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The energy saving movement has been gaining traction over the past number of years and has really risen to prominence throughout the 21st Century. Whether in the news, politics, or business, energy efficiency is a topic on the tip of everybody’s tongue with global factors such as climate change receiving more attention than ever before.
As with any industry, transformer manufacturing has seen a wealth of changes throughout the years. Materials are now much more refined, tools and machinery are now quicker and more reliable than ever before, and customers are beginning to consider environmental implications when deciding on the transformer to meet their requirements.
This article will give an insight into the key components of a transformer that determine how efficiently it will run, the materials used to reduce energy losses, and how the rating and running temperature of a transformer influence its efficiency.
There are two main internal parts of a transformer that create energy losses - the core and the windings. The composition of these aspects of the transformer will determine how energy efficient it is. Core and winding losses combine to give the total watt loss of the core which determines the energy efficiency of the transformer.
The type of core present will depend on the size of the transformer. Transformers up to 150kVA will generally utilise laminated magnetic cores. This core type is comprised of thin sheets of electrical steel covered with an insulating layer. Larger transformers above 150kVA usually use silicon steel for core material. Silicon steel is a higher grade material and, subsequently, results in lower energy losses.
Eastern Transformers & Equipment (ETE) use a unique design of high grade steel cores for all transformers above 75kVA providing the transformers with good power to weight ratios and low watts loss. This low loss design of the core ensures a highly efficient transformer when compared to cut cores.
The conducting material used for the windings of a transformer will depend on its application, however the most commonly used metals are copper and aluminium. Copper is second only to silver in the most conductive elements table with aluminium in fourth behind gold. Both copper and aluminium have their benefits and are valid materials for use in transformer design.
The low resistance per unit length of copper allows for production of a transformer that runs cooler without unnecessarily increasing its required size. Aluminium possesses 61% of copper’s conductivity but can still perform to the same efficiency level when a greater amount of the material is utilised to compensate for this. A potential downside of this is that the manufacturer would need to keep a lot more winding material in stock and the final transformer would have a volume approximately 1.27 times that of its copper counterpart.
Space is often of a premium in control panels and enclosures and an unnecessarily large transformer might be off-putting to potential customers. Aluminium is the cheapest of the top four conductive metals and manufacturing a transformer using this as your winding material would be the most cost-effective method metre for metre. Moreover, aluminium is significantly lighter than copper weighing in at just 30% of copper’s net weight. Using aluminium makes for a much less cumbersome and easier to move transformer. The question that needs to be asked is whether the cost savings are worth the reduction in energy efficiency. Transformers using copper might have a higher initial cost, but the value for money will prove greater in the long run as transformers wound with copper will have few losses and, as such, greater efficiency.
ETE use copper for all manufactured transformers, unless there is a considerably high production requirement, as the company has always endeavoured to provide competitively priced transformers without compromising on the quality of the materials used.
Rating and running temperature
All electrical appliances emit waste heat as a by-product of their operation. Transformers are no exception. Generally, the lower a transformer’s temperature rise the more efficient it is.
Transformers are wound in line with EN temperature rise standards and are generally based on a maximum ambient temperature of 40°C with potential temperature rise depending on its intended environment and application. Transformers can run safely at temperatures as high as 180°C using Class H insulating materials and beyond using materials at Class C.
The higher the rating of a transformer the better its energy efficiency. This is clearly evident when comparing a 50VA transformer, for example, to a 500kVA transformer. A 50VA transformer will generally have an efficiency of around 70%, whereas a 500kVA unit can have efficiencies of 98% or higher.
Transformer efficiency in the modern day
Energy saving is a prominent topic of discussion in the modern day with a growing expectation that electrical products are designed to be as energy efficient as possible. As such, it is becoming increasingly common for customers to ask for the energy efficiency of a transformer when placing an order. Ensuring transformers are as energy efficient as they can be is the norm in the present day when designing and manufacturing. All aspects of transformers have developed over the years from the quality of the materials used to the aesthetics. The energy efficiency is a welcome addition to this list and will ensure reduced power wastage and increased cost savings for years to come.
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