ROTORK /YCT  YT-3400  Series - YT-3400RDZ5501S

The YT-3400 is a smart valve positioner that accurately controls a valve's position based on a 4-20mA input signal from a controller. Its internal micro-processor optimizes performance through features like auto-calibration, PID control, and HART communication, allowing it to adjust valve characteristics, such as linear, quick open, or equal percentage. The YT-3400 receives a signal, determines the desired valve position, and uses a compressed air supply to move the valve to that position, providing a feedback signal to confirm the valve's status.

How it works

• Receiving the signal: The positioner receives a \(4-20mA\) input signal from a control system, which represents the desired valve position.
• Processing the signal: A micro-processor inside the positioner interprets this signal.Controlling the valve: Based on the signal, the positioner sends compressed air to either the top or bottom of a pneumatic actuator to move the valve stem to the correct position.
• Feedback and fine-tuning: An internal sensor continuously monitors the valve's actual position and provides feedback to the processor. The processor can then make fine adjustments to ensure the valve is in the exact position commanded by the input signal. 

Key features and functions

• Auto-calibration: Simplifies the setup process by automatically learning the valve's stroke and setting parameters.
• PID control: Allows for precise control and adjustment of the valve's position using Proportional-Integral-Derivative control loops.
• HART communication: Enables two-way digital communication for advanced diagnostics, parameter adjustments, and status monitoring, all without opening the cover in hazardous areas.
• Customizable valve characteristics: Allows users to set specific relationships between the input signal and valve position, such as linear, quick open, or equal percentage.
• Diagnostics: Includes alarms and other diagnostic capabilities, with the option to monitor the positioner's condition via an external LCD.
• Manual override: A switch allows for manual operation or direct air supply to the actuator without using the control signal.

Key components and signal flow

1. Input signal: The YT-3400 receives a standard 4–20 mA electrical current signal from a control system, such as a Distributed Control System (DCS). The 4 mA signal corresponds to the valve being fully closed, and 20 mA corresponds to the valve being fully open.
2. Micro-processing unit: The positioner's built-in microprocessor reads and interprets the input signal, treating it as the desired set point for the valve's position.
3. Position feedback: The YT-3400 uses a non-contact sensor to monitor the current physical position of the valve stem or shaft. This feedback is crucial for closing the control loop.
4. Comparison and control: The microprocessor compares the input set point from the controller with the actual valve position reported by the sensor. Based on the difference, it calculates the necessary correction using PID (Proportional-Integral-Derivative) control algorithms.
5. Pneumatic output: The positioner then modulates its pneumatic output pressure to the actuator. If the valve is not open far enough, it increases pressure; if it is too far open, it decreases the pressure.
6. Actuator movement: The air pressure from the positioner acts on the actuator, causing it to move and adjust the valve position.
7. Closed-loop correction: The position feedback sensor continuously reports the valve's updated position back to the microprocessor, which again compares it to the input signal. This constant loop of sensing, calculating, and correcting ensures the valve quickly and accurately reaches and holds the commanded position.

Features that enhance the working principle 

• Non-contact sensor: Modern YT-3400 positioners use a non-contact sensor, which improves accuracy and stability by eliminating mechanical hysteresis and wear common with gear-based systems.
• PID control: The advanced PID algorithms allow the positioner to perform better than older, conventional positioners by minimizing overshooting and hunting (oscillations around the set point).
• Auto-calibration: An automated calibration function simplifies setup by automatically detecting and adjusting the zero and end points of the valve's travel.
• HART communication: The positioner can use the HART protocol to superimpose digital information on the 4–20 mA analog signal. This allows for remote configuration, diagnostics, and monitoring without interrupting the control signal.
• Auto/Manual switch: A physical switch on the positioner allows operators to directly supply air to the actuator for manual operation, bypassing the electronic control system for troubleshooting or maintenance.

