There is a PRD on the DCS of the newly installed unit
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This post was last edited by sxf1028102800 on 2018-11-8 at 17:51. There is a PRD displayed on the device screen; it’s my first time encountering this, and I’m not quite sure what PRD primary regulators and secondary regulators are. For example, if I want to control the liquid level in a tank using flow control and by employing PRD, which one is the primary regulator and which one is the secondary regulator? Is it the same as CAS?
PRD or PID? CAS or SIS?
Manual (MAN), Automatic (AUT), Cascade (CAS), PRD mode. Manual adjustment directly outputs the MV value. Automatic regulation controls the MV output by adjusting the setpoint (SV). In cascade control, it is the MV value of the main loop, which is the setpoint (SV) value of the secondary loop. The PRD method involves directly outputting the MV value of the main circuit to the MV value of the secondary circuit.:L Baidu’s
All secondary loops with cascade control points have a PRD mode; in this mode, when there is a problem with the secondary loop controller or transmitter, the MV from the main loop can be directly sent to the MV of the secondary loop
Manual (MAN: Manual) mode, Automatic (AUT: Automation) mode, Cascade (CAS: Cascade) mode, Primary direct (PRD: Primary direct). In manual mode (MAN: Manual), the controller output is determined by the manual output value ； In automatic (AUT: Automation) mode, the controller output is determined by a value calculated from the deviation using a PID algorithm ； In the cascade (CAS) mode, the output of the main controller serves as a setpoint for the secondary controller, which is then fed to the secondary controller ； In the primary control (PRD: Primary direct) mode, the main controller takes over from the secondary controller to generate the output, which is sent directly to the actuator; at this time, the secondary controller is in a suspended state.