Protective relays are tuned to notice abnormal electrical conditions and trip breakers to isolate faults before damage spreads. The faults they most readily recognize are short circuits and ground faults because these produce abrupt, large changes in current and voltage that relays can detect quickly. A short circuit between conductors creates a very high current, while a ground fault causes current to flow to earth, upsetting current balance and voltage patterns. In both cases the protective circuits trip to protect equipment and maintain system stability. The other issues listed aren’t electrical faults that relays primarily identify. Damaged poles are a structural problem, and while they can lead to electrical faults, relays measure electrical signals rather than physical conditions. Defective hardware or broken strands relate to equipment condition and failure modes, not the immediate electrical signature the protection system is designed to sense.

Voltage scales with the turns ratio in an ideal transformer. The secondary voltage equals the primary voltage multiplied by the turns ratio (Ns/Np). For this transformer, the ratio is 4160/2400 ≈ 1.733. So applying 2400 V to the primary yields about 4160 V on the secondary. In real operation, small losses and regulation can cause minor differences, but the nominal secondary voltage follows the turns ratio.

Transmission lines can be installed either overhead on towers or buried as underground cables. The choice depends on factors like cost, right-of-way, reliability, and environmental or urban constraints. Overhead lines are common because they’re cheaper to install and easier to repair, but they need space, can be affected by weather, and are visually intrusive. Underground lines avoid weather exposure and reduce visual impact, but cost more and are harder to install and fault-find. Since both methods are used in practice, the true statement is that transmission lines can be overhead or underground. The other options—always overhead, always underground, or cannot be buried—aren’t accurate.

Power unit scales: giga- and mega- prefixes determine how many watts are in a gigawatt or a megawatt. Giga- means 10^9 and mega- means 10^6, so 1 gigawatt equals 10^9 watts and 1 megawatt equals 10^6 watts. Dividing gives 10^9 / 10^6 = 10^3, which is 1,000. So 1 gigawatt equals 1,000 megawatts. In practical terms, that means 100 MW is 0.1 GW, 10 MW is 0.01 GW, and 10,000 MW is 10 GW.