The Lifetime of a Power Transformer

Lifetime of a Power Transformer

The Lifetime of a Power Transformer. Annual losses caused by power supply interruptions, reach into millions or even billions of dollars. The issue of power generation, transmission and distribution is of strategic importance.

One of the essential elements of the power grid is the transformer. Knowing the condition of a transformer and its estimated lifetime allows to efficiently manage the costs and minimize possible losses.

Transformer failures are caused by many factors, such as damaged windings, tank leaks, tap changer failures, contamination of insulation oil, high temperature and overloads etc. Hence the question: how can all factors be considered to extend transformer lifetime?

First, transformer type must be taken into consideration: whether the transformer is sealed or has a breather valve, if the transformer has nitrogen protection. Another important piece of information is the annual load cycle and operation temperatures. With this data, it is possible to estimate the annual lifetime impact using the method laid out in C57.91-2011 – IEEE Guide for Loading Mineral-Oil-Immersed Transformers and Step-Voltage Regulators standard. This is important to set the load limits for transformers of a certain class.

Regulatory documentation sets the average transformer lifetime duration. It varies from country to country, but in general stays around 25-30 years.