199.15 199.51 199.87 200.23 200.59 200.95 260
270 201.31 201.67 202.03 202.39 202.75 203.11 203.47 203.83 204.19 204.55 270
280 204.90 205.26 205.62 205.98 206.34 206.70 207.05 207.41 207.77 208.13 280
290 208.48 208.84 209.20 209.56 209.91 210.27 210.63 210.98 211.34 211.70 290
300 212.05 212.41 212.76 213.12 213.48 213.83 214.19 214.54 214.90 215.25 300
310 215.61 215.96 216.32 216.67 217.03 217.38 217.74 218.09 218.44 218.80 310
320 219.15 219.51 219.86 220.21 220.57 220.92 221.27 221.63 221.98 222.33 320
60751 © IEC:2008 – 11 –
Table 1 (continued)
t /°C Resistance at the temperature t /°C t /°C
90 90 90
Ω
0 1 2 3 4 5 6 7 8 9
330 222.68 223.04 223.39 223.74 224.09 224.45 224.80 225.15 225.50 225.85 330
340 226.21 226.56 226.91 227.26 227.61 227.96 228.31 228.66 229.02 229.37 340
350 229.72 230.07 230.42 230.77 231.12 231.47 231.82 232.17 232.52 232.87 350
360 233.21 233.56 233.91 234.26 234.61 234.96 235.31 235.66 236.00 236.35 360
370 236.70 237.05 237.40 237.74 238.09 238.44 238.79 239.13 239.48 239.83 370
380 240.18 240.52 240.87 241.22 241.56 241.91 242.26 242.60 242.95 243.29 380
390 243.64 243.99 244.33 244.68 245.02 245.37 245.71 246.06 246.40 246.75 390
400 247.09 247.44 247.78 248.13 248.47 248.81 249.16 249.50 249.85 250.19 400
410 250.53 250.88 251.22 251.56 251.91 252.25 252.59 252.93 253.28 253.62 410
420 253.96 254.30 254.65 254.99 255.33 255.67 256.01 256.35 256.70 257.04 420
430 257.38 257.72 258.06 258.40 258.74 259.08 259.42 259.76 260.10 260.44 430
440 260.78 261.12 261.46 261.80 262.14 262.48 262.82 263.16 263.50 263.84 440
450 264.18 264.52 264.86 265.20 265.53 265.87 266.21 266.55 266.89 267.22 450
460 267.56 267.90 268.24 268.57 268.91 269.25 269.59 269.92 270.26 270.60 460
470 270.93 271.27 271.61 271.94 272.28 272.61 272.95 273.29 273.62 273.96 470
480 274.29 274.63 274.96 275.30 275.63 275.97 276.30 276.64 276.97 277.31 480
490 277.64 277.98 278.31 278.64 278.98 279.31 279.64 279.98 280.31 280.64 490
500 280.98 281.31 281.64 281.98 282.31 282.64 282.97 283.31 283.64 283.97 500
510 284.30 284.63 284.97 285.30 285.63 285.96 286.29 286.62 286.95 287.29 510
520 287.62 287.95 288.28 288.61 288.94 289.27 289.60 289.93 290.26 290.59 520
530 290.92 291.25 291.58 291.91 292.24 292.56 292.89 293.22 293.55 293.88 530
540 294.21 294.54 294.86 295.19 295.52 295.85 296.18 296.50 296.83 297.16 540
550 297.49 297.81 298.14 298.47 298.80 299.12 299.45 299.78 300.10 300.43 550
560 300.75 301.08 301.41 301.73 302.06 302.38 302.71 303.03 303.36 303.69 560
570 304.01 304.34 304.66 304.98 305.31 305.63 305.96 306.28 306.61 306.93 570
580 307.25 307.58 307.90 308.23 308.55 308.87 309.20 309.52 309.84 310.16 580
590 310.49 310.81 311.13 311.45 311.78 312.10 312.42 312.74 313.06 313.39 590
600 313.71 314.03 314.35 314.67 314.99 315.31 315.64 315.96 316.28 316.60 600
610 316.92 317.24 317.56 317.88 318.20 318.52 318.84 319.16 319.48 319.80 610
620 320.12 320.43 320.75 321.07 321.39 321.71 322.03 322.35 322.67 322.98 620
630 323.30 323.62 323.94 324.26 324.57 324.89 325.21 325.53 325.84 326.16 630
640 326.48 326.79 327.11 327.43 327.74 328.06 328.38 328.69 329.01 329.32 640
