WIKA TC12-M - Handbuch (Seite 29)

GB
8. Safety-related instructions for the different variants
14083458.01 09/2013 GB/D
WIKA operating instructions models TR12, TC12 (Ex i) 29
The thermometer should be operated with a power-limiting circuit.
P
max:
2 W
U
max:
30 V
Powering with Ex ia electrical circuit fulfills these conditions. The responsibility rests with the
operator.
Temperature class classification, ambient temperatures
A heating in the connection head can occur with variant 2 through faulty electronics. The
permissible ambient temperatures depend on the housing used and any additionally fitted
head-mounted transmitter.
For all WIKA connection heads with built-in WIKA temperature transmitters, the
following interrelation is valid:
The temperature increase on the surface of the connection head or housing is less than
25 K if the following conditions are observed: power supply U
B
maximum DC 30 V when the
transmitter is operated in a current limit of 22.5 mA.
This yields the following temperature class classification.
Temperature class
Ambient temperature
T6 (-50) 1) -40 … +55 °C
T5 (-50) 1) -40 … +75 °C
T4, T3, T2, T1 (-50) 1) -40 … +85 °C
The temperature class is dependent upon the user application and the ambient
temperature.
1) The value in brackets applies only for specific low-temperature designs.
U
i
= depending on the built-in transmitter/digital display
I
i
= depending on the built-in transmitter/digital display
P
i
= depending on the built-in transmitter/digital display
L
i
= depending on the built-in transmitter/digital display
C
i
= depending on the built-in transmitter/digital display
The permissible ambient temperatures for third-party products can be seen from the
relevant approvals and/or data sheets. However, an impermissible heat reflux from the
process which can exceed the operating temperature of the transmitter or the housing, must
be prevented through suitable heat insulation or a suitably long neck tube.