Fuse and MCB
Simple guide to understand electrical protection devices
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Click on either "Show Fuse" or "Show MCB" button above
Electrical Fuse
One-time circuit protection device
What is a Fuse?
A fuse is a simple safety device that protects electrical circuits by breaking when too much current flows.
It contains a thin metal wire that melts when overloaded, stopping electricity flow.
How It Works
- Electricity flows through fuse wire
- Too much current heats the wire
- Wire melts at designed temperature
- Circuit breaks, stopping electricity
- Fuse is destroyed - must be replaced
Advantages
- Simple and cheap
- Very fast response
- No maintenance needed
- Highly reliable
Disadvantages
- One-time use only
- Must be replaced after blowing
- No visual indication
- Cannot be used as switch
Miniature Circuit Breaker (MCB)
Reusable circuit protection device
What is an MCB?
An MCB is an automatic switch that protects circuits by turning off when it detects too much current.
Unlike a fuse, it can be reset and used again after tripping.
How It Works
- Switch is ON during normal operation
- Bimetallic strip heats on overload
- Strip bends, releasing trip mechanism
- Switch moves to OFF position
- Can be reset after fixing problem
Advantages
- Reusable - can be reset
- Clear ON/OFF indication
- Can be used as manual switch
- More convenient long-term
Disadvantages
- More expensive initially
- Slightly slower than fuse
- More complex mechanism
- Can be overridden