Improper Operation and Maintenance (O&M)
Transformer failure could also stem from poor O&M practices. For example, in addition to general full load, continuous over-heating and higher no-load losses might decrease the life of the transformer because of reduction in the life of insulating papers, oil, etc. Other improper O&M practices leading to transformer failure are discussed later here on enhancing transformer life and efficiency. In Table 3, we summaries some purpose for transformer failure.
Table 3: Failure of Distribution Transformers
Reason for
DTR Failure
|
Failure Rate
|
Causes
|
Damage to
LV Coils
|
65 %
|
• Compressed windings;
• Open Circuit Insulation failure;
• Dislodged spacers; and
• Broken support/inadequate bolts.
|
Damage to
HV Coils
|
5 %
|
• Overloading;
• Defective termination of coils; and
• Inadequate size of fuses.
|
Damage to
Both
|
10 %
|
• Any of the above causes.
|
Other
Reasons
|
20 %
|
• Poor construction of transformer tank;
• Defective Joints;
• Oil oozing out;
• Punctured radiators and bushing gaskets;
• Damaged tap changers, etc.
|
Therefore far, you have studied about the selection criteria of transformers, their placement and the purpose for transformer failure. If you are able to avoid these causes of transformer failures, the battle is more than half won. The rest is taken care of through transformer testing prior to its installation.