The term three-term controller is used for PID control. The addition to file proportional mode of the integral mode removes file offset and gives a steady-state value the same as the input set value; the addition of the derivative mode enables a system to rise more rapidly to the steady-state value. PID control is used where rapid and large disturbances may occur, the derivative mode taking care of the rapid change and the integral mode the large offset resulting from the large disturbance. If a system has a small capacitance then derivative action may not be needed to speed up the response and so PI control might be adequate, a large capacitive system would need the derivative mode to speed up the response.