Siemens SIMATIC PCS 7 Monitoring and diagnostics for positioners and valves, Sitrans VP300

© Siemens AG 2011

Monitoring and diagnostics for positioners and valves

SITRANS VP300 and SIPART PS2 are intelligent electro- pneumatic positioners for control valves and two-position valves in the process industry. Both devices can be used very flexibly in various processes.

In addition to the standard function of each positioner, i.e. controlling process valves, both devices also have comprehen- sive diagnostic functions, which can indicate critical statuses of the drive or valve at any time during operation of the plant.

The following functions are available in both devices:

•Slow movement of a valve

•Clogging of a pipeline

•Tear-off of the valve plug

•Wear of the valve seat or valve plug

•Adhesion of the stuffing box

•Partial stroke test for two-position valves

In addition, both devices offer other individual functions for detecting critical statuses of the control valve:

SITRANS VP300

For detecting positions, the device uses a permanent magnet on the spindle of the drive and sensors in the interior of the positioner. If the magnet is physically moved or missing, this is detected and signaled by the positioner. In addition, the Par- tial Stroke Test is optionally SIL-certified.

SIPART PS2

In addition to detecting pneumatic leaks, the device is also ca- pable of performing a solenoid valve test. If a suitable soleno- id valve is used, it is thus possible to make a reliable statement about the correct functioning of the connected solenoid val- ve.

These faults are reported based on their severity and, conse- quently, the urgency of maintenance they require using the 3- stage evaluation scale of the SIMATIC PCS 7 Maintenance Sta- tion. The faults are also displayed and analyzed on the on-site display. Thus, faults can be detected early, long before failures or even plant stoppages occur.

With regard to preventive maintenance measures, the fol- lowing values are also monitored and a 3-stage message can sometimes be output, as described above:

•Operating hours (also differentiated by temperature ran- ges and adjusting ranges)

•Operating temperature, current and min./max.

•Stroke counter (stroke integral)

•Number of changes in direction

The most important status parameters can be visualized using a suitable HMI tool (e.g. SIMATIC PDM) both in trend view and in histogram view.

The benefits of predictive maintenance are based on the fact that the corresponding components can be used for their en- tire service life without the risk of failure or damage. The dia- gnostic functions in SITRANS VP300 and in SIPART PS2 also help with the early detection of impending damage to the drive or valve, which can lead to a plant stoppage in the worst case scenario. Thus, information can be gained from the load factor, which can be used to optimize the way in which the plant is operated or for advance maintenance. In total, this leads to an increase in the availability of the entire plant.

SIPART PS2 and SITRANS VP300 POSITIONERS

SITRANS VP300 and SIPART PS2 offer a standard Partial Stroke Test in order to extend the maintenance interval of two-position valves

Monitoring and diagnostics 21