Which protective action first occurs when transformer oil temperature exceeds alarm threshold?

💡 Explanation

When transformer oil temperature rises above the alarm threshold, the forced oil cooling system activates because increased cooling demand signals overheating, requiring supplemental heat removal. Therefore forced oil cooling activation results, rather than tap changer lockout, differential tripping, or pressure relay operation which require more severe fault conditions.

• Which outcome occurs when thermal runaway initiates in a transformer's oil-filled tank?
• Which risk increases in a prestressed concrete beam if the steel tendons experience hydrogen embrittlement?
• Which risk is most elevated when post-tensioned concrete tendons experience corrosion induced volume expansion within a bridge structure?
• Which risk increases when a three-phase circuit breaker fails to fully open one phase during a fault condition?
• Which consequence results when exceeding positional tolerances during jet engine turbine blade casting?
• Which failure causes concrete spalling due to rebar corrosion?