ELECTRIC FUSE -A SAFETY DEVICE

 Taskeen Fathima S
1st Sem BCA, NCMS

The electric fuse is a device which is used to limit the current in an electric circuit. It safeguards the circuit and the appliances connected in the circuit from being damaged if the current in the circuit exceeds the specified value due to Voltage fluctuations are short circuiting. It consists of a fuse wire F which is stretched between the two metal terminal. The holder fits into a porcelain socket. The fuse wire is a short and thin piece of wire if a material of low melting point. Generally, the fuse wire is made up of an a alloy of led and thin, having 50% of each metal.

PURPOSE

If the insulation on the wire of cable used in wiring breaks, the live wire comes in a contact with the neutral wire which results in a short circuit. Maximum current then passes through the wires which can cause burning of the wires due to the excessive heat. Similarly, due to voltage fluctuations, sometimes high current flows through the wires that can cause burning of wires. To prevent this damage, a fuse is a connected to the live wire of the circuit. When there is a short circuit, the fuse wire gets heated up to the extent that it melts. As a result, a gap is produced in the live wire and the circuit becomes incomplete or breaks. No current then flows and the appliance or the circuit is saved. After removing the fault in the circuit or the appliance, a new fuse wire is fixed between the terminals in the holder to complete the circuit again.

CHARACTERISTICS

1. Fuse wire is connected in the series with the live wire it’s temperature rises much faster than the connecting copper wires when an excessive current flows because it’s resistance is higher than of the connecting copper wires.

2. The thickness of a fuse wire depends on the current rating of it. Higher the rating, thicker is the wire. It means that 15 A fuse is thicker than the 5 A fuse. The heating of fuse wire does not depend on its length.