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What are voltage adjustment taps on Transformers ?

Issue:
Taps on Transformers

Product Line:
LV Transformers

Environment:
Applies to Low Voltage Transformers by SquareD/Schneider Electric

Cause:
Some Low Voltage Transformers are equipped with taps to compensate for less than ideal primary voltage

Resolution:

Voltage supplied to a Transformer may vary from nominal due to the distance from the substation or panel, or other factors. Higher or lower input voltage will result in higher or lower output voltage if there are no voltage adjustment taps present.
Taps provide a means of maintaining the appropriate magnetic flux levels in the Transformer to provide the Transformer`s rated secondary output voltage.
Taps are usually supplied on the primary or input side. A tap position below nominal will allow a lower than normal input voltage to be transformed into rated output voltage.
For example: A Transformer is rated for 480 volts nominal primary input with a 208 volt nominal secondary output. If the voltage supplied to the nominal tap position is 432, the output of the transformer will be 10% low or 187 volts. Adjusting the tap connection to match the supplied voltage to the rated tap voltage, in this case to the 432 volt position, will adjust the volts-per-turn to supply the full 208 volt output. The unit nameplate will instruct in the proper connection to accommodate the input voltage. The tap position which is the physical position of the tap should not be confused with its effect on the secondary voltage.


CTA-ID : 2034689
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