Electrical Engineering XYZ MCQs
If the fault is very nearer to the generator, the fault current is:
- Larger
- Zero
- Less
- Any of the above
Correct answer: 1. Larger
Explanation: The correct answer is “Larger.”
When a fault occurs very close to the generator in an electrical power system, the fault current tends to be larger compared to faults occurring farther away. This is because the impedance between the generator and the fault location is typically lower when the fault is closer to the generator.
To explain further:
- Impedance: The impedance of the transmission lines and other components between the generator and the fault location contributes to the overall resistance and reactance of the circuit. When the fault is closer to the generator, there is less impedance for the fault current to overcome, leading to higher fault current.
- Voltage: The voltage at the fault location is also higher when the fault is closer to the generator, as there is less voltage drop along the transmission lines. Higher voltage results in higher current according to Ohm’s Law (I = V/R), assuming the impedance (R) remains relatively constant.
- Protection Coordination: Power system protection devices, such as circuit breakers and relays, are designed to detect and isolate faults. When a fault is very close to the generator, these protection devices may operate faster due to the higher fault current, minimizing potential damage to the system.
So, in summary, when a fault is very near to the generator, the fault current is larger due to lower impedance and higher voltage, making it easier for the fault current to flow.