What describes a "proportional control" in a control loop?

Proportional control in a control loop operates by adjusting the output based on the magnitude of the error signal, which is the difference between the desired setpoint and the measured process variable. When the error signal increases, the controller output increases proportionally to the error. This relationship ensures that the output responds more vigorously to larger errors, helping to close the gap between the actual value and the desired setpoint.

In practice, this means that if the process variable is significantly below the setpoint, the controller will provide a strong output to drive the system back toward the goal. Conversely, if the process variable is close to the setpoint, the output will be smaller. This proportional response allows for efficient and effective regulation of the controlled process in many applications, keeping the system stable while minimizing steady-state error.

Understanding this concept is crucial for effectively implementing and troubleshooting control systems, as it highlights the importance of the error signal's role in adjusting the output.