"Constant Voltage" Transformer Power Delivered Calculator

"Constant Voltage" Transformer Power Delivered

Voltage Rating of Transformer volts	Tap Rating watts
New Voltage volts	Power from Tap watts

Many people don't realize that a transformer labeled for use with a specific voltage will work just as well at other voltages. This calculator provides power delivered from a transformer tap when driven with other than the rated voltage.

Example: You are installing a distributed system with very long lines. To overcome line loss, you select a 140 volt system. Which transformer tap will feed 10 watts to a loudspeaker with a "70V transformer?

1. Enter values for both "Voltage Rating of Transformer" and "New Voltage"

2. Either:

Enter a value for "Tap Rating" to calculate the power output from the tap at the new voltage.
Enter a value for "Power from Tap" to calculate the correct transformer tap to achieve the desired power at the new voltage.

Equation used to calculate the data:

Pactual = (Vnew squared / Vrated squared) * Prated

Where:
Prated = transformer tap value
Pactual = new power from tap
Vrated = voltage rating of transformer
Vnew = new voltage