Off Line Diagnostics; On Line Diagnostics - GE Baker Hughes Masoneilan SVI FF Installation And Operation Manual

Off Line Diagnostics

Off Line diagnostics are used when the application process is not running. Off-line diagnostics
procedure execution requires significant changes of valve setpoint, which disturbs the
application process.
When off Line diagnostic procedures are executed, the data is collected in the SVI FF
positioner at a very high rate (e.g. between 10 and 60 times per second) and then it is
uploaded and presented by the SVI FF DTM.
Step Test
The step test evaluates how the positioner is responding on a request to change in the set
point significantly for a short time. It gives a good measure of the actuator/valve speed.
Ramp Test
The ramp test measures the relationship between the set point and actual actuator/valve
position, when the setpoint is changed at a limited rate.
Signature
The Valve Signature provides a relationship between the actuator pressure and the actuator/
valve actual position.

On Line Diagnostics

On Line diagnostic procedures collect data while the valve is running and do not disturb the
application process. Special tools are used to collect the data from the valve, evaluate
performance and present the information.
DTM
The SVI FF DTM can provide a basic level of online diagnostic by presenting the data from the
positioner in numeric or graphical form. You can also export the data for further analysis with
external tools.
Valve Aware
Valve Aware provides advanced diagnostic procedures. It collects data from the positioner on
a regular basis and stores it for further evaluation without any human interaction. The
processing and storage power provided by the contemporary computers detects:
Change in valve/positioner friction
Stick slip in the valve
Changes in dynamic behavior, etc.
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