A fuse itself does not detect faults in a circuit. Its primary function is to protect the circuit by interrupting the flow of current when it exceeds a certain threshold, known as the rated current or current rating of the fuse. When a fault such as overcurrent occurs in the circuit, the fuse heats up and melts, thereby breaking the circuit and disconnecting the power supply. This action prevents damage to the circuit components and reduces the risk of fire or other hazards caused by excessive current flow.
Similarly to a fuse, a circuit breaker does not detect faults in a circuit on its own. Circuit breakers are designed to automatically open or “trip” when they detect an overcurrent condition or a short circuit in the electrical circuit. This action interrupts the flow of electricity and protects the circuit and connected devices from damage. Circuit breakers are equipped with internal mechanisms that sense abnormal current levels and trigger the tripping mechanism to disconnect the circuit.
When a fault occurs in a circuit protected by a fuse, the fuse operates by melting its element and breaking the circuit. This interruption stops the flow of current and prevents further damage to the circuit components or appliances connected to it. Once the fault is cleared or corrected, the fuse must be replaced with a new one of the correct rating to restore electrical continuity and ensure continued protection against overcurrent conditions.
Detecting a fuse failure involves visually inspecting the fuse to see if the fuse element inside has melted or if there are signs of damage. A blown fuse can often be identified by a visibly broken or melted wire inside the fuse body. Additionally, a continuity test using a multimeter can confirm whether the fuse is intact or if it has blown and needs replacement to restore electrical function and protection in the circuit.
The device specifically designed to detect faults in an electrical circuit is typically a residual current device (RCD) or ground fault circuit interrupter (GFCI). These devices monitor the balance of current between the live and neutral conductors in a circuit. If they detect a leakage of current, such as through a person or a fault to ground, they quickly trip and disconnect the power supply. RCDs and GFCIs are crucial for protecting against electrical shocks and ground faults that could otherwise pose significant safety hazards in both residential and industrial settings.