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Configuration and Use Manual 137
Troubleshooting
Measurement Performance DefaultsTroubleshootingCompensation
11.20.3 Drive gain problems
Problems with drive gain can appear in several different forms:
• Saturated or excessive (near 100%) drive gain
• Erratic drive gain (e.g., rapid shifting from positive to negative)
• Negative drive gain
See Table 11-5 for a list of possible problems and remedies.
11.20.4 Low pickoff voltage
Low pickoff voltage can be caused by several problems. See Table 11-6.
Table 11-4 Sensor pickoff values
Sensor
(1)
(1) If your sensor is not listed, contact Micro Motion.
Pickoff value
ELITE
®
CMF sensors 3.4 mV peak-to-peak per Hz based on sensor flow tube frequency
F025, F050, F100 sensors 3.4 mV peak-to-peak per Hz based on sensor flow tube frequency
F200 sensors 2.0 mV peak-to-peak per Hz based on sensor flow tube frequency
H025, H050, H100 sensors 3.4 mV peak-to-peak per Hz based on sensor flow tube frequency
H200 sensors 2.0 mV peak-to-peak per Hz based on sensor flow tube frequency
R025, R050, or R100 sensors 3.4 mV peak-to-peak per Hz based on sensor flow tube frequency
R200 sensors 2.0 mV peak-to-peak per Hz based on sensor flow tube frequency
T-Series sensors 0.5 mV peak-to-peak per Hz based on sensor flow tube frequency
CMF400 I.S. sensors 2.7 mV peak-to-peak per Hz based on sensor flow tube frequency
Table 11-5 Drive gain problems, causes, and remedies
Cause Possible remedy
Excessive slug flow • See Section 11.14.
Cavitation or flashing • Increase inlet or back pressure at the sensor.
• If a pump is located upstream from the sensor, increase the distance
between the pump and sensor.
Plugged flow tube • Purge the flow tubes.
Mechanical binding of sensor tubes • Ensure sensor tubes are free to vibrate. Possible problems include:
- Pipe stress. Check for pipe stress and eliminate if present.
- Lateral tube shift due to hammer effect. If this is a possibility,
contact Micro Motion.
- Warped tubes caused by overpressurization. If this is a possibility,
contact Micro Motion.
Incorrect sensor type configured • Verify sensor type configuration, then verify sensor characterization.
See Section 6.2.
Open drive or left pickoff sensor coil • Contact Micro Motion.
Drive board or module failure, cracked flow tube,
or sensor imbalance
• Contact Micro Motion.