Conventional alternators consist of two parts, a rotating part (rotor) and a stationary part (stator) which both have windings. When we take a closer look at the stator’s main winding, we will see that it can be connected in two different ways.
Explanation
In order to obtain an output power of 230V, the windings are placed in series (red). In order to obtain an output power of 115V, the windings are placed in parallel (green).
115V is used for specific construction tools and is still common in the United Kingdom. The plugs are easy to recognize by their yellow color.* For portable tools, 55V is more common because it is a much safer voltage.
110V CTE 55V - 0V - 55V
A CTE (Center Tapped Earth) is a grounded connection that is made from the center of the secondary winding. It is often used for portable tools in the United Kingdom.
The winding is split in two sides with each having only 55V compared to earth. This voltage can still be dangerous but it is better than the full 110V.
