Emerson Rosemount 8732 manual Perform the auto zero function with full pipe and no flow

Rosemount 8732

Reference Manual

00809-0100-4665, Rev AA August 2010

Table 6-4. Advanced Troubleshooting–Rosemount 8732

Symptom	Potential Cause		Corrective Action
Meter output is unstable	Medium to low conductivity fluids (10–	Eliminate cable vibration:
	25 microsiemens/cm) combined with	•	Integral mount
	cable vibration or 60 Hz interference	•	Move cable to lower vibration run
		•	Tie down cable mechanically
		•	Trim electrode and coil wires
		• See “Conduit Cables” on page 2-6
		•	Route cable line away from other equipment
			powered by 60 Hz
		•	Use 8712-0752-1,3 cable
	Electrode incompatibility	Check the Technical Data Sheet, Magnetic Flowmeter Material
		Selection Guide (document number 00816-0100-3033), for
		chemical compatibility with electrode material.
	Improper grounding	Check ground wiring – see “Mount the Transmitter” on page 2-3
		for wiring and grounding procedures
	High local magnetic or electric fields	Move magnetic flowmeter (20–25 ft away is usually acceptable)
	Control loop improperly tuned	Check control loop tuning
	Sticky valve (look for periodic	Service valve
	oscillation of meter output)
	Sensor failure	Perform the sensor Tests A, B, C, and D
		(See Table 6-5 on page 6-8)
Reading does not appear to be	Transmitter, control system, or other	Check all configuration variables for the transmitter, sensor,
within rated accuracy	receiving device not configured	communicator, and/or control system
	properly	Check these other transmitter settings:
		Sensor calibration number
		Units
		Line size
	Electrode coating	Use bulletnose electrodes in the Rosemount 8705 Sensor.
		Downsize the sensor to increase the flow rate above 3 ft/s.
		Periodically clean the sensor
	Air in line	Move the sensor to another location in the process line to
		ensure that it is full under all conditions
	Flow rate is below 1 ft/s	See the accuracy specification for specific transmitter and
	(specification issue)	sensor
	Insufficient upstream/downstream	Move sensor to location where 5 pipe diameters upstream and 2
	pipe diameter	pipe diameters downstream is possible
	Cables for multiple magmeters run	Run only one conduit cable between each sensor and
	through same conduit	transmitter
	Auto zero was not performed when the	Perform the auto zero function with full pipe and no flow
	coil drive frequency was changed from
	5 Hz to 37.5 Hz
	Sensor failure—shorted electrode	See Table 6-5 on page 6-8
	Sensor failure—shorted or open coil	See Table 6-5 on page 6-8
	Transmitter failure	Replace the electronics board
	Transmitter wired to correct sensor	Check wiring

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