ROTORK /YCT  YT3300  Series - YT-3300RDI5525S

The YT3300 series Smart Valve Positioner works by receiving a 4-20mA input signal from a controller and using a built-in microprocessor to accurately control the valve's stroke. It translates the input signal into precise mechanical movement, which is then optimized by the microprocessor through functions like auto-calibration and PID control, ensuring the valve is in the correct position. The device uses a feedback mechanism to monitor the actual valve position and adjust accordingly to meet the desired command from the controller.

Working principle breakdown

• Receives input: The positioner takes a standard 4-20mA signal from a control system.
• Microprocessor interprets: A built-in microprocessor reads this signal and, using programmed algorithms, determines the precise position the valve should be in.
• Calculates required action: The microprocessor compares the desired position with the actual valve position and calculates the necessary adjustments. It can also perform additional functions like PID control for more sophisticated regulation or auto-calibration to set the zero and span of the valve stroke.
• Controls air pressure: The positioner then uses internal components to direct pneumatic pressure to either open or close the valve, moving it to the commanded position.
• Feeds back position: A feedback lever connects the positioner to the valve actuator, continuously sending information on the valve's current position back to the microprocessor. This creates a closed-loop system that constantly monitors and corrects for any deviations.
• Communicates status: An LCD display shows the positioner's status, and the device can communicate with other systems using protocols like HART.

Working principle

The YT-3300 positioner operates as a closed-loop control system to ensure the valve position matches the commanded signal. The principle is as follows:

1. Receives the command signal: The positioner receives a 4–20 mA current signal from a controller or control system. This electrical signal represents the desired valve position.
2. Analyzes the position: A microprocessor compares the input signal with the actual valve position, which is monitored by a mechanical feedback lever connected to the valve stem.
3. Adjusts the pneumatic output:

• If the actual valve position does not match the command signal, the positioner adjusts the air pressure in the pneumatic actuator.
• For a single-acting actuator, the positioner controls the pressure to a single port.
• For a double-acting actuator, it manages the pressure to two ports to control movement in both directions.

4. Moves the valve: The change in air pressure causes the actuator to move the valve stem until it reaches the correct position.
5. Achieves equilibrium: The positioner will continue to regulate the air pressure until the feedback signal confirms that the valve's position perfectly matches the commanded 4–20 mA signal, effectively closing the control loop.

Advanced features

The "smart" microprocessor at the core of the YT-3300 enables the following capabilities:

• Auto-calibration: The positioner can automatically set its zero and span, simplifying commissioning.
  PID control: Proportional-integral-derivative (PID) control can be used to optimize the positioner's response.
• HART communication: This protocol allows for two-way communication over the 4–20 mA loop, providing diagnostic information and configuration options.
• Variable characteristics: The positioner can be configured with different flow characteristics, such as linear, quick opening, or equal percentage, to match the process requirements.
• Split range: The input signal range can be split, allowing one positioner to respond to 4–12 mA and another to 12–20 mA.
• Manual operation: A manual switch can be used to bypass the automatic control and operate the valve manually.

 Full Datasheet

Positioner Transmitter Feature   YT-3300RDI5525S

Basic Ordering Information