The role of HV transformers is to reduce high voltage (HV) electricity from the grid, typically 11000V or 6600V, to low voltage (LV) electricity, typically 400V-433V, so that it can be used safely by end-users in commercial and industrial spaces. This process transforms the entire power to a site from high voltage to low voltage.
Can tapping my transformer achieve greater efficiencies?
With distribution transformers, voltage reduction can be achieved through changing the tappings of the transformer. By tapping, you can get different turns ratio and be able to control output and therefore achieve a form of voltage management. However, when you alter the tappings it effects the number of coils and therefore the impedance of the transformer. Consequently, this leads to an increase in the transformer current if the voltage is reduced, or a deduction in the transformer current in the event of an increase in voltage.
Ideally, HV transformers should not be tapped beyond the settings they were specified and built to. Utilising this as a method to reduce the voltage is inefficient due to the relationship between voltage and current. Reducing the voltage in the transformer output by 5% will increase the current by the same percentage. Using this example, the losses in the transformer would increase by 25%. In the case of a typical 1000kVA transformer with a load loss of 8kW, based on a 75% load, reducing the voltage by 5% will increase these losses to 10kW, which will increase the site consumption by 17,520kWh a year, therefore inflating the site’s energy bill.
For this reason, HV transformers should be set to a tap based on the site requirements such as site capacity to ensure that they operate at maximum efficiency.
An optimal alternative – Powerstar HV MAX
A better way to approach increasing the efficiencies of a distribution transformer can be found through Powerstar’s HV MAX. Firstly, by utilising the more efficient materials of amorphous alloy within its core, Powerstar HV MAX offers greater efficiencies and lower losses than traditional ageing CRGO transformers. When combined with LV voltage optimisation, it provides a solution capable of providing significant energy savings as a complete HV/LV solution, without negatively impacting the current and therefore performance of the transformer.
This offers numerous benefits to customers across a variety of applications including average energy consumption savings of 8-12% percent, of which up to 3% can be attributed to the highly efficient core material. The low voltage applications of HV MAX provide the many benefits of variable voltage optimisation including reduced CO2 emissions, longevity of electrical equipment and a cleansed and stabilised voltage output.
In contrast to tapping HV transformers, Powerstar’s voltage optimisation solutions are built bespoke and specifically designed to optimise the LV supply in line with the site’s requirements and electrical equipment’s design characteristics.
In conclusion, the combined solution of Powerstar HV MAX offers the benefits of an efficient distribution transformer with the tangible and 100% guaranteed voltage optimisation technology. This enables companies to upgrade their existing HV infrastructure while achieving the benefits of reduced, optimised voltage, without impacting on transformer efficiencies, in one investment.