FM Techie

Electricity plays a vital role in our daily lives. However, electrical faults such as overloads and short circuits can cause serious damage. To prevent this, a Miniature Circuit Breaker (MCB) is used. It is a safety device designed to protect electrical circuits from damage due to excess current. What is an MCB? An MCB is an automatic switch that trips and disconnects the circuit when excessive current flows through it. Unlike traditional fuses, an MCB does not need replacement after tripping. It can simply be reset, making it more convenient and reliable. Current Ratings of MCB MCBs are available in different current ratings. The common ratings include: 1, 2, 4, 6, 10, 16, 20, 25, 32, 63, and up to 125 Amperes. How Does an MCB Work? An MCB operates using two main principles: Thermal Operation (Overload Protection) A bimetallic strip inside the MCB bends when heated due to continuous overcurrent. This bending causes the contacts to separate, disconnecting the circuit and preventing ove...

Residual Current Device (RCD) Protection What is an RCD? A Residual Current Device (RCD) trips the circuit when it detects an earth fault current, providing an extremely effective form of shock protection. How RCDs Work The amount of current flowing through the phase (line) should return through neutral. An RCD continuously monitors the current flow and detects any mismatch between the current flowing through phase and neutral. If an imbalance is detected, the RCD trips the circuit within 30 milliseconds, preventing potential electric shock or fire hazards. Common RCD Ratings and Their Applications 30 mA (milliamps) – Maximum permissible for personal shock protection. 100 mA – Provides enhanced shock protection, though not as sensitive as 30 mA. 300 mA – Maximum permissible for fire protection. Why Use RCDs? Prevents electric shock by cutting off power within milliseconds. Limits fire risks caused by earth faults. Detects faults early, preventing damage to electrical installations. P...