Circuit Breaker: Construction, Working, Types & Uses

MCB (Miniature Circuit Breaker), Construction, Working, Types & Uses
MCBs are used primarily as an alternative to the fuse switch in most of the circuits.
A wide variety of MCBs have been in use nowadays in all areas of domestic, commercial and industrial applications as a reliable means of protection.

Air Circuit Breaker (ACB) – Construction, Operation, Types and Uses
Circuit breakers are widely used in industries as well as power system for controlling and protection of different parts of the circuit like switch gears, Transformers, Motors, Generators/Alternator etc., which leads the system stable and reliable


  1. Ann Moody says:

    A circuit breaker, designed to protect an electrical circuit, is an automatically operated electrical switch.

    Portable Generators

  2. Tomi Engdahl says:

    E-fuses: warming up to higher-current applications

    The brief note explained the ins and outs of e-fuses with respect to these regulations, and it also reminded me of a point that it’s easy to overlook: fuses protect against overcurrent situations and the risk they pose to systems and people. They are not for high-voltage protection, even though we may unconsciously associate “danger” with AC-line voltage of 120/240V and the large amounts of current AC lines can deliver. The TI note lists approved e-fuses that go up to 4.5 to 60V at 6 A – clearly not line voltage, but still a substantial amount of current and double-digit voltage. Protection against high-voltage events is not a task for a fuse; instead, that is the role of MOVs, spark gaps, and other components.

  3. Tomi Engdahl says:
    For industrial LV installations the relevant IEC standards are, or are due to be:

    60947-1: general rules
    60947-2: part 2: circuit-breakers
    60947-3: part 3: switches, disconnectors, switch-disconnectors and fuse combination units
    60947-4: part 4: contactors and motor starters
    60947-5: part 5: control-circuit devices and switching elements
    60947-6: part 6: multiple function switching devices
    60947-7: part 7: ancillary equipment
    60947-8: Part 8: Control units for built-in thermal protection (PTC) for rotating electrical machines.

    IEC 60947-2:2016+AMD1:2019 CSV
    Consolidated version
    Low-voltage switchgear and controlgear – Part 2: Circuit-breakers

  4. Tomi Engdahl says:

    Failed elevator switch fuse / fusible disconnect

    This is a common industrial grade switch-fuse unit used for isolation and protection. The unit in this video had failed, so I thought it would be interesting to see what had gone wrong.


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