Does a blown fuse mean cutting off the power supply?

Yes, the melting of a fuse is essentially to cut off the power supply. But it has a more precise meaning and scope:

1. Cut off a specific circuit: When a fuse blows, it disconnects (cuts off) the current path of the circuit it protects.
2. Does not mean cutting off the main power supply: It does not mean cutting off the main power supply of the entire system (such as your home's main switch). The power supply upstream of the fuse (distribution panel, main switch) is usually still energized.
3. Melting is the result, cutting is the purpose:
Fuse: It describes the physical phenomenon of the metal conductor inside a fuse melting and breaking due to the heat generated by overcurrent (overload or short circuit).
Cut off power: describes the result of the physical phenomenon of melting - the circuit loses its power supply capability and the current is interrupted.

Summary of key points:

Protective function: The melting of a fuse is a manifestation of its core protective function. It forcibly cuts off the current by "self destruct" to prevent excessive current from damaging wires, equipment, or causing fires.
Partial cut-off: It cuts off the part of the circuit (branch circuit) that it is responsible for protecting, rather than the total power supply of the entire system.
Fault indication: A blown fuse usually indicates an overload or short circuit fault in the circuit. Before replacing the fuse, it is necessary to investigate and solve the cause of the fault, otherwise the new fuse will melt again.

Therefore, a more accurate statement would be:

>A blown fuse will cut off the power supply to the circuit it protects.

Important safety reminder:

Even if a fuse is blown, its two ends (incoming and outgoing) and the interior of the fuse holder may still be charged (from the upstream power source). When repairing or replacing fuses, it is necessary to ensure that the main switch or power switch of the circuit is disconnected, and use a voltage tester to confirm that there is no power before operation to prevent electric shock.
A blown fuse is a signal that there is a problem with the circuit. Blindly replacing a larger capacity fuse or using other conductors (such as copper wire) instead is a very dangerous behavior, which may cause the wire to overheat and catch fire.

In short, a blown fuse does indeed serve to cut off the power supply of the circuit it is in, which is the core purpose of its design. But it doesn't mean cutting off the overall power supply of the entire system.