Selectivity between overcurrent protective device (OCPD)
Frequently Asked Questions
What is OCPD selectivity?
Selectivity refers to the proper coordination between overcurrent protective devices so that only the affected device trips during a fault, leaving other parts of the system operational.
How is selectivity achieved between an upstream circuit breaker and a downstream fuse?
Selectivity is obtained by comparing time-current characteristics, maintaining a safety margin between the maximum tripping time of the fuse and the minimum tripping time of the circuit breaker. A delta time ≥1s is recommended for thermal-magnetic breakers and 100ms for electronic trip units.
What is Eprotek's SCB?
Eprotek's SCB is a surge protective device (SPD) overcurrent protective device that provides backup over-current protection for the SPD, fully coordinated with the SPD according to different models.
How does Eprotek's SCB compare to traditional backup circuit breakers or fuses?
Eprotek's SCB achieves a better balance between surge withstand performance (no tripping during expected surges) and sharp reaction against short circuit and abnormal leakage current.
Where can I find more technical details on selectivity?
For more detailed technical insights, always consult the OCPD manufacturer’s documentation.
