Emerson Process Management 53eA Troubleshooting not Related to Measurement Problems

MODEL 54eA			SECTION 16.0
			TROUBLESHOOTING
16.10 TROUBLESHOOTING NOT RELATED TO MEASUREMENT PROBLEMS
	Problem	Action
	Display segments missing	Replace display board
	Alarm relays are chattering	1.	Check alarm setpoints.
		2. Increase hysteresis time delay settings (see Section 5.7)
	Incorrect current output	1.	Verify that output load is less than 600 Ω.
		2.	For minor errors, trim outputs (see Section 13.0)
		3.	Replace power supply board
	Display too light or too dark	Change contrast (see Section 5.5)
	“Level 1, 2 or 3 security: Lock” shown in display	Controller has password protection (see Section 5.13)
	“Hold mode activated” showing in display	Controller is in hold (see Section 5.6, steps 10 and 11)
	“Simulating output 1 or 2” showing in display	Controller is simulating outputs (see Section 5.4)
	“Simulating alarm 1, 2, 3 or 4” showing in display	Controller is simulating alarms (see Section 5.4)

16.11 SIMULATING INPUTS - DISSOLVED OXYGEN

To check the performance of the controller, use a decade box to simulate the current from the oxygen sensor.

A.Disconnect the anode and cathode leads from terminals 1 and 2 on TB3 and connect a decade box as shown in Figure 15-1. It is not necessary to disconnect the RTD leads.

B.Set the decade box to the resistance shown in the table.

Sensor	Polarizing Voltage	Resistance	Expected current
499ADO	-675 mV	34 kΩ	20 μA
499A TrDO	-800 mV	20 kΩ	40 μA
Hx438 and Gx448	-675 mV	8.4 MΩ	80 nA

C.Note the sensor current. To view the sensor current from the main display, press any key to enter the main menu. Move the

cursor to "Diagnostics" and press Enter (F4). The sensor cur- rent is the second line in the display. Note the units: μA is microamps, nA is nanoamps.

D.Change the decade box resistance and verify that the correct current is shown. Calculate current from the equation:

voltage (mV)

current (μA) =

resistance (kΩ)

FIGURE 16-1. Simulate Dissolved

Oxygen

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