A center-tap transformer, also known as a split-phase transformer or a center-tapped transformer, is a type of single-phase transformer with a special secondary winding configuration. It is commonly used in various applications to provide a center-tapped secondary winding, which allows the generation of both single-phase and two-phase (split-phase) power.
Here’s how a center-tap transformer works:
- Primary Winding: The primary winding of a center-tap transformer is connected to the power supply, and it receives the single-phase alternating current (AC) voltage.
- Secondary Winding: The secondary winding of the center-tap transformer consists of two windings with a common center tap (midpoint). Each end of the secondary winding is connected to a terminal, while the center tap is left unconnected or connected to the ground, depending on the application.
When used to generate single-phase power, the two terminals of the secondary winding are used, and the center tap is left unconnected. In this configuration, the transformer behaves like a regular single-phase transformer, and the output voltage between either terminal and the center tap is equal to half of the total secondary voltage.
When used to generate two-phase power (also known as split-phase power), the center tap is connected to the ground or neutral, and the load is connected across the two terminals of the secondary winding. The voltage across each terminal and the center tap is 180 degrees out of phase with each other, resulting in two-phase power.
Center-tap transformers are commonly used in various applications, including residential electrical systems, where they provide a simple and cost-effective way to deliver both single-phase and two-phase power. In residential applications, center-tap transformers are frequently used to provide 120/240-volt split-phase power, which is commonly used to power homes in many regions.
One important point to note is that center-tap transformers are not suitable for three-phase power generation. For three-phase power, a different type of transformer configuration, such as Delta or Wye, is used. Center-tap transformers are specific to single-phase or split-phase applications.