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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: Paralleling Transformers

Answer: Transformers can be paralleled when their voltages are equal. If the voltages are not equal, the difference between the voltages will result in a net voltage which will cause current to circulate on the closed network between the two transformers. This will cause false loading and, if there is enough difference between the two voltages, the transformers may actually burn out without any useful load being connected to them. In order to have transformers with like voltages share the load proportionately, their impedance's must be similar. In most commercial installations a tolerance of 10% impedance is permissible when transformers are paralleled. Three phase transformers must have similar angular displacement, meaning the phasing must be the same on each transformer.

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