PREVIOUSLY ASKED IN:
WBPSC Miscellaneous Preliminary 2019
Answer
use of fuse
Explanation
The most crucial safety device used to protect domestic electrical circuits and appliances from short-circuiting or overloading is an electric fuse. A fuse consists of a piece of wire with a low melting point. When excessive current flows through the circuit, it generates excess heat, causing the fuse wire to melt and break the circuit. This prevents potential fires and damage to appliances.
Key Points
- > A standard electrical fuse wire is an alloy made of Lead (Pb - 75%) and Tin (Sn - 25%).
- > The crucial characteristics of a fuse wire are its low melting point and high resistance.
- > The fuse is always connected in 'series' with the live wire of the circuit.
- > Earthing is done to protect the user from fatal electric shocks due to leakage current.
- > Modern households increasingly use MCB (Miniature Circuit Breaker) instead of traditional fuses.
Additional Information
Electrical Safety Devices & Functions
| Device | Primary Purpose | Working Principle |
|---|---|---|
| Fuse | Protection against overloading | Heating effect of electric current |
| Earthing | Protection against electric shock | Grounding excess leakage charge |
| Stabilizer | Maintaining steady voltage | Transformer principles |
| MCB | Modern replacement for fuses | Electromagnetic induction |
Memory Tips
- Fuse: Its job is to literally 'fuse' or melt down to sacrifice itself and break the connection, saving costly appliances.
- Short Circuit: Happens when the live and neutral wires come into direct contact, bypassing the normal load.