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9. Trouble shooting
Fault symptom
Change in input signal to positioner does
not affect actuator position.
Change in input signal to positioner ma-
kes actuator move to its end position.
Inaccurate positioning.
Action
• Check air supply pressure and connection
between positioner and actuator.
• Check input signal to positioner.
• Check output signal from I/P converter.
• Check mounting and connections of po-
sitioner and actuator.
• Check function of diaphragm block.
• Check input signal.
• Check mounting and connections of po-
sitioner and actuator.
• Uneven air supply pressure.
•Uneven input signal.
• Wrong size of actuator being used.
• High friction in actuator/valve package.
• Excess play in actuator/valve package.
• Excess play in mounting of positioner
on actuator.
• Defect or leaking diaphragm block.