Siemens SIPART PS2 6DR50 Series, Manual

Page: 134 / 160

Operation
134
SIPART PS2 Manual
A5E00074631--06
4 Stroke number monitoring
5 Monitoring of the number of changes of direction
The two values, number of strokes and number of changes of direction,
are compared to the threshold values on a continuous basis. These
values result from the parameters “L1.LIMIT” to “L4.FACT3” and
“O1.LIMIT” to “O4.FACT3”. If they are exceeded, depending on the
operating mode of the extended diagnostics, the fault message output
reacts, and possibly also the alarm outputs. The two functions can
be deactivated by the parameter setting “OFF” for “L. STRK” or
“O. DCHG”.
6 Monitoring of the lower limit stop (valve seat)
7 Monitoring of the upper limit stop
The monitoring of the lower limit stop is activated if parameter
“F. ZERO” has a value
¸
OFF. This function can be used e.g.
to detect valve seat errors. If the limit is exceeded, this can be an
indication of deposits or foreign particles on the valve seat. If the limit is
fallen short of, wear to the valve seat or reactor body could be the
cause. The mechanical misadjustment of the position feedback can
also trigger this error message.
Monitoring takes place every time the valve is in “bottom tight closing”
position. In doing so, the current position is compared to the position
that was determined as lower end stop during the initialization phase.
The activation of the “bottom tight closing function” (parameter
“39.YCLS”) is therefore prerequisite.
Example: 3% is set as value. For “bottom tight closing”, the 0% position
is normally established. If a value of >3% or <--3% is determined
instead, a fault is reported.
The fault message remains activated until either a subsequent
monitoring process remains within the tolerance range or a
re-initialization is carried out. The deactivation of the monitoring
process (“F. ZERO”=OFF) also deletes any fault messages.
This monitoring function does not provide any useful results if the stops
were not determined automatically during initialization but instead the
limits were set by hand (manual initialization, “5.INITM”).
An appropriate diagnosis was carried out for the upper limit stop. The
parameter “G. OPEN” is used to set this limit. The activation of the
“top tight closing function” (parameter “39.YCLS”) is therefore
prerequisite.
8 Dead zone adaptation monitoring
If, during the automatic adaptation of the dead zone (parameter
34.DEBA=Auto) the dead zone increases disproportionately during
operation, this is an indication of a fault in the system (e.g. significantly
increased stuffing box friction, play in the position displacement sensor,
leakage). Therefore a limit can be specified for this value (“E1.LEVL3”,
threshold for dead zone monitoring) that activates the fault message
output if it is exceeded.