As fuel costs rise and power outages become more frequent across the country, the power generation and distribution system in the US has become a focus of attention. So has the need to conserve energy and the need to invest in energy efficient products of all kinds. Of particular interest are products such as power transformers that remain energized and consume power 24 hours a day.
The transformer is a critical component of the energy network. If even a single unit is turned off for a short period of time, a large number of homes and business establishments are plunged into darkness, resulting in a substantial economic loss.
Unfortunately, a significant amount of equipment on the utility network is over 40 years old and must be replaced in the near future. According to the Department of Energy (DOE), distribution transformers that are 30 years old or older can waste between 60 and 80 billion kWh per year. A better designed transformer could generate annual energy savings of up to a billion dollars. Therefore, maintenance, upgrade and purchase of new transformers are fast becoming imperatives.
The importance of transformers
The distribution transformer: is the single most important piece of electrical equipment installed in an electrical distribution network. It also has a huge impact on the overall cost, efficiency, and reliability of a network. Select and purchase energy efficient distribution transformers optimized for:
* A particular distribution network
* The investment strategy of the utility company
* Network maintenance policies
* Local service and loading conditions.
– It will provide definite benefits (better financial and technical performance) for both the utilities and their clients.
As climate change looms on the horizon, so is interest in protecting the environment from greenhouse gas emissions. The regulatory requirement now is to install high-efficiency distribution transformers that have less power losses, eventually resulting in fewer pollutants being released into the environment.
Transmission losses
Transformers are not perfect devices; they do not convert 100% of the energy input into usable energy production. The difference between the energy input and that which is available at its output is quantified as energy loss. There are two types of transformer losses: no-load losses and no-load losses.
* No-load losses
No-load losses are also known as core losses. This loss is calculated based on the amount of energy required to magnetize the transformer core. Since most distribution transformers are energized 24/7, no-load losses are present at all times, whether a load is connected to the transformer or not. When lightly loaded, no-load losses account for the majority of total losses.
* Head losses
Load losses, on the other hand, are those incidental losses when transporting a load. These include winding losses, stray losses due to stray flux in core windings and clamps, and circulating currents in parallel windings. Because the load losses are a function of the square of the load current, they increase rapidly as the transformer loads. Head losses represent the largest part of total losses when a transformer is heavily loaded.
Deciding which transformer to buy
Many electrical distribution companies claim that they purchase distribution transformers through some type of loss assessment procedure. However, the cost of the transformer is still an important factor in determining which transformer to buy. A transformer’s components, design, construction, and installation affect its cost. For example, amorphous metal core transformers have 75% less no-load loss than a silicon steel core transformer, but cost 25% more than a silicon steel transformer.
Transformer losses affect the cost of design, construction, and installation. The transformer manufacturer generally incorporates the cost of losses into the cost of the transformer to optimize the transformer design.
Most companies that buy transformers look at the price rather than the total cost of ownership (TCO). The TCO over the life of the transformer tends to be high for the lower energy efficient transformers, while the initial cost is higher and the TCO low for the energy efficient transformers.
However, the payback period for high-efficiency transformers is relatively short, often less than 2 years. The Internal Rate of Return in energy efficient transformers is constantly above 10% and sometimes up to 70%.
Making purchasing decisions for a large power transformer is more complex than simply comparing manufacturer prices. It requires a company to know its requirements and compare not only the cost of transformers but also the TCO over a period of two to three decades. If this is done accurately, the cost-effective solution invariably turns out to be the energy efficient transformer, although it has a slightly higher initial cost.
When buying transformers, it is not a ‘short term’; These infrastructure investments are typically made with 30-50 years of service in mind. Therefore, energy efficient transformers are definitely the only way to go, given the strong economic case they represent in the long term.
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