Proper transformer sizing and copper windings

by E Swanepoel, Copper Development Association Africa (CDAA)

 

Published in: Transformers and Substations Handbook: 2014

Chapter 1: Design and manufacture of transformers - page 16

Enquiries: Email evert.swanepoel@copperalliance.org.za

 

Read the full article on Proper transformer sizing and copper windings in PDF format.

 

As shown, choosing a more efficient, copper-wound transformer that exceeds the minimum efficiencies of TP-1 (and Energy Star) can pay back its price premium in as little as one year.

Noteworthy is the fact that the TP-1 (Energy Star) efficiency, copper-wound transformer, loaded at 75 % of its nameplate capacity, saves over US $88 (ZAR 867) a year compared with an aluminium-wound TP-1 model, but costs only US $ 85 (ZAR 837) more initially. At only 50 % loading, the copper-wound transformer -TP-1 - saves about US $ 50 (ZAR 492) a year compared with the same aluminium unit. No-load loss is reduced from 350 to 320 W because the greater conductivity of copper windings allows a smaller core to be used, so energy continues to be saved even at light loading levels.

For even greater savings, the premium efficiency, copper-wound transformer saves over US $ 401 (ZAR 3 952) a year at 75 % loading, compared with the aluminium TP-1 model, and only costs an additional US $ 1 235 (ZAR 12 172).
Over such a long life span, the operating cost of a transformer can greatly exceed its initial price, so selection of the right transformer for economic performance involves examining the unit’s capacity (size) and efficiency. In this context, efficiency means looking at the core steel and the winding material.

Transformers remain a fundamental part of electrical distribution systems, and their correct sizing, for the load they are expected to carry and the material used in their internal copper windings, can dramatically impact these two aims. It is worth reiterating that the recommended loading for economic sizing of a transformer is typically around 75 % of nameplate and premium efficiency, copper-wound transformer, will result in significant savings in the long run.

 

Take note

  • The correct sizing for the load a transformer is expected to carry can impact its lifespan.
  • The recommended loading for economic sizing of a transformer is typically around 75 % of nameplate and premium efficiency, copper-wound transformer will result in savings.
  • Given their life span, buying a transformer based only on its initial cost is uneconomical.