Emerson PN 51-FCL-1056 Troubleshooting When no Error Message is Showing General, Anod, Cath

MODEL FCL-1056		SECTION 9.0
		TROUBLESHOOTING
9.7 TROUBLESHOOTING WHEN NO ERROR MESSAGE IS SHOWING — GENERAL
	Problem	See Section
	New temperature during calibration more than 2-3C° different	9.7.1
	from live reading
	Current output is too low	9.7.2
	Alarm relays do not operate when setpoint is exceeded	9.7.3

9.7.1 Difference Between Analyzer and Standard Thermometer is Greater Than 3°C.

1.Is the standard thermometer, RTD, or thermistor accurate? General purpose liquid-in-glass thermometers, particularly ones that have been mistreated, can have surprisingly large errors.

2.Is the temperature element in the pH sensor completely submerged in the test liquid?

3.Is the standard temperature sensor submerged to the correct level?

4.Review Section 6.2.

9.7.2 Current Output Too Low.

Load resistance is too high. Maximum load is 550 Ω.

9.7.3Alarm Relays Do Not Work Verify the relays are properly wired.

9.8 SIMULATING INPUTS — CHLORINE

To check the performance of the analyzer, use a decade box and 1.5V battery to simulate the current from the sen- sor. The battery, which opposes the polarizing voltage, is necessary to ensure that the sensor current has the correct sign.

1.Disconnect the anode and cathode leads from terminals 1 and 2 on TB3 and connect a decade box and 1.5V battery as shown in Figure 9-3. It is not necessary to disconnect the RTD leads.

2.Set the decade box to 2.8 MΩ.

3.Note the sensor current. It should be about 500 nA. The actual value depends on the voltage of the battery. To view the sensor cur- rent, go to the main display and press DIAG. Choose sensor 1. The input current is the second line in the display. Change the decade box resistance and verify that the correct current is shown. Calculate current from the equation:

	7	ANOD SHLD
	8	ANOD
R	9	CATH SHLD

current (nA) =

Vbattery — 200 (voltages in mV)

resistance (MΩ)

10 CATH

The voltage of a fresh 1.5 volt battery is about 1.6 volt (1600 mV).

FIGURE 9-3. Simulating Chlorine

70