Cascade control utilizes:

Cascade control is a control strategy used in various systems, including refrigeration, to improve the overall performance and response time by utilizing multiple control loops. In this context, it involves the use of two controllers where one controller (the primary controller) manages the setpoint for the second controller (the secondary controller). This setup allows for more precise control over variables by addressing disturbances in a more efficient manner.

The correct configuration for cascade control typically requires one transmitter to provide feedback for the primary controller and two valves. The primary controller will adjust the setpoint based on the measurements from the transmitter, while the secondary controller will manage the flow of the refrigerant or other fluid through the system via the two valves. This setup allows for better control over the process variables, enhancing stability and performance.

In this scenario, the use of one transmitter simplifies the measurement process while maintaining the effectiveness of the control strategy through the two actively controlled valves. This configuration is fundamental to achieving efficient operation in systems that require detailed control over multiple parameters.

Understanding this foundational aspect of cascade control helps in grasping its application in refrigeration and other industrial systems.