Check The Sensor Coils - Emerson Micro Motion 5700 Configuration And Use Manual

Troubleshooting
March 2019
Tip
You can reduce the occurrence of two-phase flow alerts by setting Two-Phase Flow Low Limit to a
lower value, Two-Phase Flow High Limit to a higher value, or Two-Phase Flow Timeout to a higher
value.

17.32 Check the sensor coils

Checking the sensor coils can identify a cause for a no sensor response alert.
Procedure
1. Disconnect power to the transmitter.
CAUTION
If the transmitter is in a hazardous area, wait 5 minutes before continuing.
2. Unplug the terminal blocks from the terminal board on the core processor.
3. Using a digital multimeter (DMM), check the pickoff coils by placing the DMM leads on the unplugged
terminal blocks for each terminal pair. See
Table 17-6: Coils and test terminal pairs
Coil
Drive coil
Left pickoff coil (LPO)
Right pickoff coil (RPO)
Resistance temperature detector
(RTD)
Lead length compensator (LLC)
Composite RTD
Fixed resistor (see note)
Note
The CMF400 fixed resistor applies only to certain specific CMF400 releases. Contact customer support
for more information.
There should be no open circuits, that is, no infinite resistance readings. The left pickoff and right
pickoff readings should be the same or very close (±5 Ω). If there are any unusual readings, repeat the
coil resistance tests at the sensor junction box to eliminate the possibility of faulty cable. The readings
for each coil pair should match at both ends.
4. Test the terminals in the sensor junction box for shorts to case.
a) Leave the terminal blocks disconnected.
b) Remove the lid of the junction box.
244
Table 17-6 for a list of the coils. Record the values.
Sensor model
All
All
All
All
All except T-Series and CMF400 (see
note)
CMFS025-150 and T-Series
CMFS007, CMFS010, CMFS015,
CMF400, and F300
Micro Motion Model 5700 with Ethernet Transmitters
Configuration and Use Manual
MMI-20029769
Terminal colors
Brown to red
Green to white
Blue to gray
Yellow to violet
Yellow to orange
Yellow to orange
Yellow to orange