Emerson Micro Motion 3711 Configuration And Use Manual page 193

Maintenance and Troubleshooting
There should be no open circuits, i.e., no infinite resistance readings. The LPO and RPO
readings should be the same or very close (± 5 ohms). If there are any unusual readings, repeat
the pin resistance tests at the sensor junction box to eliminate the possibility of faulty cable.
The readings for each pin pair should match at both ends.
5. Leave the core processor terminal blocks disconnected. At the sensor, remove the lid of the
junction box and test each sensor terminal for a short to case by placing one DMM lead on the
terminal and the other lead on the sensor case.
With the DMM set to its highest range, there should be infinite resistance on each lead. If there
is any resistance at all, there is a short to case. See Table 15-9 for possible causes and
solutions.
6. Test pin pairs as follows:
a. Brown against all other terminals except Red
b. Red against all other terminals except Brown
c. Green against all other terminals except White
d. White against all other terminals except Green
e. Blue against all other terminals except Gray
f. Gray against all other terminals except Blue
g. Orange against all other terminals except Yellow and Violet
h. Yellow against all other terminals except Orange and Violet
i. Violet against all other terminals except Yellow and Orange
Note: D600 sensors and CMF400 sensors with booster amplifiers have different terminal pairs.
Contact Micro Motion for assistance (see Section 1.8).
There should be infinite resistance for each pair. If there is any resistance at all, there is a short
between terminals. See Table 15-9 for possible causes and solutions.
7. If the problem is not resolved, contact Micro Motion (see Section 1.8).
8. To return to normal operation:
a. Plug the terminal blocks into the terminal board.
b. Replace the end-cap on the core processor housing.
c. Replace the lid on the sensor junction box.
Note: When reassembling the meter components, be sure to grease all O-rings.
Table 15-9 Sensor and cable short to case possible causes and remedies
Possible cause
Moisture inside the sensor junction box
Liquid or moisture inside the sensor case
Internally shorted feedthrough (sealed passage
for wiring from sensor to sensor junction box)
Faulty cable
Improper wire termination
Configuration and Use Manual
Solution
Make sure that the junction box is dry and no corrosion is present.
Contact Micro Motion. See Section 1.8.
Contact Micro Motion. See Section 1.8.
Replace cable.
Verify wire terminations inside sensor junction box. See Micro
Motion's 9-Wire Cable Preparation and Installation Guide or the
sensor documentation.
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