Correct Answer - Option 3 : short circuit
Short Circuit:
- A short circuit is an electrical circuit that allows a current to travel along an unintended path with no or very low electrical impedance. This results in an excessive current flowing through the circuit.
- A short circuit fault can, within milliseconds, becomes a thousand times larger than the normal operating current of the system.
- Damage from the short circuits can be reduced or prevented by employing fuses, circuit breakers, or other overload protection, which disconnects the power in reaction to excessive current.
- Overload protection must be chosen according to the current rating of the circuit.
- During a short circuit, the current becomes large enough to produce excessive heat which can damage the conductor.
- Current (short circuit excessive current) being equal in all four conductors (Aluminum, copper, steel, ACSR) diverge the attention to the resistance of these conductors for the generation of heat during a short circuit.
- Aluminum has the highest resistance among them all, thus it would produce maximum heat during the short circuit. Also melting point of aluminum is least among them all, thus become of maximum heat generated, it could melt easily and can cause maximum damage when subjected to short circuits.
Note:
Heat generated = I2 Rt
Where I = Current (short circuit current)
R = Resistance of the conductor
t = time (in sec)
Solution:
When two phase wires or one phase wire and the neutral wire make direct contact due to insulation breakdown, an exceedingly large current will flow in the circuit. This condition is
called Short Circuit.
