ROTORK /YCT  YT-2501  Series - YT-2501LSI3220F1

The YT-2501 is a smart valve positioner that uses a remote sensor to precisely control a valve's position based on an input signal, like a 4-20mA current loop. It works by using a closed-loop feedback system: the sensor measures the valve's actual position, and the positioner adjusts the pneumatic pressure to the actuator to move the valve to the desired position. A key feature is the remote sensor, which separates the position sensing from the positioner unit, allowing it to be installed in locations with excessive heat or vibration.

Core working principle

• Sensing: A remote sensor measures the real-time position of the valve stem (either linear or rotary).
• Communication: The sensor sends this position data to the positioner via a dedicated communication cable.
• Comparison: The positioner compares the actual valve position to the commanded position from the control system (e.g., a PLC).
• Control: It then uses its internal PID (Proportional-Integral-Derivative) control logic to calculate the necessary adjustments.
• Actuation: Based on the PID calculation, it sends pneumatic pressure to the actuator to move the valve to the correct position.

Key features contributing to the working principle

• PID Control: The positioner uses a PID control algorithm to achieve precise and stable valve positioning.
• Auto Calibration: This feature simplifies the setup by automatically finding the zero and end points of the valve.
• Fail Freeze/Safe: In case of power or air supply loss, the valve can be set to either "fail freeze" (maintain its last position) or "fail safe" (move to a predetermined position).
• HART Communication: This protocol allows for two-way communication, enabling remote configuration, diagnostics, and valve position feedback

Core operating principle

The YT-2501 uses a sophisticated control loop to ensure the valve position matches the setpoint from a controller. The process involves four key steps:

• Input signal and microprocessor: A control system sends a 4–20 mA DC analog signal to the YT-2501. The positioner's built-in microprocessor receives this signal and interprets it as the desired valve position.
• Position sensing and feedback: The remote position sensor, connected to the valve actuator, continuously measures the actual valve position (stroke). It sends this feedback signal back to the microprocessor in the main positioner unit.
• Proportional-Derivative (PD) control: The microprocessor executes a PD control algorithm, comparing the desired valve position from the input signal with the actual position reported by the remote sensor. It calculates any error and determines the necessary adjustment to the air pressure.
• Pneumatic output: The microprocessor drives an internal pilot valve, which uses the clean air supply to regulate the pressure sent to the actuator. If the valve needs to open further, the output pressure increases; if it needs to close, the pressure decreases.

This process forms a high-accuracy, closed-loop system that ensures the valve holds its commanded position, even with changes in process conditions or supply pressure.

Advanced features and reliability

The YT-2501's design and software give it several advantages over older valve positioners:

• Separated feedback module: The remote sensor allows the main processing unit to be installed in a safer, more accessible location, which reduces the risk of damage from high temperatures or strong vibrations.
• Low air consumption: The positioner is designed for extremely low air consumption in a steady state, which significantly reduces the energy costs of large-scale operations.
• Smart features: It includes advanced capabilities like:

• Auto-calibration: Automates the setup process to quickly and accurately calibrate the positioner to the specific valve and actuator.
• HART communication: This protocol allows for digital communication over the 4–20 mA signal line, providing remote configuration, diagnostics, and monitoring.

• Fail-safe functions: The YT-2501 can be configured for fail-freeze or fail-safe behavior. This means the valve will either lock in its last position or move to a preset position if the electrical or air supply is lost.

 Full Datasheet

Positioner Transmitter Feature   YT-2501LSI3220F1

Basic Ordering Information