Basic Operation of a Transformer

In its most basic form, a transformer consists of:

• A primary coil or winding.
• A secondary coil or winding.
• A core that supports the coils or windings.

Refer to the transformer circuit in the figure below as you read the following explanation: The primary winding is connected to a 60 hertz AC voltage source. The magnetic field (flux) builds up (expands) and collapses (contracts) about the primary winding. The expanding and contracting magnetic field around the primary winding cuts the secondary winding and induces an alternating voltage into the winding. This voltage causes alternating current to flow through the load. The voltage may be stepped up or down depending on the design of the primary and secondary windings.

FIGURE