Reasons For Transformer Failures

As you are aware, the distribution sector has a large number of distribution transformers of several capacities. Any failure of these transformers is bound to cause great inconvenience to the consumers and huge financial losses to the utilities. It is thus very important to avoid transformer failure.        

We list below some significant reasons for distribution transformer failure.

•         Poor Performance

This could be because of

1          low oil level;

2          draining of oil due to leakage/theft of oil;

3          improper earthing;

4          frequent faults on LT lines due to loose spans leading to short circuit;

5          mechanical failure of winding;

6          improper tree clearance of LT lines;

7          defective breather and consequent ingress of moisture;

8          low electric strength of oil/winding insulation; and

9          corrosion of core laminations.

•          Improper Protection

This could be the result of

1          using defective or over rated fuses;

2          consistent overloading; and

3          not providing Lightning Arrestors (LAs).

•          Manufacturing Defects

These result from

1          improper / inadequate design;

2          poor quality of material;

3          bad workmanship; and

4          poor short circuits withstand capacity.

All these purpose for transformer failure can be classified under the subsequent heads (Figure):

a.) Ageing,

b.) Manufacturing defects,

c.) Improper structure/erection of distribution transformer,

d.) Improper operation and maintenance, and

e.) Natural calamities.

We now discuss each one of these briefly.