 Full Datasheet

Positioner Transmitter Feature   YT-3400RDZ5501S

Basic Ordering Information 

ROTORK /YCT  YT-3400  Series - YT-3400LSZ3520S

The YT-3400 is a smart valve positioner that accurately controls a valve's position based on a 4-20mA input signal from a controller. Its internal micro-processor optimizes performance through features like auto-calibration, PID control, and HART communication, allowing it to adjust valve characteristics, such as linear, quick open, or equal percentage. The YT-3400 receives a signal, determines the desired valve position, and uses a compressed air supply to move the valve to that position, providing a feedback signal to confirm the valve's status. 

How it works

• Receiving the signal: The positioner receives a \(4-20mA\) input signal from a control system, which represents the desired valve position.
• Processing the signal: A micro-processor inside the positioner interprets this signal.Controlling the valve: Based on the signal, the positioner sends compressed air to either the top or bottom of a pneumatic actuator to move the valve stem to the correct position.
• Feedback and fine-tuning: An internal sensor continuously monitors the valve's actual position and provides feedback to the processor. The processor can then make fine adjustments to ensure the valve is in the exact position commanded by the input signal. 

Key features and functions

• Auto-calibration: Simplifies the setup process by automatically learning the valve's stroke and setting parameters.
• PID control: Allows for precise control and adjustment of the valve's position using Proportional-Integral-Derivative control loops.
• HART communication: Enables two-way digital communication for advanced diagnostics, parameter adjustments, and status monitoring, all without opening the cover in hazardous areas.
• Customizable valve characteristics: Allows users to set specific relationships between the input signal and valve position, such as linear, quick open, or equal percentage.
• Diagnostics: Includes alarms and other diagnostic capabilities, with the option to monitor the positioner's condition via an external LCD.
• Manual override: A switch allows for manual operation or direct air supply to the actuator without using the control signal.

Key components and signal flow

1. Input signal: The YT-3400 receives a standard 4–20 mA electrical current signal from a control system, such as a Distributed Control System (DCS). The 4 mA signal corresponds to the valve being fully closed, and 20 mA corresponds to the valve being fully open.
2. Micro-processing unit: The positioner's built-in microprocessor reads and interprets the input signal, treating it as the desired set point for the valve's position.
3. Position feedback: The YT-3400 uses a non-contact sensor to monitor the current physical position of the valve stem or shaft. This feedback is crucial for closing the control loop.
4. Comparison and control: The microprocessor compares the input set point from the controller with the actual valve position reported by the sensor. Based on the difference, it calculates the necessary correction using PID (Proportional-Integral-Derivative) control algorithms.
5. Pneumatic output: The positioner then modulates its pneumatic output pressure to the actuator. If the valve is not open far enough, it increases pressure; if it is too far open, it decreases the pressure.
6. Actuator movement: The air pressure from the positioner acts on the actuator, causing it to move and adjust the valve position.
7. Closed-loop correction: The position feedback sensor continuously reports the valve's updated position back to the microprocessor, which again compares it to the input signal. This constant loop of sensing, calculating, and correcting ensures the valve quickly and accurately reaches and holds the commanded position.

Features that enhance the working principle 

• Non-contact sensor: Modern YT-3400 positioners use a non-contact sensor, which improves accuracy and stability by eliminating mechanical hysteresis and wear common with gear-based systems.
• PID control: The advanced PID algorithms allow the positioner to perform better than older, conventional positioners by minimizing overshooting and hunting (oscillations around the set point).
• Auto-calibration: An automated calibration function simplifies setup by automatically detecting and adjusting the zero and end points of the valve's travel.
• HART communication: The positioner can use the HART protocol to superimpose digital information on the 4–20 mA analog signal. This allows for remote configuration, diagnostics, and monitoring without interrupting the control signal.
• Auto/Manual switch: A physical switch on the positioner allows operators to directly supply air to the actuator for manual operation, bypassing the electronic control system for troubleshooting or maintenance.

 Full Datasheet

Positioner Transmitter Feature   YT-3400LSZ3520S

Basic Ordering Information 

ROTORK /YCT  YT-3302  Series - YT-3302LDI222001

The Rotork YT-3302 Series smart valve positioner uses a 4-20mA input signal to precisely control a valve's position by comparing the input signal to the valve's actual position. It features a built-in microprocessor that runs an automated calibration to set the valve's zero and span, executes PID control for accurate performance, and can be controlled manually via front-panel buttons. It also communicates digitally via the HART protocol for diagnostics and status information.play.

