EN
14073045.04 03/2019 EN/DE
WIKA operating instructions model TR25 (Ex i)
27
Simplified verification of intrinsic safety for the above-mentioned combination
Sensor
Head transmitter
Power supply
U
i
: DC 30 V
U
o
: DC 6.5 V
U
i
: DC 30 V
U
o
: DC 25.4 V
I
i
: 550 mA
I
o
: 9.3 mA
I
i
: 130 mA
I
o
: 88.2 mA
P
i
(max) at the sensor: 1.5 W
P
o
: 15.2 mW
P
i
: 800 mW
P
o
: 560 mW
C
i
: negligible
C
o
: 24 µF
C
i
: 7.8 nF
C
o
: 93 nF
L
i
: negligible
L
o
: 365 mH
L
i
: 100 µH
L
o
: 2.7 mH
Upon comparing the values, it is obvious that it is permissible to connect these units to one
another. However, the operator must also take into account the values for inductance and
capacitance of the electrical connection leads.
11. Maintenance and cleaning
11.1 Maintenance
The resistance thermometer described here is maintenance-free.
Repairs should only be carried out by the manufacturer or, following prior consultation, by
correspondingly qualified skilled personnel.
11.2 Cleaning
CAUTION!
■
Before cleaning, correctly disconnect the instrument from the pressure
supply, switch it off and disconnect it from the mains.
■
Clean the instrument with a moist cloth.
■
Electrical connections must not come into contact with moisture.
■
Wash or clean the dismounted instrument before returning it, in order to
protect persons and the environment from exposure to residual media.
■
Residual media in the dismounted instrument can result in a risk to persons,
the environment and equipment. Take sufficient precautionary measures.
For information on returning the instrument see chapter 13.2 “Return”.
11.3 Calibration, Recalibration
It is recommended that the measuring instrument is recalibrated at regular intervals of
approx. 24 months. This period can reduce, depending on the particular application. The
measuring instrument must be dismounted for calibration. The calibration can only be
carried out by the manufacturer.
10. Calculation examples ... / 11. Maintenance and cleaning