650 329.64 329.96 330.27 330.59 330.90 331.22 331.53 331.85 332.16 332.48 650
660 332.79 333.11 333.42 333.74 334.05 334.36 334.68 334.99 335.31 335.62 660
670 335.93 336.25 336.56 336.87 337.18 337.50 337.81 338.12 338.44 338.75 670
680 339.06 339.37 339.69 340.00 340.31 340.62 340.93 341.24 341.56 341.87 680
690 342.18 342.49 342.80 343.11 343.42 343.73 344.04 344.35 344.66 344.97 690
700 345.28 345.59 345.90 346.21 346.52 346.83 347.14 347.45 347.76 348.07 700
710 348.38 348.69 348.99 349.30 349.61 349.92 350.23 350.54 350.84 351.15 710
720 351.46 351.77 352.08 352.38 352.69 353.00 353.30 353.61 353.92 354.22 720
730 354.53 354.84 355.14 355.45 355.76 356.06 356.37 356.67 356.98 357.28 730
740 357.59 357.90 358.20 358.51 358.81 359.12 359.42 359.72 360.03 360.33 740
750 360.64 360.94 361.25 361.55 361.85 362.16 362.46 362.76 363.07 363.37 750
760 363.67 363.98 364.28 364.58 364.89 365.19 365.49 365.79 366.10 366.40 760
770 366.70 367.00 367.30 367.60 367.91 368.21 368.51 368.81 369.11 369.41 770
780 369.71 370.01 370.31 370.61 370.91 371.21 371.51 371.81 372.11 372.41 780
790 372.71 373.01 373.31 373.61 373.91 374.21 374.51 374.81 375.11 375.41 790
800 375.70 376.00 376.30 376.60 376.90 377.19 377.49 377.79 378.09 378.39 800
810 378.68 378.98 379.28 379.57 379.87 380.17 380.46 380.76 381.06 381.35 810
820 381.65 381.95 382.24 382.54 382.83 383.13 383.42 383.72 384.01 384.31 820
830 384.60 384.90 385.19 385.49 385.78 386.08 386.37 386.67 386.96 387.25 830
840 387.55 387.84 388.14 388.43 388.72 389.02 389.31 389.60 389.90 390.19 840
850 390.48 850
– 12 – 60751 © IEC:2008
5 General requirements
5.1 Tolerance classes
5.1.1 Temperature range of validity
The temperature ranges of validity of tolerance classes for resistors given in Table 2 are
based on the working experience with film and wire resistors showing that in these ranges
most resistors can maintain their tolerances and other performance characteristics. The value
of –196 °C was chosen as being close to the boiling point of liquid nitrogen.
5.1.2 Resistors
The tolerance values of resistors are classified in Table 2. These tolerances apply for
resistors of any value of R . Where the specified temperature range of a particular resistor is
smaller than in this table, this shall be stated.
Table 2 – Tolerance classes for resistors
a
For wire wound resistors For film resistors Tolerance value
Tolerance Temperature range of Tolerance Temperature range of °C
class validity class validity
°C °C
–100 to +350 0 to +150
W 0.1 F 0.1 ± ( 0.1 + 0.0017 | t | )
W 0.15 –100 to +450 F 0.15 –30 to +300 ± ( 0.15 + 0.002 | t | )
W 0.3 –196 to +660 F 0.3 –50 to +500 ± ( 0.3 + 0.005 | t | )
W 0.6 –196 to +660 F 0.6 –50 to +600
± ( 0.6 + 0.01 | t | )
a
| t | = modulus of temperature in °C without regard to sign.
5.1.3 Thermometers
The tolerance values of resistance thermometers are classified in Table 3. These tolerances
apply for thermometers of any value of R . Where the specified temperature range of a
particular thermometer is smaller than in this table, this shall be stated.
