When is the best time to interrupt fault current?

Interrupting fault current within the first quarter of a cycle is crucial for maintaining safety and system integrity. During a fault condition, such as a short circuit, the current can increase dramatically within a very short time frame. The first quarter of a cycle is particularly critical because this is when the fault current typically reaches its peak.

Quick interruption during this period helps to minimize damage to equipment and reduces the risk of fire hazards or injuries. Rapid interruption can also prevent further complications in the electrical system, such as cascading failures or additional faults that can occur following the initial fault.

Interrupting during peak hours or after detecting smoke would not provide the rapid response needed to protect infrastructure and personnel. Similarly, waiting for one full cycle allows the current to reach its maximum level, leading to more significant damage and hazards. Therefore, acting quickly, especially within that initial quarter cycle, is essential in fault situations.