Key working principles:

• Signal input: The positioner receives a 4-20mA current signal from a controller, which represents the desired valve position.
• Microprocessor control: A built-in microprocessor interprets the input signal and determines the required position.
• Position feedback: It uses a sensor to measure the valve's current position.
• Pneumatic control: The microprocessor compares the desired position to the actual position and sends the correct pneumatic signal to a diaphragm actuator to move the valve stem.
• Auto-calibration: The unit can automatically calibrate its zero and span points, ensuring it accurately corresponds the 4-20mA signal to the full range of the valve's travel.
• PID control: It includes a configurable PID (Proportional-Integral-Derivative) control loop, which provides stable and accurate valve control by adjusting the output based on the error between the setpoint and the actual position.
• Manual/Automatic modes: It can operate in automatic mode based on the control signal or switch to manual mode for local operation or troubleshooting, allowing a user to move the valve directly using the front-panel buttons.
• HART communication: It uses the HART protocol to digitally transmit information over the same two wires as the 4-20mA signal, allowing for advanced diagnostics, remote configuration, and a position feedback signal.

The ROTORK YT-3302 is a smart electro-pneumatic valve positioner that works on a closed-loop feedback principle. It takes an analog electrical input signal (typically 4–20 mA) from a controller and accurately moves a pneumatic valve actuator to the corresponding position.
The YT-3302 differs from other YT-3300 series positioners in that it has a remote sensor, which allows it to be mounted away from extreme temperature or vibration, and uses a junction box for electrical connection.

Working principle

1. Input signal and microprocessor: A 4–20 mA DC electrical signal is sent from a central controller to the positioner's internal microprocessor. This signal represents the desired valve position (e.g., 4 mA = 0% open, 20 mA = 100% open).
2. Analog-to-Digital conversion: The electrical signal is converted to a digital signal by the positioner's internal 12-bit A/D converter.
3. Position sensing and feedback: The YT-3302 uses a potentiometer-type sensor to detect the current position of the valve stem. Because the sensor is mounted remotely from the main housing, it is connected via a cable. The feedback from this sensor is sent back to the microprocessor.
4. Error calculation and PID control: The microprocessor compares the input command signal (desired position) with the feedback signal (actual position). Any difference is the error. The positioner uses a Proportional-Integral-Derivative (PID) control algorithm to calculate the necessary pneumatic output to correct this error and move the valve to the desired position.
5. Digital-to-Analog conversion: The calculated output from the microprocessor is converted back to an analog electrical signal by a 12-bit D/A converter.
6. Electro-pneumatic conversion: The YT-3302 contains a torque motor and flapper-nozzle system. It converts the D/A output to a proportional pneumatic signal that controls the air flow to the valve actuator.
7. Pneumatic actuation: The pneumatic output signal from the positioner adjusts the air pressure in the actuator. This air pressure then moves the valve stem to the correct position.
8. Closed-loop repetition: The positioner constantly repeats this feedback loop, adjusting the air pressure to the actuator until the valve's actual position matches the command signal. This ensures high accuracy and stability, even with changes in process conditions like air pressure fluctuations, friction, and fluid dynamics.

Key features enhancing the working principle

• Remote sensor: The YT-3302's defining feature is its remote sensor, which allows the positioner's electronics to be isolated from high temperature and vibration environments near the valve.
• Auto calibration: The microprocessor-based design enables an auto-calibration function that automatically sets the zero and end points of the valve, simplifying commissioning.
• HART communication: The positioner supports HART protocol, enabling advanced diagnostics, remote configuration, and status monitoring over the existing 4–20 mA signal loop.
  PID control: The use of PID control allows for precise and fast response times, ensuring accurate and stable control of the valve.
• Selectable flow characteristics: The YT-3302 is configurable for various flow characteristics (e.g., linear, equal percentage) to match the needs of the specific process application.

