The full form of MCCB is

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Moulded Case Circuit Breaker

Explanation: The MCCB stands for Moulded Case Circuit Breaker. It is a type of electrical protection device used to protect an electrical circuit from excessive current, which can cause overload or short circuits.

Working Principle: The MCCB uses a temperature-sensitive device (thermal element) for overload protection and an electromagnetic device (magnetic element) for instantaneous short-circuit protection. When current exceeds the rated threshold, the thermal bimetallic strip bends to trip the latch mechanism, or the magnetic solenoid pulls the plunger to disconnect the contact points instantly.

Key Formulas: $I_{trip} > I_{rated}$ — Condition for tripping during overload or fault; $P = VI \cos\phi$ — Power handled by the breaker contacts

Key Points: Used in low voltage power distribution systems (typically up to 1000V AC).; Offers adjustable trip settings for greater flexibility compared to MCBs.; Provides protection against overload, short circuits, and sometimes ground faults.; Constructed with a moulded plastic housing to insulate live parts.

Advantages: Adjustable trip current settings; High current rating capacity (up to 2500A); Robust construction for industrial environments

Disadvantages: Larger physical size than MCB; Higher initial cost; Maintenance requirements for high-amperage units

Applications: Industrial motor starting; Main power distribution panels; Generator protection

Additional Info: MCB stands for Miniature Circuit Breaker and is generally used for lower current ratings up to 125A.. The term 'Moulded Case' refers to the assembly of all internal components within a single moulded plastic housing.

Answer: C is correct — MCCB stands for Moulded Case Circuit Breaker, which is an industrial-grade protective device.

Exam Tip: Always remember that MCBs are for residential branch circuits, while MCCBs are for industrial feeders and heavy load distribution.

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