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Customer Success Story

Hitachi Energy supports Swedish utility to maintain its transformers

Aging Swedish transformers are having to cope with consistently increasing energy consumption, so it is now more important than ever to maintain and regularly check the condition of transformers and their components.


Many of todays´ transformers installed in the 1960s and 1970s are nearing the end of their typical 40 to 50 year life span. Maintenance is always more cost-effective than reacting to a failure – this is demonstrated by Hitachi Energy’s effort to help C4 Elnät AB, the electric utility within C4 Energi group, maintain its transformers.

Knowledge and expertise are needed to meet this challenge. Hitachi Energy's experienced and knowledgeable transformer service team assists utilities and industries with a range of service and maintenance interventions to remedy issues in a timely manner.

Customer Highlights

The Swedish utility C4 Energi, owned by the municipality of Kristianstad, has recognized the im-portance of preventive maintenance and has decided to review and increase its investment in the maintenance of transformers and other power equipment at its facilities. The company needed to assess the condition of a transformer before moving it.

“After an in-depth discussion, Hitachi Energy was able to offer the expertise we needed" says Jacob Färdig, project manager at C4 Energi, responsible for transformer maintenance. 

“I went out to measure the values on the transformer, and took an oil sample for dissolved gas and oil condition analysis. Our experts at the transformer diagnostics laboratory in Ludvika, ana-lyzed it. It turned out that the bushings had poor insulation values and the three high-voltage bushings therefore needed to be replaced," says Daniel Schönström, Service Engineer at Hitachi Energy.


The laboratory made an overall assessment of the transformer’s status, with results categorized into a color scale. 

  • Green: Good condition
  • Yellow: poor condition, to be fixed in the future
  • Red: urgent attention is needed

The overall assessment of this transformer showed “red” so it was taken out of service for re-pairs. “In the meantime, we had to run our backup transformer while we waited for new high-voltage components. Hitachi Energy was able to get the equipment very fast and fixed the trans-former, so after six weeks it was back in service. We are very grateful for the outstanding ser-vice," says Färdig.


Transformers require regular oil and gas analysis to assess the condition.  

Hitachi Energy offers maintenance services to secure long term reliable transformer operation – the longer a transformer performs, the more sustainable it becomes.

“It's like taking your car for an annual inspection. If you have a transformer that is more than 15 years old, you should have a gas test once a year and check oil condition every three years," says Patrik Larsson, Sales Manager for Transformer Services in Southern Sweden, at Hitachi Energy. ,"It's an easy way to keep track of your transformers and forms the basis for transformer maintenance as well as for financial planning for your transformer fleet. It's not necessarily the oldest transformer that needs to be replaced first." 

The cooperation between C4 Energi and Hitachi Energy continues with a condition assessment of an additional transformer and gas and oil analysis set to be carried out on all transformers.

“We appreciate the competence and service willingness of Hitachi Energy. Our goal is now to catch up with the maintenance, plan and complete actions in time," Färdig says.

“We are very pleased to be able to assist C4 Energi in its maintenance efforts and we value this close cooperation. We want to help industries and energy companies with their preventive maintenance, and we have both the expertise and the local presence within our organization, needed to do so," says Elin Johansson, Local Product Group Manager, Transformer Service at Hitachi Energy in Sweden.