Emerson Process Management 2400S manual 6Drive gain problems, causes, and remedies

Troubleshooting

11.19.3Drive 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 11-6for a list of possible problems and remedies.

Table 11-6Drive 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,	• Contact Micro Motion. See Section 11.3.
or sensor imbalance

11.19.4Low pickoff voltage

Low pickoff voltage can be caused by several problems. See Table 11-7.

Table 11-7Low 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.

124 Micro Motion® Model 2400S Transmitters for DeviceNet™