4th Year Lineman Apprentice Practice Exam

When dealing with an autotransformer, the key aspect to understand is how the voltage is divided along the coil. An autotransformer uses a single winding that serves both as the primary and the secondary winding, with taps at various points along the winding to provide different voltage outputs.

In this scenario, if the high side of the autotransformer is supplied with 2400 volts, and a tap is taken from one end of the coil to the center of the coil, the voltage at the tap (the low side) will be a function of how the coil is divided.

Since the tap is at the center of the coil, it means that the total coil length can be thought of as being split evenly—one half is connected to the high side, and the other half is tapped at the center point. Therefore:

- The entire winding of the autotransformer provides 2400 volts across its full length (from one end to the other).

- Since the tap is at the midpoint, the voltage at the tap, which represents the low side, will be half of the total voltage supplied.

Calculating this gives us:

2400 volts (total voltage) ÷ 2 = 1200 volts.

Hence, the voltage