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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: Duty Cycles of Transformers

Answer: In many applications, a transformer will not be called upon to provide the maximum amount of current required by a system on a continuous basis. Just like motors which are rated by a duty cycle calculation, a transformer rated for continuous duty will be bigger and more expensive than one rated for partial duty. In typical machine tool application, for example, a duty cycle of 50% is assumed. By calculating the percentage of full-load use required you can properly size both the transformer and motor in a system. The square root of the duty cycle times the full-load KVA requirement gives the effective KVA rating required for the transformer. For example, take a 50% duty cycle for which the square root is .71. Thus, the transformer will have to be 71% of the full-load rating.

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