Technical information

Operating limits and tolerances of platinum resistancethermometers per DIN EN IEC 60751
WIKA data sheet IN 00.17

General information
Temperature is a measurement for the thermal state of amaterial - so a measurement of the average kinetic energyof its molecules. A close thermal contact between twobodies is needed in order that these bodies adopt the same
temperature (temperature equalisation). The body to bemeasured should be coupled as closely as possible to thetemperature sensor system.

Resistance basic values at 0 °C
Designation
Pt100

Pt1000

Basic value in Ω100

1,000

Bold: Standard version

The most established temperature measurement methods
are based on material or body properties that change
depending on the temperature. One of the most-usedmethods is the measurement with a resistance thermometer.
This document outlines the recurrent concepts andtechnologies that apply to all resistance thermometers
produced by WIKA.
Standard version
If there are no additional specifications or customer
requirements, we will recommend this selection, or wewill select this option when offering or producing thethermometer.

Sensor technology
The electrical resistance of a resistance thermometer'ssensor changes with the temperature. As the resistanceincreases when temperature is raised, we refer to it as PTC(Positive Temperature Coefficient).
Pt100 or Pt1000 measuring resistors are normally used forindustrial applications. The exact characteristics of thesemeasuring resistors, and the thermometers based on them,
are defined in IEC 60751. The most important characteristics
are described in this document.

WIKA data sheet IN 00.17 ∙ 11/2020

Fig. left: Thin-film measuring resistor
Fig. centre: Glass measuring resistor
Fig. right: Ceramic measuring resistor

Page 1 of 8

Measuring resistor designs
Those measuring resistors used in thermometers can be wire-wound measuring resistors (W = Wire-Wound) or
thin-film resistors (F = Thin-Film).

Thin-film measuring resistors (F), standard version
For thin-film measuring resistors, a very thin platinum film isapplied to a ceramic carrier plate. Then, connecting wires areattached. Finally, the platinum film and the connecting wire
connection are sealed against external effects by a layer ofglass.

Thin-film measuring resistor

The thin-film measuring resistor is characterised by■ Temperature range: -50 ... +500 °C 1)■ High vibration resistance■ Very small size

■ Good price/performance ratio

Thin-film measuring resistors are the standard design unlessthe temperature range or an explicit customer request
exclude them.

Wire-wound measuring resistors (W)In this design, a very thin platinum wire is encased within around protective body. This design has been well-established
for decades and is accepted worldwide.
Two subtypes are available that differ in the choice of
insulating material.
■ Glass measuring resistor

The bifilar wire of the glass measuring resistor is fused
within a glass body.
The glass measuring resistor is characterised by:■ Temperature range: -196 ... +400 °C 1)■ High vibration resistance

Glass measuring resistor■ Ceramic measuring resistor

The platinum wire of a ceramic measuring resistor isspiral-wound and located in a cylindrical cavity in theprotective body.
The ceramic measuring resistor is characterised by:■ Temperature range: -196 ... +600 °C 1)■ Limited vibration resistance

Ceramic measuring resistor

1) The specifications apply to class B, see also table on page 4

WIKA data sheet IN 00.17 ∙ 11/2020

Page 2 of 8

Sensor connection methods■ 2-wire connection

The lead resistance to the sensor is recorded as an error
in the measurement. For this reason, this connection type
is not advisable when using Pt100 measuring resistors fortolerance classes A and AA, since the electrical resistanceof the connecting cables and their own temperaturedependency are fully included in the measuring result andthus falsify it.

redwhiteApplications■ Connecting cables up to 250 mm■ Standard when using Pt1000 measuring resistors■ 3-wire connection (standard version)

The influence of the lead resistance is compensated as
far as possible. The maximum length of the connecting
cable depends on the conductor cross-section andthe compensation options of the evaluation electronics(transmitter, display, controller or process control system).

