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NETWORK / 29 / DECEMBER 2016/JANUARY 2017 during their service life. There is an ageing process internally which does increase the likelihood of failures during normal and extreme operational situations. Failure does happen. There have been five emergency projects in the past month that have failed for different companies that Siemens Transformers has been involved in the replacement of. These haven't been linked to resilience, but like-for-like replacements where utility companies have an asset management programme where they have spares and we have gone in and repaired or replaced them. From our experience gained from being a partner of utilities worldwide for more than 100 years, Siemens Transformers knows about the state of the grid in a lot of regions. To address concerns of the perceived increase of risk of transformer outages, we have created a modular three- step concept called Pretact. The first layer to reduce risks to the existing transformer fleet is called PREVENT. This includes several service modules, like condition monitoring, repairs and retrofit to prevent unplanned outages due to failures in operation. This usually gives the utility companies some breathing space to think about what it is they are going to do about that problem asset. Whether to put in some other form of flexibility in the network to reduce the stress on that particular unit. The second layer consists of features to PROTECT the transformer from external risks. This may be extreme weather events like sun storms and thunderstorms, but also human impacts like vandalism. Some of these features can be retrofitted, others need to be considered already when ordering a new unit. How much does the risk of failure increase due to bad weather? Transformers are quite robust machines, so it really takes extreme weather events to threaten their operation. However, the likelihood of extreme weather has risen during the past decade. In the UK we can have as much of an issue with wet weather in September as we do with snow in February. In addition, we need to look at the complete system and not only the transformer: if there is a failure in another crucial component this might lead to a transformer failure. Looking at the recent past, thunderstorms and floods were the most common weather events that led to large blackouts. But, as mentioned before, not only weather is a threat to transformer operation. Events like earthquakes and vandalism unfortunately may have tremendous effects as well. And, as always, the most spectacular risks are feared most, but the majority of transformer failures happen simply during operation because of the aged transformer fleet. Siemens has created a solution that will cut replacement times in the event that assets do fail, how did this solution come into being? Yes, if all precautions that utilities can take fail, Siemens Transformers has come up with an innovative transformer type called Mobile Resilience Units. It enables transformer operators to REACT quickly if the worst case scenario is inevitable. The Mobile Resilience Units can be transported quickly to any location needed, because their single-phase design makes them compact and lightweight. The installation time is reduced dramatically, by up to 75%, because the units are equipped with plug-in-bushings and connections. This means the mobile resilience units enable transformer operators to restore their system within a few days rather than a period of weeks if a conventional power transformer was used. And, to top these advantages, Mobile Resilience Units are built to fit different voltage levels. This means the transformer operator does not need to invest in several different units, but can backup different strategic nodes in the network with just one set of mobile Resilience Units. Siemens is hugely into innovation. We pride ourselves on innovation, we feel like we are market leaders on innovation in the transformer business, but we don't do that on our own. A significant part of our job is to listen to the concerns of our customers and find ways to address them to make their life easier. Our transformer resilience concept was incubated with a customer. It wasn't just a product that we thought about and then just took it to market, it was actually generated with a customer in mind. We have taken that forward and invented a lot of features, which we have added to the product to protect against potential threats such as vandalism, sun storms and geomagnetic storms – both of which can cause problems with transformers. We are seeing massive amounts of embedded generation now, and despite all the positives, they do affect the grid in a negative way in regard to DC stress. That can cause prob- lems to transformers, so we have looked at it and designed them internally in a way that addresses the problem. What's next in the evolutionary journey for transformers? Environmental factors have become one of the big drivers for Siemens. There are a lot of environmental challenges when you are using a transformer that is full of mineral oil, and we have worked hard to address this in the past year or two. Only earlier this year we manufactured the first transformer at 400KV for a project at Hybury substation with National Grid that is filled with an ester-based product that is environmentally friendly. An additional benefit is this oil also has a higher flash point and doesn't burn as easily. This means that if there was a problem and a substation issue, the risk of explosion and fire is greatly diminished, while you are also tackling a huge environmental concern of the utility. It enhances the transformer's life, it prolongs it, but it also allows you to operate it at a higher temperature, which enhances its performance as well. Our Mobile Resilience Units also use this oil. They can be filled with standard mineral oil if a customer chooses, but our preferred option is to fill it with this ester- based fluid. N THe PreTacT coNcePT PreVeNT – reduces risks to the exist- ing transformer fleet ProTecT – transformers from external risks such as extreme weather and vandalism reacT – quickly if the worst-case scenario happens by replac- ing failed transformers with compact and lightweight Mobile Resilience Units

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