In a single-phase transformer with a nameplate voltage of 7200/480, what tap is used for a desired secondary voltage of 460V when the incoming voltage is 6,700V?

To determine the correct tap setting needed to achieve a desired secondary voltage of 460V, given an incoming voltage of 6,700V in a transformer with a nameplate rating of 7200/480V, it's important to analyze the voltage ratio and tap adjustment process.

The nameplate indicates that the primary side of the transformer operates at a voltage of 7200V and the secondary side at 480V. The voltage transformation ratio can be calculated as follows:

Voltage ratio = Primary voltage / Secondary voltage = 7200V / 480V = 15.

This means that for every 15 volts on the primary side, there is 1 volt on the secondary side. To find out what primary voltage is needed to achieve a secondary voltage of 460V, we can set up the ratio:

460V (desired secondary voltage) x 15 (transformation ratio) = 6900V (required primary voltage).

However, the incoming voltage is only 6,700V. To determine the appropriate tap that corresponds to the 6,700V primary while still allowing a secondary voltage of 460V, we look for a tap setting that brings the transformer into a working condition that allows for this output.

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