IEC 60539-1:2016/COR1:2017

 IEC 2017
INTERNATIONAL ELECTROTECHNICAL COMMISSION

COMMISSION ÉLECTROTECHNIQUE INTERNATIONALE

____________
IEC 60539-1 IEC 60539-1
Edition 3.0  2016-04 Édition 3.0  2016-04

DIRECTLY HEATED NEGATIVE TEMPERATURE THERMISTANCES À COEFFICIENT DE
COEFFICIENT THERMISTORS – TEMPÉRATURE
NÉGATIF À CHAUFFAGE DIRECT –
Part 1: Generic specification
Partie 1: Spécification générique

CO RRI G E NDUM 1
Corrections to the French version appear after the English text.
Les corrections à la version française sont données après le texte anglais.

5.12 Thermal time constant by ambient temperature change (τ )
a
Replace with this new subclause 5.12:
5.12 Thermal time constant by ambient temperature change (τ )
a
5.12.1 The hot to cold thermal time constant for ambient temperature change
5.12.1.1 General
The method of test shall be as described below.
5.12.1.2 Initial measurements
The zero-power resistance shall be measured as prescribed in 5.6 at the temperature T
i
followed by the same measurement at T . The temperature T is calculated as follows:
a i
T T – (T – T ) × 0,632
=
i b b a
where
T is (273,15 + 85) K, unless otherwise specified in the detail specification;

b
T is (273,15 + 25) K, unless otherwise specified in the detail specification.
a
Measurements shall be recorded.
5.12.1.3 Preconditioning
The thermistor shall be immersed in a medium with a temperature T and allowed to reach the
b
medium temperature.
IEC 60539-1:2016-04/COR1:2017-09(en-fr)

– 2 – IEC 60539-1:2016/COR1:2017

 IEC 2017
5.12.1.4 Test methods
The thermistor shall be transferred rapidly to a medium with a temperature T . The time it
a
takes for the thermistor to reach the zero-power resistance at T shall be measured.
i
The resulting time is the thermal time constant by ambient temperature change.

5.12.2 The cold to hot thermal time constant for ambient temperature change

5.12.2.1 General
The method of test shall be as described below.

5.12.2.2 Initial measurements
The zero-power resistance shall be measured as prescribed in 5.6 at the temperature T
i
followed by the same measurement at T . The temperature T is calculated as follows:
a i
T T + (T – T ) × 0,632
=
i a b a
where
T is (273,15 + 85) K, unless otherwise specified in the detail specification;
b
T is (273,15 + 25) K, unless otherwise specified in the detail specification.
a
Measurements shall be recorded.
5.12.2.3 Preconditioning
The thermistor shall be immersed in a medium with a temperature T and allowed to reach the
a
medium temperature.
5.12.2.4 Test methods
The thermistor shall be transferred rapidly to a medium with a temperature T . The time it
b
takes for the thermistor to reach the zero-power resistance at T shall be measured.
i
The resulting time is the thermal time constant by ambient temperature change.
5.12.3 Final measurements and requirements
The thermal time constant by ambient temperature change shall be within the limits specified
in the detail specification.
5.12.4 Requirements
The medium used in 5.12.1.2, 5.12.1.3, 5.12.2.2 and 5.12.2.3, the temperature tolerance on
T and T , air (flow rate) or liquid (flow rate and viscosity) shall be defined in the detail
a b
specification.
NOTE This method is not suitable for miniature thermistors because the change of temperature during transfer
from the first to the second medium can lead to a considerable measur
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