Emerson Process Management 8732 manual 00809-0100-4663, Rev BA January Sensor Test

Rosemount 8732

Reference Manual

00809-0100-4663, Rev BA January 2010

Table 6-5. Sensor Test

Test	Sensor	Required	Measuring at		Expected Value			Potential Cause		Corrective Action
	Location	Equipment	Connections
A. Sensor	Installed or	Multimeter	1 and 2 = R		2  R  18			• Open or		• Remove and
Coil	Uninstalled								Shorted Coil		replace sensor
B. Shields to	Installed or	Multimeter	17 and		 0.2			•	Moisture in	•	Clean terminal
Case	Uninstalled			and case					terminal block		block
								• Leaky electrode		• Remove sensor
			ground					• Process behind
			17 and case						liner
			ground
C. Coil Shield	Installed or	Multimeter	1 and		 (< 1nS)			•	Process behind	•	Remove sensor
to Coil	Uninstalled		2 and		 (< 1nS)				liner		and dry
								•	Leaky electrode	•	Clean terminal
								•	Moisture in		block
									terminal block	•	Confirm with
											sensor coil test
D. Electrode	Installed	LCR (Set to	18 and 17 = R1		R1 and R2 should be stable			• Unstable R1 or		• Remove coating
Shield to		Resistance	19 and 17 = R2		NO:	R1–R2	 300		R values		from sensor wall
Electrode		and 120 Hz)			N5, E5, CD,				2	•	Use bulletnose
									confirm coated
					ED:	R1 R2	 1500		electrode		electrodes
								•	Shorted	•	Repeat
									electrode		measurement
								•	Electrode not in	•	Pull sensor,
									contact with		complete test in
									process		Table 6-6and
								• Empty Pipe			Table 6-7 on
								•	Low conductivity		page 6-10out of
								•	Leaky electrode		line.

To test the sensor, a multimeter capable of measuring conductance in nanosiemens is preferred. Nanosiemens is the reciprocal of resistance.

1nanosiemens	=	1
		----------------------------
		1gigaohm
	or
1nanosiemens	=	1
		------------------------------
		1  109ohm

6-8