red
redwhiteApplications■ Connecting cables up to approx. 30 m

■ 4-wire connection

The influence of the connecting cable on the measuring
result is completely eliminated since any possible
asymmetries in the connecting cable's lead resistance arealso compensated.
The maximum length of the connecting cable depends
on the conductor cross-section and the compensation
options of the evaluation electronics (transmitter, display,controller or process control system). A 4-wire connection
can also be used as a 2-wire or 3-wire connection bydisconnecting the unnecessary conductors.

red
red
white
white

Applications■ Laboratory technology■ Calibration technology■ Tolerance class A or AA■ Connecting cables up to 1,000 m

Dual sensors
In the standard version a single sensor is fitted.
The combination of black and yellow is reserved for anoptional second measuring resistor. For certain combinations(e.g. small diameter) dual sensors are not possible fortechnical reasons.
WIKA data sheet IN 00.17 ∙ 11/2020

Page 3 of 8

Relationship between temperature and resistanceFor each temperature there is exactly one resistance value.
This clear relationship can be described by mathematicalformulae.
For the temperature range -200 ... 0 °C the following applies,
irrespective of the resistor design:

Rt = R0 [1 + At + Bt² + C (t - 100 °C) • t³ ]For the temperature range 0 ... 600 °C the following applies:

Rt = R0 [1 + At + Bt² ]Legend:t= Temperature in °C
Rt = Resistance in ohms at the measured temperature
R0 = Resistance in ohms at t = 0 °C (e.g. 100 ohms)

For the calculation, the following constants apply

A = 3.9083 • 10-3 (°C-1)
B = -5.7750 • 10-7 (°C-2)
C = -4.1830 • 10-12 (°C-4)

Operating limits and tolerance classes
Both measuring resistor versions (wire-wound/thin-film) differ
in the possible tolerances at the operating temperatures.
ClassBAAATemperature range in °C

Wire-wound (W)Thin-film (F)Tolerance value-196 … +600

-50 … +500±(0.30 + 0.0050 | t |) 1)-50 … +250

0 … 150±(0.10 + 0.0017 | t |) 1)-100 … +450

-30 … +300±(0.15 + 0.0020 | t |) 1)

1) | t | is the numerical value of the temperature in °C irrespective of the sign.
Bold: Standard version

Under certain conditions, thermometers/measuring insertswith built-in measuring resistors can be operated in atemperature range outside the temperature range of thespecified class.
The following must be observed regarding the compliancewith the tolerance class:With standard instruments, the class A specified before canno longer be confirmed if the thermometer or measuring
insert was operated above or below the class A temperature
range. The dwell time is not relevant here.
Even if the temperature is in the range of class A again, thetolerance class of the measuring resistor is no longer defined.

WIKA data sheet IN 00.17 ∙ 11/2020

Page 4 of 8

Resistance values and tolerance values with selected temperatures (Pt100)

Max. permissible deviation in °C (irrespective of the sign)

Tolerance value IEC 60751 for resistance thermometers with film measuring resistors

Class BClass AClass AA

Temperature in °C

Max. permissible deviation in °C (irrespective of the sign)

Tolerance value IEC 60751 for resistance thermometers with wire-wound measuring resistors

Class BClass AClass AA

Temperature in °C

WIKA data sheet IN 00.17 ∙ 11/2020

Page 5 of 8

Temperature values and tolerance values with selected resistance values (Pt100)
Resistance value in Ω

Temperature value in °C (ITS 90)

50-126.07 ... -124.22

Tolerance class BTolerance class A

Tolerance class AA-51.02 ...

-50.52-50.96 ... -50.58-125.55 ... -124.75-125.46 ... -124.83

80-51.32 ... -50.22-0.30 ...

+0.30

-0.15 ...

+0.15

-0.10 ...

+0.10

110

25.26 ...

26.11

25.48 ...

25.89

25.54 ...

