CAST RESIN TRANSFORMERS EDM

The technical choice of a transformer is based on a punctual analysis of the technical aspects whereas the economic anlysis isn’t done with the same attention.

Mostly the choice is based on the purchase cost or on the initial cost. But for a correct analysis of a transformer it is necessary to consider the running cost also (called Ce); it is the cost of the energy used by the transformer during its life. This element is very important if you consider the energetic saving that every concern has to take into account nowadays.

The running cost CE is given by the energy used from the transformer during its life. The losses which determine the energy usage are given by the empty losses Po and the charge losses Pc.

The empty losses Po are independent from the charge and are constant for all the time the transformer is connected to the line. The charge loss Pc are proportional to the voltage square and are variable from the charge oscillation.

The charge loss Pc are proportional to the voltage square and are variable from the charge oscillation.

In the following example you can notice an economic comparison between two resin transformers in terms of total cost (CT = Ci + Ce), considering the losses values.

Transformer A: transformer to reduced losses a lot (Zucchini).

Transformer B: transformer to normal losses.

cost kWh = 0,19€ (the energy cost is considered constant for all the 24 houres) i = 3% (annual interest on the capital)

Charge diagram of a small business in working days.

Ia: real voltage assimilated from the Transformer
In: nominal voltage of the transformer
G (working days): 220

Charge diagram of a small business in working days.

G (working days): 145

The result is that the A Transformer A is the less expensive after only two years of life. The Δ initial cost of 3.850€ is overcame and at the end of the Transformer life we have a saving of more than 28.000€.

To come to the conclusion the Δ initial cost isn't a good parameter for the Transformer choice but it must be considered as an investment. Namely with the considered hypothesis the final saving is seven times higher than the Δ initial cost and the investment income is of only two years.