Endress+Hauser Mycom S CLM 153 Operating Instructions Manual page 86

7 Maintenance
86
7.1.5 Checking conductive conductivity sensors
• Measuring surface connection:
The measuring surfaces are directly connected with connections of the sensor plug.
Check with ohmmeter at < 1 Ω .
• Measuring surface shunt:
A shunt may not exist between the measuring surfaces. Check with ohmmeter at
> 20 M Ω .
• Temperature sensor shunt:
A shunt may not exist between the measuring surfaces and the temperature sensor.
Check with ohmmeter at > 20 M Ω .
• Temperature sensor
Refer to the sensor nameplate for the type of temperature sensor used.
The sensor can be checked with an ohmmeter at the sensor plug:
– Pt 100 at 25 °C = 109.79 Ω
– Pt 1000 at 25 °C = 1097.9 Ω
– NTC 10k at 25 °C = 10 k Ω
• Connection:
Make sure the terminals are correctly assigned for sensors with terminal connection
(CLS 12/13). Check that the terminal screws are secure.
7.1.6 Checking inductive conductivity sensors
The following data apply to sensors CLS 50 and CLS 52.
• Test send coil and receive coil (white and rot coaxial cable, each measured between
inner connector and screen):
– ohmic resistance approx. .5 ... 2 Ω
– Inductance approx. 260 ... 450 mH (at 2 kHz).
• Test coil shunt:
A shunt may not exist between the coils (from red coax to white coax). Check with
ohmmeter at > 20 M Ω .
• Test temperature sensor:
You can use the table in chap. 7.1.3 to check the Pt 100. The resistance values
between the green and white cores and green and yellow cores must be identical.
• Test temperature sensor shunt:
Shunts may not exist between the temperature sensor (green, white or yellow lines)
and the coils (red coax or white coax). Check with ohmmeter at > 20 M Ω .
7.1.7 Checking line extension and boxes
• Use the methods described in Chap. 8.7.2 or 8.7.3. to carry out a quick functional
check from the sensor plug (for conductive sensors) or from the sensor (for inductive
sensors) to the device. The easiest way to connect the resistance decades is with the
"conductivity test adapter" service kit, Order No: 51500629.
• Check the junction boxes for:
– moisture (impact at low conductivity, if necessary dry box, replace seals, insert
dehydrating bag)
– correct connection of all lines
– connection of the outer screening
– security of the terminal screws.
Mycom S CLM 153
Endress+Hauser