Rosemount Model 3095 Multivariable
™
Level Controller
5-2
LEVEL CONTROLLER
TROUBLESHOOTING
If a malfunction is suspected, follow the procedures described here to
verify that device hardware and process connections are in good
working order. Under each major symptom, specific suggestions are
offered for solving the problem. Always deal with the most likely and
easiest-to-check conditions first.
Communication Problems
Table 5-1 identifies the most likely causes for communication problems
between the Model 275 HART Communicator and the Level Controller.
TABLE 5-1. Device Does not
Communicate with the HART
Communicator.
Process leaks could result in death or serious injury:
• Install only the flange adapter O-ring designed to seal with the corresponding
flange adapter.
High voltage that may be present on leads could cause electrical shock:
• Avoid contact with leads and terminals.
Symptom Corrective Action
No Communication
between the HART
Communicator and the
Level Controller
LOOP WIRING
• HART protocol communication requires a loop resistance
value between 250–1100 ohms, inclusive.
• Check for adequate voltage to the device. (If the HART
Communicator is connected and 250 ohms resistance is
properly in the loop, a power supply voltage of at least 16.5 V
dc plus actuator voltage drop is required.) There must be at
least 11V dc at the device terminals.
• Check for intermittent shorts, open circuits, and
multiple grounds.
• Check for capacitance across the load resistor. Capacitance
should be less than 0.1 microfarad.
• If no device is connected across the “OUT” terminals, the
terminals must be shorted (jumpered) together.
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