 Full Datasheet

Positioner Transmitter Feature   YT-3302LDI222001

Basic Ordering Information 

ROTORK /YCT  YT-3303  Series - YT-3303LSI2500L

The Rotork YT-3303 series smart valve positioner uses a PID control loop and a torque motor/flapper nozzle mechanism to precisely control a valve's position based on a 4-20mA input signal from a controller. It continuously receives the signal, measures the actual valve position using a sensor, and uses the built-in microprocessor to send air to a pneumatic actuator, adjusting the valve to match the commanded position. Key features include auto-calibration, HART communication, and an LCD display.

Working principle breakdown

• Input and control signal: A controller sends a 4-20mA signal to the positioner, which represents the desired valve position.
• Microprocessor and sensor: The positioner's built-in microprocessor compares the input signal to the actual valve position, which is measured by a non-contact sensor.
• Actuation: Based on the comparison, the microprocessor sends a control signal to the torque motor/flapper nozzle mechanism. This mechanism then precisely controls the airflow to the pneumatic actuator.
  Valve positioning: The actuator moves the valve to the position that matches the input signal, closing the control loop.
• Feedback: The positioner can provide a feedback signal (e.g., 4-20mA or digital) back to the controller to indicate the actual valve position.
• Smart functions:

• PID control: The positioner uses a proportional-integral-derivative (PID) control algorithm to ensure stable and accurate operation.
• Auto-calibration: The device can automatically calibrate itself, which includes determining the zero position and travel range.
• HART communication: It supports the HART protocol for communication, allowing for remote configuration and diagnostics.

Core components and sequence of operation

The working principle of the YT-3303 involves a closed-loop control system with the following key steps:

1. Input signal and microprocessor: A process controller sends a 4–20 mA DC input signal to the YT-3303. The positioner's microprocessor receives and interprets this signal, which represents the desired valve position.
2. Conversion to pneumatic signal: The microprocessor controls a solenoid or a piezo-valve system to regulate the flow of compressed air. This system converts the electronic command into a variable air pressure signal.
3. Actuator movement: The variable air pressure is fed to the pneumatic valve actuator. This pressure causes the actuator to move the valve stem to the desired position.
4. Position feedback: A non-contact sensor inside the positioner continuously monitors the valve stem's actual position.
5. Digital feedback loop: The microprocessor compares the actual valve position (from the sensor) with the desired position (from the input signal). If there is a difference, it makes real-time adjustments to the pneumatic output to correct the valve's position.
6. HART communication: The YT-3303 also supports the HART communication protocol, which allows it to send back diagnostic and position feedback data digitally over the same 4–20 mA current loop.

Key functions enabled by its smart technology

The YT-3303's microprocessor enables several advanced features that improve performance and reliability compared to conventional positioners:

• Auto-calibration: With a push of a button, the positioner can automatically calibrate its zero and span points, simplifying the setup process.
• PID control: It uses built-in Proportional-Integral-Derivative (PID) control algorithms for fine-tuning the valve's response. This helps minimize overshoot and achieve quick, stable positioning.
• Low air consumption: The device is designed to be highly efficient, significantly reducing its air consumption when the valve is at a stable position.
• Selectable flow characteristics: The positioner can be configured with different flow characteristics (linear, equal percentage, quick open, or custom) to suit the specific application.
• Diagnostic capabilities: Through HART communication, it can provide advanced diagnostics and health monitoring, such as detecting wear, stiction, or air leakage. This supports a predictive maintenance strategy.
• Auto/Manual switch: An easy-to-use switch allows the operator to manually override the automated control for troubleshooting or maintenance.

 Full Datasheet

Positioner Transmitter Feature   YT-3303LSI2500L

Basic Ordering Information 

ROTORK /YCT  YT-3301  Series -  YT-3301LDI1221S1

The Rotork YT-3301 Smart Positioner works by receiving a \(4-20\) mA input signal from a controller and accurately controlling a valve's stroke to match that signal. A built-in microprocessor optimizes performance by enabling features like auto-calibration, PID control, and HART communication. The positioner uses a feedback mechanism to report the actual valve position and compares it to the command signal, making adjustments to minimize the difference. 

