Difference between MCB and OLR

MCB (Miniature Circuit Breaker):

An MCB is an automatically operated electrical switch designed to protect electrical circuits from damage caused by overload or short circuits. It is commonly used in residential, commercial, and industrial applications to ensure safety and prevent electrical fires.  

OLR (Overload Relay):

An OLR is a protective device used in motor control circuits to safeguard motors from overheating due to excessive current over time. It operates by disconnecting the power supply when it detects a sustained overload, preventing motor damage.

1. Function: MCB (Miniature Circuit Breaker) protects against overload and short circuits, while OLR (Overload Relay) specifically protects against motor overloads and single phasing.

2. Application: MCBs are used in general electrical circuits, whereas OLRs are primarily used in motor control circuits.

3. Operation: MCB trips instantly during a fault, while OLR operates with a time delay to allow for temporary motor overloads.

4. Reset: MCBs can be manually reset after tripping, while OLRs often require manual or automatic reset depending on the design.

5. Sensitivity: MCBs are sensitive to both current and temperature, while OLRs are mainly sensitive to current over a prolonged period.