WIKA TR21 Serie Informations Complémentaires page 15

5. Calculation examples for self-heating ... / 6. Accessories
5. Calculation examples for self-heating at the thermowell tip
5.1 Example calculation
Use at the partition to zone 0
The maximum possible temperature, T
being sought.
T is obtained by adding the temperature of the medium and the self-heating. The
max
self-heating depends on the supplied power P
15 K.
Example
Diameter: 6 mm
Medium temperature: T
Temperature class T3 (200 °C) must not be exceeded
Self-heating: 15 K
T = T + self-heating: 150 °C + 15 °C = 165 °C
max M
As safety margin for type-examined instruments (for T6 to T3), an additional 5 °C must be
subtracted from the 200 °C; hence 195 °C would be permissible. This means that in this
case temperature class T3 is not exceeded.
Additional information:
Temperature class for T3 = 200 °C
Safety margin for type-tested instruments (T6 to T3)
Safety margin for type-tested instruments (T2 to T1)
1) EN/IEC 60079-0: 2012 section 26.5.1
6. Accessories
Accessories
Connection cable with moulded connector M12 x 1
Cable box straight, 4-pin, ingress protection IP67
■
Temperature range -20 ... +80 °C
Angled socket, 4-pin, ingress protection IP67
■
Temperature range -20 ... +80 °C
WIKA additional information model TR21 (Ex i)
, at the Ø 6 mm thermowell tip with transmitter is
max
= 150 °C
M
as well as the thermal resistance R
o
= 5 K
1)
= 10 K
1)
2 m
5 m
2 m
5 m
and is
th
Order number
14086880
14086883
14086889
14086891
15
EN