Which risk increases when a three-phase power transformer's tertiary winding unloaded is connected closing the grounding circuit intermittently?

💡 Explanation

When a tertiary winding circuit is opened and closed intermittently, Ferroresonance occurs causing high overvoltages because the transformer's non-linear magnetizing inductance resonates with the system capacitance as the air serves as dielctric when the circuit opens. Therefore, ferroresonant overvoltages increases, not saturation, losses, or current flow which require specific conditions not present.

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