Table 3 – Tolerance classes for thermometers
Temperature range of validity
a
Tolerance class °C Tolerance values
°C
Wire wound resistors Film resistors
0 to +150
AA –50 to +250 ± ( 0.1 + 0.0017 | t |)
A –100 to +450 –30 to +300 ± ( 0.15 + 0.002 | t | )
B –196 to +600 –50 to +500
± ( 0.3 + 0.005 | t | )
–50 to +600
C –196 to +600 ± ( 0.6 + 0.01 | t | )
a
| t | = modulus of temperature in °C without regard to sign.
5.1.4 Special tolerance classes and special temperature ranges of validity
Tolerances and ranges of validity which differ from values given in Table 2 and Table 3 shall
be agreed between manufacturer and user. Recommended special tolerance classes are
constructed as multiples or fractions of class B tolerance values. A special tolerance class
60751 © IEC:2008 – 13 –
without specification of the temperature range of validity is not permissible. It is left to the
manufacturers and users to establish tolerances for their thermometers or resistors at
temperatures outside the ranges in Table 2 and Table 3.
Special tolerance classes may also be defined for restricted or extended temperature ranges,
e.g. for the ranges –196 °C to 850 °C or −200 °C to 660 °C.
5.2 Measuring current
The measuring current to the resistor shall be limited to a value at which the self-heating of
the thermometer under conditions as specified in 6.4.3 does not exceed 25 % of the tolerance
value of the declared tolerance class. The measuring current is usually not more than 1 mA
for a 100 Ω wire wound resistor.
5.3 Electrical supply
Resistors and thermometers shall be constructed so that they are suitable for use in
measuring systems using direct current or alternating current at frequencies up to 100 Hz.
Some measuring systems may require operation at higher frequencies.
5.4 Connecting wire configuration
All thermometers of tolerance class better than class B shall have 3 wire or 4 wire
configuration.
Thermometers may be constructed with one or two resistors and a variety of internal
connecting wire configurations. Identification and/or designation of the terminals is shown in
Figure 1.
2-wire-configuration 3-wire-configuration 4-wire-configuration
Red
Red
Red
Red
Red
1 resistor
White
White
White
White
Red
Red
Red
Red
Red
White
White
White
White
Yellow
Yellow
2 resistors
Yellow
Yellow
Black
(Grey)
Black
Black
(Grey) Black
(Grey)
(Grey)
Black
(Grey)
IEC 870/08
Figure 1 – Connecting configurations
– 14 – 60751 © IEC:2008
6 Tests
6.1 General
Tests shall be carried out to prove that resistors or thermometers comply with the
requirements of this standard.
It is not intended or recommended that all tests should be carried out on every resistor or
thermometer supplied. Different kinds of tests are therefore described in this clause.
6.1.1 Routine production tests
Routine production tests shall be carried out on every resistor or thermometer manufactured
in accordance with this standard. These tests are also included in the specified type tests.
6.1.2 Type tests
Type tests shall be carried out on samples of each particular design and range of resistor or
thermometer. These are subdivided into tests for all forms of resistors or thermometers.
6.1.3 Additional type tests
Additional type tests may be required by other regulations or be agreed between
manufacturer and user for special applications. If not stated otherwise, there are no fixed
specifications for these test items. The results of the tests shall be made available on request.
6.2 Routine production tests for resistors
6.2.1 Tolerance acceptance test
All types of resistors shall be tested at one temperature at least. The test temperature shall be
in the range from –5 °C to +30 °C, preferably 0 °C.
Resistors of the tolerance classes 0.15 or better shall be tested at one additional temperature
at least. This test temperature shall be the upper or lower temperature limit of the resistor, or
spaced from the first test temperature by a minimum of 90 °C, whichever is less.
The manufacturer shall guarantee that resistances are within the specified tolerance class.
When selecting the resistors, the measurement uncertainty of the test has to be taken into
account. An example is given in Figure 2: if measured by the manufacturer, only resistor No. 1
is within the tolerance class. If measured by the customer, only resistor No. 4 can be rejected.
