What device protects a fuse from a temporary fault?

The device that protects a fuse from a temporary fault is the oil circuit breaker. When a temporary fault occurs, such as a short circuit, an oil circuit breaker can quickly detect the increase in current and interrupt the circuit. This rapid action prevents excessive current from flowing through the fuse, thereby safeguarding it from melting or blowing unnecessarily.

An oil circuit breaker operates by using oil to insulate and cool the contacts during operation and interruption, which is crucial for maintaining system integrity and protecting equipment. When a fault is detected, the breaker opens the circuit, cutting off the current and allowing for the fault condition to be assessed and resolved without damaging the fuse.

In contrast, while a fuse link is designed to blow when a specific current level is exceeded, it does not inherently protect the circuit against temporary faults that may not cause sustained overcurrent conditions. Current transformers and relays serve different protective and monitoring functions in a power system but are not specifically designed to protect fuses from temporary faults in the same manner that an oil circuit breaker does.