Proportional action lets the user affect the response time of the process. The higher the gain, the faster the response time, the lower the static error (in purely proportional terms), but the more the stability is reduced. Integral action is used to cancel the static error (difference between the measurement and setpoint values). The higher the integral action (Ti reduced), the faster the response and the lower the stability. Derivative action anticipates process response. It adds a term to the equation which takes into account the speed of error variation. This is used to anticipate by accelerating the response of the process when the error increases and slowing the response when the error diminishes. The higher the derivative action (Td high),the faster the response.