Therefore, the selection criteria for the manufacturer to use are as follows: the result of the
test, expressed as a temperature deviation, when added to the corresponding expanded
uncertainty, shall be totally included within the tolerance band.
The rejection criteria for the user are as follows: the tolerance value is not met if the result of
the test, expressed as a temperature deviation, when added to the corresponding expanded
uncertainty, is totally outside the tolerance band.
60751 © IEC:2008 – 15 –
0,2
0,15
Upper
0,1
tolerance limit
0,05
–0,05
Lower
–0,1
tolerance limit
–0,15
1 2 3 4
Resistor N°
IEC 871/08
NOTE At each test result the expanded uncertainty (k=2) is indicated. Measurement uncertainty of manufacturer
and user are assumed to be the same.
Figure 2 – Examples of test results for selecting or rejecting resistors.
6.3 Routine production tests for thermometers
6.3.1 Insulation resistance at ambient temperature
The insulation resistance between each terminal and the sheath shall be tested with a test
voltage at minimum 100 V d.c.
The insulation resistance shall be not less than 100 MΩ.
6.3.2 Sheath integrity test
The integrity of the sheath and all closure weldings shall be tested by suitable means, for
example the following tests:
6.3.2.1 Water quench test
The thermometer shall be subjected to a minimum temperature of 300 °C for a minimum time
of 5 min and then immediately plunged into water at room temperature. Then the insulation
resistance shall be measured while the thermometer is immersed. The insulation resistance
shall meet the requirements of 6.5.1.
6.3.2.2 Nitrogen pressure test
The thermometer shall be externally pressurized for approximately 30 s at a minimum
pressure of 2.5 MPa in a nitrogen gas, after which the thermometer shall be immediately
immersed in water or alcohol. There shall be no bubbling from the weld.
6.3.2.3 Liquid nitrogen test
The thermometer shall be immersed in liquid nitrogen until the temperature is stabilized, after
which the thermometer shall be immediately immersed in water or alcohol. There shall be no
bubbling from the weld.
Deviation from reference / °C
– 16 – 60751 © IEC:2008
The integrity of the sheath may also be tested by other suitable means. For particular
applications, sheath integrity tests may be agreed between user and manufacturer.
This test is only recommended for thermometers that can be used at temperatures down to
-196 °C.
6.3.3 Dimensional test
In the case for which the thermometer manufactured is covered by the scope of IEC 61152,
the outside diameter and the straightness shall be tested to be in accordance with the
requirements of the above-mentioned standard.
6.3.4 Tolerance acceptance test
The manufacturer has to assure that resistors of the appropriate tolerance class have been
used. Thermometers of tolerance classes A and better (see 5.1 of this standard) shall be
tested for resistance accuracy at one temperature in the range of –5 °C to +30 °C.
Acceptance and rejection criteria are the same as described in 6.2.1 of this standard.
6.4 Type tests for resistors
6.4.1 Tolerances
The tolerance values for the specified tolerance class shall be met for the whole temperature
range of validity. The number of necessary measurements for this test depends on the
temperature range and the tolerance class and shall include temperatures close to the upper
and lower limits of the declared temperature range.
6.4.2 Stability at upper temperature limit
The resistor shall be subjected to its declared upper temperature limit in air for 1 000 hours.
The drift of the resistance value of the thermometer at 0 °C after the test shall not be more
than the tolerance value of the declared tolerance class.
6.4.3 Self-heating
The self-heating coefficient expressed in °C/mW shall be evaluated at a temperature between
0 °C and 30 °C in flowing air with a velocity of (3 ± 0.3) m/s and/or in flowing water with a
velocity >0.2 m/s. The self-heating under the above mentioned conditions shall not exceed
25 % of the tolerance value of the declared tolerance class at the declared maximum
measuring current.
6.5 Type tests for thermometers
6.5.1 Insulation resistance at elevated temperatures
The insulation resistance shall be tested with the thermometer being at the rated maximum
temperature over at least the minimum immersion depth and a test voltage minimum of 10 V
d.c. The insulation resistance between each terminal and the sheath shall not be less than
indicated in Table 4.
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