How long can a power transformer be stored?

Medium and large power transformers and reactors can typically be stored for up to 6 months following dismantling for transport after test. For longer storage periods, there is a risk of loss of liquid impregnation from the solid insulation which may adversely affect its dielectric strength.

Where do power transformers and reactors need to be stored?

Power transformers and reactors may need to be stored to accommodate constraints in manufacturing, transport, or installation. This storage may take place at the factory, the installation site, or alternative storage facilities. In some cases, transformers and...

Should a transformer be fully assembled during storage?

There are advantages to fully assembling the transformer or reactor during storage for a spare in long-term storage. Firstly, it preserves the condition of components which might otherwise become contaminated or deteriorate if stored separately, e.g., bushings and coolers.

Why are transformers switched on and off?

Transformers may be switched on and off for various reasons. While network transformers are seldom switched, generator transformers may be switched more frequently depending on dispatch requirements. Hence, transformer energisation or re-energisation is a normal planned operation in an electric power system.

Should a transformer be stored in a CIGRE manual?

CIGRE working group A2.34 gave some guidance on storage of spare components and materials, but not complete transformers (CIGRE brochure 445 2011 ). They also recommended that the operation and maintenance manual for transformers should include storage instructions.

Do Transformers store energy?

Separate primary and secondary windings facili-tate high voltage input/output isolation, especially important for safety in off-line applications. Ideally, a transformer stores no energy–all energy is transferred instantaneously from input to output. In practice, all transformers do store some undesired energy: