Exam Question
(a) How protection is provided for electrical short circuit. (4)
(b) Describe the construction and operation of HRC fuses. (8)
(c) What are the advantages of HRC fuses (4)
Class 4 (4th Engineer)
MET
📅 Mar 2026
Reference Answer
### (a) Protection Against Electrical Short Circuit
A short circuit is a low-resistance path for current to flow, which bypasses the intended load. This results in an extremely high current, known as fault current, flowing from the source. This fault current can cause catastrophic damage through:
* **Thermal Effects**: Intense heat ($$P = I^2R$$) can melt insulation, damage conductors, and initiate fires.
* **Electrodynamic Forces**: Strong magnetic fields created by the high current can physically deform or destroy busbars, switchgear, and other components.
A short circuit is a low-resistance path for current to flow, which bypasses the intended load. This results in an extremely high current, known as fault current, flowing from the source. This fault current can cause catastrophic damage through:
* **Thermal Effects**: Intense heat ($$P = I^2R$$) can melt insulation, damage conductors, and initiate fires.
* **Electrodynamic Forces**: Strong magnetic fields created by the high current can physically deform or destroy busbars, switchgear, and other components.
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