What is the recommended insulation resistance value for a 15kV liquid filled transformer?

The recommended insulation resistance value for a 15kV liquid-filled transformer is generally set at 5000 Megohms. This value is significant because it ensures that the insulation can effectively protect against electrical breakdown and failures. Insulation resistance is a critical parameter, as it indicates the condition of the insulation system; a high resistance value typically suggests that the insulation is in good health and capable of withstanding the operational voltage without allowing excessive leakage currents.

Set at 5000 Megohms for this voltage class, this recommendation helps safeguard the transformer from overheating, insulation damage, and potential operational failures, which can lead to costly downtimes and repairs. Adhering to this standard enhances the reliability and safety of the electrical equipment, ensuring it operates efficiently within its designed parameters.

The other values presented, while higher, exceed the established recommendation and may not necessarily provide additional benefit in practice. Each insulation value serves its purpose in different contexts, but for a 15kV liquid-filled transformer, 5000 Megohms strikes the appropriate balance between safety, operational integrity, and practical implementation.