Troubleshooting the flow element – Fluid Components International FLT93 Nuclear User Manual

Page 42

TROUBLESHOOTING FLT

Series FlexSwitch

Fluid Components International LLC

If conditions and specifi cations are satisfactory, then refer to the troubleshooting chart in the back of this chapter for troubleshooting
suggestions.

Troubleshooting the Flow Element

Use Tables 5-1 and 5-2 to determine if the fl ow element is wired correctly or has failed. Turn off the input power to the instrument. Unplug
the control circuit from its socket and measure the resistances below from the terminal block socket.

If the instrument is set up in remote confi guration (fl ow element enclosure seperate from the control circuit enclosure), and the ohm readings
are incorrect, disconnect the fl ow element cable at the local (fl ow element) enclosure. Measure the resistance as shown in Table 5-2. If the
resistances are correct then the cable between the enclosures is probably bad or not connected properly (loose, corroded, or connected to the
wrong terminals).

For normally dry conditions check for moisture on the sensing element. If a component of the process media is near its saturation tempera-
ture it may condense on the sensing element. Place the sensing element where the process media is well above the saturation temperature
of any of the process gases.

NOMINAL CONTROL CIRCUIT RESISTANCE

LUG NUMBER

RESISTANCE

7 TO 8

1.1 K OHM*

7 TO 9

2.2 K OHM*

7 TO 10

110-120 OHM FOR FLT93-S

548-620 OHM FOR FLT93-F

8 TO 9

1.1 K OHM*

Table 5-1. Resistance at Control Circuit Terminal Block Socket

NOMINAL RESISTANCE AT LOCAL ENCLOSURE TERMINAL BLOCK

TERMINAL NO.

RESISTANCE

1 TO 2

110-120 OHM FOR FLT93-S

548-620 OHM FOR FLT93-F

3 TO 4

1.1 K OHM*

3 TO 5

2.2 K OHM*

4 TO 5

1.1 K OHM*

SHIELD CONNECTED TO CONTROL CIRCUIT SOCKET ONLY. NO

CONNECTION TO LOCAL ENCLOSURE OR ITS TERMINAL BLOCK**

Table 5-2. Resistance at Flow Element enclosure Terminal Block (Remote Applications Only)

* Approximate at 80°F process temperature.

** Reference wiring diagrams in the Installation section of the manual.