The average age of transformers in use worldwide is now around 40 years. In Europe and the US, where most of the power grids were built in the 1960s and 1970s, they are often even older. Replacing these old transformers with new ones is not only expensive, but also impossible in the short term due to the current very long delivery times. More and more operators are therefore asking themselves how they can continue to use their aging equipment safely and efficiently.
Transformers on the limit: How a digital retrofit extends service life
Worldwide, transformers are getting older and older and have to perform better than ever before. How long can this continue? With a digital upgrade from MR, operators can better control and monitor their equipment and even extend its service life.
Transformers on the limit: How a digital retrofit extends service life
Worldwide, transformers are getting older and older and have to perform better than ever before. How long can this continue? With a digital upgrade from MR, operators can better control and monitor their equipment and even extend its service life.
Can digitalization help to ensure the operation of old transformers? To answer this question, it is important to understand what causes a transformer to age. There are many factors responsible for the aging process. However, thermal stress is a decisive factor in determining service life. It depends on the operating conditions, but also on external influences such as lightning strikes. Excessively high temperatures accelerate the aging of the insulating paper in the windings and also trigger complex decomposition processes in the insulating oil. This produces acids and gases, which in turn accelerate aging processes by oxidizing contacts, for example. It's a vicious circle.
Full control over transformer cooling
Precise temperature control is therefore a key factor in extending the service life of a transformer. This is becoming increasingly important as transformers undergo ever greater stress due to the integration of wind and solar power into the grids. Christian Hofmeister, Project Manager Service Solutions at MR, explains: “In substations connecting medium and low voltage, transformers were only operating at 20 to 30 percent capacity for decades, but today they are exposed to loads they have never experienced before in their entire service life.”
„Optimal utilization of the transformer is only possible if sufficient data about the condition of the transformer is available.“
Intelligent temperature management is therefore more important than ever. Old systems relied on simple bimetal thermostats to control cooling – these are tried and tested, but inaccurate. With more sophisticated sensors and software, the temperature in the windings can be determined and regulated much more accurately. And intelligent control systems cool transformers proactively, i.e. when high loads are expected. The result: the windings age more slowly and the risk of chemical decomposition in the insulating oil is reduced. And better temperature control also allows operations to be optimized and short-term overloads to be permitted in order to better control the grid. “However, intelligent control of the cooling system and optimal utilization of the transformer are only possible if sufficient data on the condition of the transformer is available,” explains Hofmeister.
ETOS® – the automation solution for power transformers
With ETOS® – an open automation solution for power transformers – and a broad portfolio of sensors for recording relevant operating data at critical points in the transformer, MR offers a comprehensive system for intelligent real-time monitoring and control of central components such as the cooling system. The ETOS® system has a modular design and is engineered for easy retrofitting. Hofmeister explains: “It is important to us that the customer gets exactly the functions he needs. Depending on the load, the demands on the system can vary, which is why we design each ETOS® system individually.”
Retrofit project: at the Substation in Meuselwitz MITNETZ STROM equipped two transformers with intelligent sensors before the ETOS® control cabinets were installed.
The MR team prepared every step of the retrofit in advance.
Two intelligent ETOS® control cabinets replace the old motor drives.
Ready for the future: it took just five days to set up and commission the ETOS® control cabinets.
Satisfied customer: Jan Schönfeld, Asset Manager at MITZNETZ STROM (right) and Christian Hofmeister, from MR.
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Example: MITNETZ STROM
MITNETZ STROM, the largest distribution network operator in eastern Germany, opted for such a retrofit and equipped two power transformers in the Meuselwitz substation with the ETOS® system. The retrofit included intelligent sensors, precise temperature management, vibroacoustic monitoring of the tap-changer, and an electronic dehydrating breather. The retrofit work by MR technicians took only five days. In view of the increasing demands posed by renewable energies and electromobility, this digitization solution offers a cost-efficient alternative to replacing old transformers. This is also confirmed by Jan Schönfeld, Asset Manager at MITNETZ STROM: “Retrofitting with electronics and sensor technology is significantly less costly than dismantling, removing, and installing a new transformer.”
„Retrofitting with electronics and sensors is significantly less costly than dismantling, removing, and installing a new transformer.“
From time-based to condition-based maintenance
Digitalization not only makes it possible to optimize transformer operation and thus slow down the aging process. Hofmeister explains: “Digitization and the availability of large amounts of data make it possible to switch from time-based periodic maintenance to a condition-based maintenance strategy.” Instead of rigid maintenance intervals, the transformer is maintained based on real condition data. By continuously recording relevant operating parameters – such as temperature, humidity, or gas formation in the oil – and combining this with intelligent analytics, operators can not only prevent damage, but also reduce maintenance costs and significantly extend the service life of their transformers.
Three steps to the digital transformer
With its ETOS® automation solution, combined with a wide range of sensors and protective devices, MR offers a modular system that can be used to retrofit transformers at any time. The retrofits are carried out by certified and specially trained service technicians.
Step 1: Inventory
An MR expert conducts an on-site inspection to assess the condition of the equipment, records existing transformer data, and takes measurements as necessary. Alternatively, the expert can be guided virtually through the substation via smartphone or tablet—the inventory is then carried out remotely.
Step 2: Configuration & planning
In the next step, MR experts develop a digitalization package tailored to the customer's requirements. The retrofit work is also planned meticulously to ensure that everything runs smoothly on site within the required time frame.
Step 3: Implementation of the retrofit
On the agreed date, MR service technicians bring all components, materials, and tools required for the retrofit. The operator only needs to disconnect the transformer from the power supply so that the work can be carried out. Once the retrofit is complete, operation can resume.
