Monitoring The Number Of Changes In Direction; Monitoring The Lower Endstop / 7 Monitoring The Upper Endstop; Monitoring Deadband; Partial Stroke Test - Siemens SIPART PS2 Operating Instructions Manual

11.3.4.5

5 Monitoring the number of changes in direction

The diagnostics value "2 CHDIR" is constantly compared with the thresholds that are
determined from the "O1.LIMIT" to "O4.FACT3" parameters. If the thresholds are exceeded,
the fault message output or the alarm outputs respond depending on the mode of the extended
diagnostics. These two functions can be deactivated using the parameter setting "OFF" for "O.
DCHG".
11.3.4.6

6 Monitoring the lower endstop / 7 Monitoring the upper endstop

If the parameter "F. ZERO" is set to "ON", monitoring of the lower endstop is activated. 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 endstop 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 an error 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").
Similar diagnostics is carried out for the upper endstop. The "G. OPEN" parameter is used to
set the limit for this. The activation of "up tight closing" ("YCLS" parameter) is therefore the
condition.
11.3.4.7

8 Monitoring deadband

If the deadband 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 deadband monitoring). An error message output is activated
when this value is exceeded.
11.3.4.8

9 Partial stroke test

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 starting tolerance. On
the other hand, the fault message appears when one of the three thresholds of the partial
stroke test that are determined from the 'A9.PSTIN' reference stroke time multiplied by factors
'AA.FACT1', 'Ab.FACT2' and 'AC.FACT3' is violated. The severity of the fault message is
shown by the number of bars on the display. The severity of the fault message is simultaneously
SIPART PS2 with PROFIBUS PA
Operating Instructions, 02/2016, A5E00127926-AB
Alarm, fault and system messages
11.3 Online diagnostics
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