Background of Arc Control

1.1 Background

In the low and medium voltage range, a circuit interrupting device is used to interrupt
prospective peak short circuit current up to 100,000 A. These devices must have the
ability not only to interrupt load currents, but also to interrupt a short circuit when the
fault current can reach a magnitude many times full load.
The fuse, by comparison with circuit breakers, suffers the disadvantage that
replacement is necessary after operation. The physical size of the fuse and therefore,
its cost, is directly proportional to its current rating. The fuse, being a thermal device,
generates more heat than the current carrying parts of a circuit breaker of equivalent
normal load.
The circuit breaker is of vital importance as a device used for making and breaking an
electrical circuit under conditions of varying severity. The functions are [1]:
• It must be capable of closing and carrying full load currents for long periods.
• Under prescribed conditions, it must open automatically to disconnect the load or
some small overload.
• It must successfully and rapidly interrupt the heavy currents, which flow when a
short circuit occurs.
• With its contacts open, the gap must withstand the circuit voltage.
• It must be capable of closing on to a circuit in which a fault exists and
immediately re-opening to clear a fault from the system

Reference: Arc Control in Circuit Breakers: Low Contact Velocity Paperback – 1 Jan 2017 by Dr Kesorn Pechrach PhD (Author)