Working principle

• Input Signal: The device receives a standard \(4-20\) mA electrical signal from a control system, which represents the desired valve position.
• Microprocessor: A built-in microprocessor interprets the input signal and controls the pneumatic output to the actuator.
• Pneumatic Control: The positioner sends air pressure to the actuator to open or close the valve. It controls the amount of air pressure to achieve the exact position commanded by the input signal.
• Feedback Loop: A feedback sensor (either built-in or a separated module) measures the actual position of the valve stem or shaft.
• Correction: The microprocessor compares the actual position to the commanded position. If there is a discrepancy, it will adjust the air pressure to the actuator to correct the valve's position.
• Unique Functions: The microprocessor allows for advanced features, including:

• Auto-calibration: The unit automatically calibrates itself for optimal performance.
• PID control: The positioner can perform its own proportional-integral-derivative (PID) control to manage valve position and reduce hunting.
• HART communication: The positioner communicates with the control system using the HART protocol for digital data and control.`Alarms: It can trigger alarms based on various conditions.

• User Interface: It includes an LCD display and buttons for local control and configuration, as well as a switch for manual operation.

Core components and their functions

• Microprocessor: The "brain" of the device. It processes the input signal, receives feedback on the current valve position, and calculates the necessary adjustment.
• Input signal: An electrical signal, typically 4-20 mA DC, is sent from a control system (DCS, PLC, etc.) and represents the desired valve position.
• Supply pressure: A constant source of clean, dry air is connected to the positioner to provide the pneumatic power needed to move the valve actuator.
• Electro-pneumatic transducer (I/P): A solenoid or torque motor converts the variable electrical current from the microprocessor into a corresponding, variable pneumatic signal.
• Pneumatic relay/valve assembly: This component receives the pneumatic signal from the transducer and controls the flow of the main supply air to the actuator. It is responsible for amplifying the pneumatic signal to deliver the force required to move the actuator.
• Position sensor (remote): The YT-3301 is a remote-type positioner, meaning the sensor is separate from the main body. This sensor continuously monitors the physical position (stroke or rotation) of the valve stem.
• Feedback signal: The position sensor sends a 4-20 mA electrical signal back to the positioner's microprocessor, representing the valve's actual position.

The closed-loop control process

1. Desired position input: The positioner receives a 4-20 mA DC current signal from a control system, which tells it what position the valve is supposed to be in (e.g., 50% open).
2. Actual position measurement: The remote sensor continuously measures the actual physical position of the valve stem and sends a feedback signal (typically a 4-20 mA output) to the positioner's microprocessor.
3. Microprocessor comparison: The microprocessor compares the desired position from the input signal with the actual position reported by the sensor.
4. Error signal calculation: If there is a difference between the desired and actual positions, the microprocessor calculates an "error" signal. This is a core function of the built-in PID (Proportional-Integral-Derivative) control algorithm.
5. Pneumatic output adjustment: The microprocessor sends a new, precise control signal to the internal electro-pneumatic transducer.
6. Actuator movement: The pneumatic relay receives the signal from the transducer and rapidly adjusts the air pressure being supplied to the actuator's diaphragm or pistons. This moves the valve stem or shaft.
7. Correction and stabilization: The process repeats in real time. The microprocessor continues to monitor the actual position and adjust the pneumatic output until the actual position matches the desired position. This continuous feedback loop ensures high accuracy and stability.

Key features enhancing the working principle

• Auto-calibration: This function allows the positioner to automatically calibrate itself to the actuator's stroke range. The microprocessor maps the 4-20 mA signal to the physical travel limits, simplifying setup.
• HART communication: This protocol allows for digital communication over the analog 4-20 mA signal. Technicians can remotely configure settings, perform diagnostics, and get feedback from the positioner.
• Remote sensor (YT-3301): The YT-3301 model's remote sensor is designed to improve performance in harsh environments with high temperature or vibration by separating the sensitive electronics from the stress.
• Adjustable output characteristics: The positioner can be configured for different flow characteristics, such as linear, quick-opening, or equal percentage, to match specific application needs.

 Full Datasheet

Positioner Transmitter Feature   YT-3301LDI1221S1

Basic Ordering Information