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Possible causes and recommended actions for excessive (saturated)
drive gain (continued)
Table 10-8:
Possible cause Recommended actions
Bent flow tube Check the pickoff voltages (see Section 10.27). If either of them
are close to zero (but neither is zero), the flow tubes may be bent.
The sensor will need to be replaced.
Cracked flow tube Replace the sensor.
Sensor imbalance Contact Micro Motion.
Mechanical binding at sensor Ensure sensor is free to vibrate.
Open drive or left pickoff sen-
sor coil
Contact Micro Motion.
Flow rate out of range Ensure that flow rate is within sensor limits.
Incorrect sensor characteriza-
tion
Verify the characterization parameters.
Erratic drive gain
Possible causes and recommended actions for erratic drive gainTable 10-9:
Possible cause Recommended actions
Wrong K1 characterization constant for sensor Verify the K1 characterization parameter.
Polarity of pick-off reversed or polarity of drive reversed Contact Micro Motion.
Slug flow Check for slug flow. See Section 10.25.
Foreign material caught in flow tubes • Purge the flow tubes.
• Replace the sensor.
10.26.1 Collect drive gain data
Drive gain data can be used to diagnose a variety of process and equipment conditions.
Collect drive gain data from a period of normal operation, and use this data as a baseline
for troubleshooting.
Procedure
1. Navigate to the drive gain data.
2. Observe and record drive gain data over an appropriate period of time, under a
variety of process conditions.
10.27 Check the pickoff voltage
If the pickoff voltage readings are unusually low, you may have any of a variety of process
or equipment problems.
Troubleshooting
208 Micro Motion
®
Model 1700 Transmitters with Analog Outputs