Learning Siemens valve positioner tuning (initialization) from diagrams

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The working principle of the Siemens SIPART PS2 intelligent electrical valve positioner is completely different from that of traditional positioners. A microprocessor is used to compare the set value with the position feedback. If the microprocessor detects a deviation, it uses a five-step switching procedure to control the piezoelectric valve, which in turn adjusts the air flow entering the actuator’s air chamber. When SIPART PS2 is connected in a two-wire configuration, it obtains its power entirely from the 4-20mA signal. Power can also be obtained from the PROFIBUS (SIPART PS2 PA) bus signal. The Siemens SIPART PS2 valve positioner is fixed to linear or rotary actuators using appropriate mounting components. The linear or angular displacement of the actuator is detected by these mounting components and converted by a rigidly connected conductive plastic potentiometer. The angular error detected by the components mounted on the linear actuator is automatically corrected. The microprocessor outputs an electrical control command to the piezoelectric valve based on the magnitude and direction of the deviation (between the set value W and the position feedback signal X). The piezoelectric valve converts control commands into pneumatic displacement increments, especially when the control error is large (in the high-speed range). The locator outputs a continuous signal ； When the control deviation is small (low-speed range), the output pulses of the positioner are continuous ； When the controller deviation is very small (in adaptive or adjustable deadband mode), no control command is output. http://yunrun.com.cn/upload/201811/14/201811140222293963.png Calibration of the SIPART PS2 valve positioner: yunrun.com.cn/product/ The calibration (initialization) of the Siemens SIPART PS2 intelligent electrical valve positioner is carried out automatically to a large extent. During initialization, the microprocessor automatically determines the zero point of the actuator, its maximum travel distance, the direction of action, and the positioning speed of the actuator; these values are used to determine the minimum pulse duration and dead zone, thereby achieving optimal control. The buttons and LCD on the SIPART PS2 locator can be used to manually operate the pneumatic actuator. ①The monitoring and diagnostic functions of SIPART PS2 (6DR5...) for positioners, actuators, and control valves include various monitoring capabilities for detecting changes in these components; when extreme value alarms are selected, it can report on such changes. Such diagnostics provide important information regarding control valves and actuators. ②It enables the determination and monitoring of measured values (with some extreme values adjustable), including: ◆ Travel accumulation ◆ Number of direction changes ◆ Alarm count ◆ Dead zone self-adjustment ◆ Limit positions of the valve (e.g., seat wear) ◆ Operating hours at maximum/minimum temperatures (based on temperature rating) ◆ Number of operation cycles of the piezoelectric valve ◆ Valve positioning time ◆ Actuator leakage. For a new SIPART PS2 intelligent valve positioner or one that has been offline for an extended period, it is necessary to reset the parameters and perform initialization so that it meets the requirements for use; otherwise, the valve positioner will not function properly. Parameter setting of the SIPART PS2 valve positioner: ① After the SIPART PS2 valve positioner is powered on, the following is displayed: http://yunrun.com.cn/upload/201811/14/201811140203237838.png http://yunrun.com.cn/upload/201811/14/201811140204465171.png At this point, the actuator can be moved using the up and down buttons to each end position, in order to check whether the mechanical mechanism can move freely throughout its entire range of adjustment. For linear stroke actuators, when the rod is brought to a horizontal position, the display will show a value between P48.0 and P52.0. If this is not the case, adjust the friction clamping unit until the rod is horizontal and “P50.0” is displayed. To be precise, once you reach this value, the displacement that can be measured by the locator will be more accurate. Note: By keeping the first direction key pressed downward while pressing another direction key, you can move the actuator quickly. http://yunrun.com.cn/upload/201811/14/201811140027267649.png ②Parameter 1 (selecting the type of actuator) http://yunrun.com.cn/upload/201811/14/201811140034095728.png http://yunrun.com.cn/upload/201811/14/201811140038481482.png ③Parameter 2 (selecting the rotation angle of the actuator) http://yunrun.com.cn/upload/201811/14/201811140045285752.png Note: The position of the leverage ratio switch is very important for the locator; this parameter must match the setting value of the leverage ratio switch. http://yunrun.com.cn/upload/201811/14/201811140051172660.png http://yunrun.com.cn/upload/201811/14/201811140058161643.png http://yunrun.com.cn/upload/201811/14/201811140101481790.png ④Parameter 3 (indicating the range of the valve stem) http://yunrun.com.cn/upload/201811/14/201811140107065158.png http://yunrun.com.cn/upload/201811/14/201811140110013111.png http://yunrun.com.cn/upload/201811/14/201811140113066992.png If you want to know the total stroke length calculated after initialization, expressed in mm, this parameter must be set. To do this, you need to select on the display screen a value that is the same as the set value of the driving pin on the scale rod. Automatic initialization of the SIPART PS2 intelligent electrical valve positioner ⑤Parameter 4 (indicating automatic initialization): http://yunrun.com.cn/upload/201811/14/201811140116343804.png http://yunrun.com.cn/upload/201811/14/201811140119329713.png http://yunrun.com.cn/upload/201811/14/201811140122411477.png http://yunrun.com.cn/upload/201811/14/201811140125177817.png The specific meaning of the five steps in the initialization process of the SIPART PS2 valve positioner can be seen in the examples above. No action is required during this period. If a failure occurs at any step, handle it according to the procedures in Section 3. Note: The initialization process depends on the actuator and can last up to 15 minutes. http://yunrun.com.cn/upload/201811/14/201811140138522520.png ⑥Manual initialization of the SIPART PS2 valve positioner: Setting the first position for manual initialization: http://yunrun.com.cn/upload/201811/14/201811140150115144.png Setting the second position for manual initialization: Special note: Manual initialization is used only in a few specific cases. For most applications, automatic initialization is sufficient.