25.83

100
150

129.50 ... 131.40

130.04 ... 130.86

130.13 ... 130.77

264.72 ... 267.98

265.67 ... 267.03

265.80 ... 266.90

300

554.60 ... 560.78

556.42 ... 558.95

556.64 ... 558.74

200This table can be used to check the evaluation electronics,e.g. by means of a decade resistor:
This means if the sensor or the measuring resistor issimulated by a decade resistor, the evaluation electronics
must display a temperature value within the limit values
specified above.

Resistance values and tolerance values with selected temperatures (Pt100)
Temperature in °C(ITS 90)

Resistance value in Ω
Tolerance class B

Tolerance class A

19.69 ...

20.80

-100

59.93 ...

60.58

60.11 ...

60.40

-50

80.09 ...

80.52

80.21 ...

80.41

80.23 ...

80.38

-30

88.04 ...

88.40

88.14 ...

88.30

88.16 ...

88.28

0

99.88 ... 100.12

99.94 ... 100.06

99.96 ... 100.04

20150-196-Tolerance class AA-

107.64 ... 107.95

107.72 ... 107.87

107.74 ... 107.85

100

138.20 ... 138.81

138.37 ... 138.64

138.40 ... 138.61

156.93 ... 157.72

157.16 ... 157.49

157.91 ... 157.64

250

193.54 ... 194.66

193.86 ... 194.33

193.91 ... 194.29

211.41 ... 212.69

211.78 ... 212.32-

450

263.31 ... 265.04

263.82 ... 264.53

-

300

500
600

280.04 ... 281.91--

312.65 ... 314.77--

This table represents the calibration process with predefinedtemperatures.
This means if a temperature standard is available, theresistance value of the test item must lie within the limits
specified above.

WIKA data sheet IN 00.17 ∙ 11/2020

Page 6 of 8Vibration resistance of resistance thermometers
In accordance with IEC 60751, the design of a resistancethermometer can be influenced by vibration-induced
accelerations that can be up to 3 g (30 m/s²) and occur in afrequency range from 10 … 500 Hz.

The vibration resistance data listed in the data sheets of theelectrical thermometers from WIKA refer to the “peak-topeak” value.

15

Acceleration [g]105Amplitudevalue

Peak-to-peakvalue

0Time-5-10-15VersionRequired vibration resistanceper IEC 60751 in g 1)
(peak-to-peak)

Determined vibration resistance
WIKA per IEC 60751 in g 1)
(peak-to-peak)

Vibration resistant(optional, thin-film measuring resistor)-

20

Highly vibration resistant(special construction, thin-film measuring resistor)-50

3Standard61) 9.81 m/s²

Measuring resistor

Vibration resistance (peak-to-peak)Ø 3 mm (MI cable)
6g

20 g

50 g

2 x Pt100 / 2 x Pt1000xx

1 x Pt100 / 1 x Pt1000x-

1 x Pt100 / 1 x Pt1000x

2 x Pt100 / 2 x Pt1000x

Thin-film (F)1 x Pt100 / 1 x Pt1000

Thin-film, face-sensitive (FS)Wire-wound (W)xØ 6 mm (MI cable)
6g

20 g

50 g

-x

x

x

-x

----x

----x

--x

x

x

x

x

The vibration resistance data listed in the data sheets of the electrical thermometers from WIKA only refer to the sensor tip.

WIKA data sheet IN 00.17 ∙ 11/2020

Page 7 of 8

11/2020 EN© 01/2010 WIKA Alexander Wiegand SE & Co. KG, alle Rechte vorbehalten.
The specifications given in this document represent the state of engineering at the time of publishing.
We reserve the right to make modifications to the specifications and materials.

WIKA data sheet IN 00.17 ∙ 11/2020

Page 8 of 8

WIKA Alexander Wiegand SE & Co. KG
Alexander-Wiegand-Straße 30
63911 Klingenberg/GermanyTel.
+49 9372 132-0
Fax+49 9372 132-406
info@wika.de
www.wika.de