Transformer Life Management Systems


Tasks & Targets


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Georg Daemisch



Transformer Life Management Systems

The Proceeding

a | The first step must be a reliable data collection of all transformers of a certain population, using classical means like oil sampling, DGA (Dissolved Gas Analysis and/or using On-line measurement and monitoring as modern alternative in order to get more reliable datas.

b | The second step is a diagnosis based on this data with the target to give decision bases for further evaluation, whether a certain transformer has to replaced in short time or which means has to be taken to keep him for limited or even unlimited time in service.

c | The third step is the formulation of a Life Management Plan (LMP) for that population, which defines the necessary treatments, reinvestment cycle, the investment in treatment systems and the optimized application of that equipment in order to cope with the requirements of safety, reliable service and economical optimization

The Solution

here are developed in the last 15 years a series of adequate tools and there are in developing stage already more tools and systems to cover the requirements listed under Item3, which allow to collect reliable data, avoiding apart of certain systematical errors the human factor especially. Tools for clear diagnosis give an easy understandable picture and basis for decision of further action.

The Action

Depending of the informations´ gained from the collected data it must be decided to apply drying, filtering, gas conditioning, sealing, oil regeneration. For the listed tasks are now the necessary ON-Line and OFF-line techniques available, in order to deal with the increasing severe situation. The whole process must be supported by a steady consulting service.


An industrial complex has 34 transformers up to 150 MVA in use. Due to overageing and not permitted technical data 2/3 of these population should be replaced. This means an Investment of 15 Mio Euros. Instead of this and as emergency measures in order to keep the technical limits, a sum of 0.5 Mio Euros were invested for recovering the technical limits and for conserving. Calculating with an interest rate of 10% for every year of delayed investment an advantage of 1,5 Mio can be gained. Or in other words the 0.5 Mio are repaid in 0.3 years. In fact at time being it will be assumed that the delay of reinvestment will be in average 5 years. Up to now the complete sum is delayed 3 years, which means that a profit in interest advantage of 4 Mio Euros can be calculated.


A not defined use of overaged transformers, that means outside of the commonly agreed limits must be regarded as a in no way calculable (and acceptable) technical risk, but nevertheless, even a risk to be persecuted by the courts. On the other hand allow the nowadays available hard- and software solutions to cope with that. These solutions permit a defined keeping in service or at least a secured controlled service till shut down. The necessary investment will be typically repaid in less than 12 month. .

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