Maintenance and cleaning – WIKA TR25 Benutzerhandbuch
Seite 23
WIKA operating instructions model TR25 (Ex i)
14073045.01 10/2013 GB/D
23
GB
As safety clearance for type-examined instruments (for T6 to T3), another 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 forT3 = 200 °C
Safety clearance for type-examined instruments (T6 to T3)
1)
= 5 K
Safety clearance for type-examined instruments (T1 to T2)
1)
= 10 K
1) EN/IEC 60079-0: 2009 Section 26.5.1
Simplified verification of intrinsic safety for the above-mentioned combination
Measuring insert
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 capaci-
tance of the electrical connection leads.
10. Maintenance and cleaning
10.1 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.
10.2 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 12.2 “Return”.
9. Calculation examples ... / 10. Maintenance and cleaning