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Alarm, fault and system messages
12.3 Online diagnostics
4 Monitoring of the stroke number
5 Monitoring of the number of changes of direction
Both the values, namely the stroke number and the number of changes of direction are
constantly compared with the thresholds that are determined from the parameters "L1.LIMIT"
to "L4.FACT3" and "O1.LIMIT" to "O4.FACT3". If the thresholds are exceeded, the fault
message output or the alarm outputs respond depending on the mode of the advanced
diagnostics. Both these functions can be deactivated using the parameter setting "OFF" for
"L. STRK" and "O. DCHG".
6 Monitoring of the lower hard end stop (valve seat)
7 Monitoring of the upper hard end stop
The monitoring of the lower hard end stop is activated when the value of the "F. ZERO"
parameter is "OFF". This function can be used to detect the errors in the valve seat. An
overshot limit indicates the possibility of deposits or foreign bodies in the valve seat. An
undershot limit indicates probable wear and tear of the valve seat or flow restrictor. Even a
mechanical misalignment of the position feedback can trigger this fault message.
Monitoring is always carried out whenever the valve is in the "down tight closing" position.
The current position is compared with the position that was determined as the lower end stop
at the time of initialization. The activation of "down tight closing" ("YCLS" parameter) is
therefore the condition.
Example: A value of 3% is set. The position is normally adopted for "down tight closing". A
fault is reported if a value > 3% or < -3% is determined instead.
The fault message remains activated until either a subsequent monitoring remains within the
tolerance or a re-initialization process is executed. Even the deactivation of monitoring
("F. ZERO"=OFF) may trigger a fault message.
This monitoring function does not deliver any utilizable results if the end stops were not
determined automatically at the time of initialization, but the limits were set manually (manual
initialization, "5.INITM").
A similar diagnostics is carried out for the upper hard end stop. The "G. OPEN" parameter is
used to set the limit for this. The activation of "up tight closing" ("YCLS" parameter) is
therefore the condition.
8 Monitoring of dead zone adjustment
If the dead zone increases disproportionately when adjusting it automatically ("DEBA"=Auto
parameter), it indicates an error in the system (e.g. severely increased packing gland friction,
play in the position displacement sensor, leakage). A limit can therefore be entered for this
value ("E1.LEVL3", threshold for dead zone monitoring). A fault message output is activated
when this value is exceeded.
9 Partial stroke test exceeds the reference step time
On the one hand, this fault message appears when a manual or cyclic partial stroke test is
initiated and the test cannot be started since the valve is not within the start tolerance. On
the other hand, this fault message appears when one of the three thresholds of the partial
234
SIPART PS2 with PROFIBUS communication
Operating Instructions, 09/2007, A5E00127926-07
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