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In an AC system, what is a differential fault? It is a large difference between:
  • A
    The speed between the CSDU and generator.
  • B
    The loads on different bus bars.
  • C
    The real and reactive loads.
  • D
    A generator and its busbar.

A differential fault exists when there is a difference between the generator output current and the bus bar input current, which suggests that there is an earth fault between the two.


The generator is essentially the powerhouse that creates electricity. This electricity is then channeled to a busbar, which acts like a central hub connecting different electrical circuits. Think of the busbar as a meeting point where electricity from the generator is distributed to various parts of a system.

When there's a big difference in the electrical characteristics (like current, voltage, or frequency) between the generator and the busbar, it's a sign that something might be wrong. This difference can indicate issues within the generator itself or in the wiring that connects it to the busbar.

A differential fault specifically refers to this significant mismatch. It's a critical issue because it can lead to malfunctions or damage in the electrical system. To detect these faults, a special device called a differential relay is used. This relay constantly monitors the balance between the generator and the busbar. When it detects a large discrepancy, it triggers protective measures to prevent further damage or system failure.

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