Proportional Control Action

This parameter generates a control action based on the current value of the error. In a more simplified sense, if the error is +2, the control action is -2. The proportional action can be generated by multiplying the error with a proportional constant- $K_p$. Mathematical representation of the same is given below,

$$P = K_p e(t)$$ (5.1)

where,
$P$ is the proportional output
$K_p$ is the proportional gain
$e(t)$ is the error signal

The value of $K_p$ is very important. A large value of $K_p$ may lead to instability of the system. In contrast, a smaller value of $K_P$ may decrease the controller's sensitivity towards error. The problem involved in using only proportional action is that the control action will never settle down to its target value and will always retain a steady-state error.