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Frequently Asked Questions

This section is for informational purposes only and should not be used as a design tool or to generate technical specifications. For further details, please contact CTI and discuss with a representative for clarification. Search for terms or questions by entering words or phrases in the text box and clicking Search, by selecting a category from the drop-down list and clicking Show. Then simply click on the linked term or question below.

Question: Aluminum versus Copper

Answer: This is mostly a matter of economics in which some manufacturers try to cut cost by reducing quality. An aluminum wire of the same diameter or cross sectional area has only about 60% of the conducting properties of an equivalent size copper wire. However, aluminum weighs considerably less than copper and if you treat the two metals on a pound versus cubic inch basis, there are about 3 cubic inches of aluminum for each cubic inch of copper. Since both metals are purchased on a cost per pound basis some manufacturers use aluminum, even though the resulting transformer is substantially larger than a quality copper transformer. Not all types of windings nor all sizes of transformers lend themselves to be adapted to both aluminum and copper windings. Transformers with aluminum windings must be oversized to the load and generally have about one fourth the life of a quality copper wound transformer. Aluminum wound transformers perform best in constant load applications and should not be used for intermittent or varying loads.

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