Emerson Process Management MICRO MOTION 2400S - Manual (Page 132)

124 Micro Motion ® Model 2400S Transmitters for DeviceNet ™
Troubleshooting
11.19.3 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 11-6 for a list of possible problems and remedies.
11.19.4 Low pickoff voltage
Low pickoff voltage can be caused by several problems. See Table 11-7.
Table 11-6 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. See Section 11.3.
- 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. See Section 11.3.
Drive board or module failure, cracked flow tube,
or sensor imbalance • Contact Micro Motion. See Section 11.3.
Table 11-7 Low pickoff voltage causes and remedies
Cause Possible remedy
Slug flow • See Section 11.14.
No tube vibration in sensor • Check for plugging.
Moisture in the sensor electronics • Eliminate the moisture in the sensor electronics.
Damaged sensor • Ensure sensor is free to vibrate (no mechanical binding). 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. See Section 11.3.
- Warped tubes caused by overpressurization. If this is a possibility,
contact Micro Motion.
• Test sensor circuitry. See Section 11.20.
• Contact Micro Motion.