Miniature Circuit-breakers - MCB
(MCBs) to BS EN 60898 are suitable for operation by ordinary persons and have fixed protection settings, generally a two position on/off operating handle and a performance relative to the final circuits in an electrical installation.They would normally be the final overcurrent protection measure in the electrical system, for example before sockets or lighting circuits.
Warning: The content of this article is cited from Guide to Low Voltage Circuit-Breakers Standards - BEAMA!!!
Typical current ratings are from 0.5 A to 125 A. Short-circuit ratings may be up to 25 kA. Performance and testing is in accordance with BS EN 60898 for domestic and similar applications categorised by the trip characteristic types B, C & D. MCBs may also be available with application specific tripping characteristics.
MCBs may also be rated in accordance with BS EN 60947-2 for industrial or similar applications
Moulded Case Circuit-breakers - MCCB
(MCCBs) may have fixed or adjustable protection settings, normally a three position toggle operating handle giving on-off-tripped indication plus reset function, and a performance level relative to the incoming supply such that they can be installed at a point close to the supply transformer.
Typical current ratings are from 16 A to 1600 A though ratings up to 3,200 A are available. Short-circuit ratings may be up to 100 kA. Performance and testing is in accordance with BS EN 60947-2.
Air Circuit-breakers - ACB
(ACBs) are normally used as the main incoming protection and have a spring-operated mechanism to open and close the device often charged by an internal motor. The protection settings will include time delays and the devices will have a short-time withstand value to give full discrimination under fault conditions with downstream protection devices.
Typical current ratings are 630 to 6,300 A. Short-circuit ratings may be up to 150 kA. Performance and testing is in accordance with BS EN 60947-2.