The Inefficient transformer

04 Oct The Inefficient transformer

Inefficient HV/LV transformer on site?


Transformer losses can account for up to 5% of the overall cost in loss of energy simply leaking away through inefficient transformation.

I hear you say,Tap our Transformers down and save money, job done simple?

Not So, We call it Tap Dancing, looks good , feels good, but look in the reality mirror , it will not work the way you think it might.


Tap Dancing – Energy Saving or Not


Well I guess if you are considering tapping down your site transformers it’s because you are suffering site Over-Voltage, a phenomenon that costs UK business millions of pounds each year. Typically, HV transformers can be adjusted to allow it to supply voltage slightly higher or lower than its normal output.

These tap settings are normally -5%, -2.5%, +2.5%, +5%.

As the physics of voltage reduction, as an energy-saving measure are now well established, organisations that own their HV transformers are often tempted to move to a lower tap setting in order to reduce site voltage, especially with ever increasing Grid voltages.


So-called –Tapping Down


The results in so-called Tapping Down in our experience, are often disappointing, with the energy savings derived from a maximum 5% tap-down settings producing a measly 1% “3% savings maximum.

For example:

Tesco and Sainsbury tapped down 300 HV transformers they owned by an average of 5% and achieved 1.5% – 2% savings over their entire estates.

A costly exercise for little gain.

J&A Young tapped down an HV transformer at their manufacturing site by 5% and achieved 0.2% saving.

A costly exercise for little gain.


Reason these savings are so low


The reason these savings are so low is that HV transformers are inherently inefficient, and waste even more energy once tapped-down.

In addition, due to the high impedance of the HV transformer and that the tappings are on the HV side, reducing the voltage will result in an increase in the current on the LV side.

This increases the I2R Copper heat losses in the transformer and increases the magnetisation currents or Iron losses, on the load site of the TX within inductive loads.

Even if you swap out and replace the current TX with Super low loss TX, the savings gain might only be 1% and with no guarantee in place.

If tapping down a transformer offers such low savings what might a better solution be?



Best option in our experience


The best option in our experience is a Voltage Optimiser, a voltage optimiser looks like a transformer from the outside, it smells like a transformer, and if you lick it it tastes like a transformer, but its not a transformer ,it’s constructed in a similar manner but with one crucial difference, it has a third and all important control winding.

This third winding captures the Back Electromotive Force (Back EMF) either as a fixed point optimisation or a dynamically controlled optimisation that mimics the rise and fall of the supply voltage during the day and night.. Using this technique allows for a much greater range of voltage suppression than can be achieved by tapping down alone, in turn producing much much greater cost savings.


will pay for itself from the savings in 1-3 years


For most sites, this form of Voltage Optimisation installation will pay for itself from the savings in 1-3 years, which represents a return on investment of 33% -100%.

An additional intangible benefit of Voltage Optimisation is the increase in site equipment lifetimes, and a reduction in wear and tear on all electrical plant improving whole site electrical O&M.

We can guarantee our Transformer Optimisers for 15 years ,whereas a standard ultra low loss transformer is only guaranteed for 1 year.

Our USP is that our savings proposals are also guaranteed for complete piece of mind

To find out if your site will benefit from Voltage Optimisation email us or call now.

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