Electronic Tripping Characteristics of Circuit breaker

Long-time Ampere Rating and Delay : This adjustable function simulates the effect of a bimetal conductor in a thermal-magnetic circuit breaker. It reacts to overload conditions and determines how much current the circuit breaker will carry continuously. The nominal pickup point where a circuit breaker trip unit detects an overload is at 1.075 times the selected ampere rating. After the circuit breaker has picked up, it will not trip until the delay determined by the long-time delay adjustment has

been achieved.

Short-time Pickup and Delay : The short-time function allows the circuit breaker to delay before tripping on high level over currents, resulting in maximum coordination. I²t IN—results in an inverse-time delay characteristic that most closely parallels time/current characteristics of fuses. I²t OUT—results in a constant delay characteristic that coordinates best with thermal-magnetic and electronic trip circuit breakers.

Instantaneous Pickup : The instantaneous pickup function simulates the magnetic characteristic of a

thermal-magnetic circuit breaker. This function trips the circuit breaker with no intentional time delay. In circuit breakers with both short-time and instantaneous pickup, the instantaneous pickup will override the short-time pickup if the instantaneous pickup is set at the same or lower setting than the short-time pickup.