Why does a voltage step regulator need a two fingered, center tapped bridging reactor?

A voltage step regulator requires a two-fingered, center-tapped bridging reactor primarily to eliminate power interruption between tap changes. During the operation of a step voltage regulator, it needs to adjust the voltage levels as the load changes. The tap changing mechanism allows for incrementally adjusting the voltage output by switching between different transformer taps.

The bridging reactor acts as an intermediate component that accommodates the transition between taps without interrupting the current flow. This design ensures that the transfer occurs smoothly, preventing any momentary loss of power that could disrupt the electrical service. By employing this configuration, the system can maintain a consistent voltage level and reliable operation, which is crucial for electrical systems that require uninterrupted service to their loads.

Although considerations like efficiency, cost, and safety are important in electrical design, the primary function of the two-fingered reactor in this context is specifically to maintain continuity of power during tap changes.