WIKA TR12 Serie Manual De Instrucciones página 12

3. Commissioning, operation
This results in the following fuse rating:
I = sqrt (P / R
s max
I = sqrt (0.8 W / 265 Ω) / 1.7
s
I = 32.32 mA
s
EN
This results in a rated current for a fuse link = 32 mA
Notes for fuse calculation:
The next smallest fuse value, in accordance with IEC 60127, must always be chosen. The
breaking capacity must be matched, by sensible engineering, to the voltage supply. Usual
values for such fuse links lie between AC 20 A and AC 80 A rated breaking capacity.
For a maximum power at the sensor of 0.5 W the following value is given:
I = sqrt (0.5 W / 265 Ω) / 1.7
s
I = 25.55 mA
s
This results in a rated current for a fuse link = 25 mA
When using multiple sensors and simultaneous operation, the sum of the individual powers
must not exceed the value of the maximum permissible power.
Internal resistance of Ø 6 mm TC measuring inserts: approx. 1.2 Ω/m
Internal resistance of Ø 3 mm TC measuring inserts: approx. 5.6 Ω/m
These measured values are valid for room temperature.
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 case is less than 25 K
if the following conditions are observed: Power supply U
transmitter is operated in a current limitation of 22.5 mA.
A heating in the connection head can occur with variant 2 through faulty electronics. The
permissible ambient temperatures depend on the case used and any additionally fitted
head-mounted transmitter.
However, an impermissible heat reflux from the process which can exceed the operating
temperature of the case or the temperature class, must be prevented through suitable heat
insulation or a suitably long neck tube.
12
) / 1.7
w
WIKA additional information TR12/TC12, flameproof enclosure (Ex d)
maximum DC 30 V when the
B