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In: Electrical Engineering

Generally, a single-phase power is commonly found in domestic households, whereas a three-phase power is preferable...

Generally, a single-phase power is commonly found in domestic households, whereas a three-phase power is preferable for larger demands. For safety purpose, over-current protection components are compulsory in the electrical distribution systems.


i. Explain two advantages of a three-phase system compared to a single-phase system in the distribution system.

ii. Briefly describe the characteristic and the function of two types over-current protection device installed in the distribution board (DB) residential building.

iii. Miniature circuit breakers (MCB) with different current rating can be used to protect the individual sub-circuit. State the current rating of the MCB that typically used for:
• lighting,
• socket outlet (radial type),
• socket outlet (ring type) and
• air-conditioner circuits.

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