Transformers have thousands of uses.
Many arbitrary ways of naming or labeling transformers apply to either their use, their method of manufacture or both. All transformers change both potential (or voltage) and current, but the more important change for the application influences the name.
Transformer Theory
A transformer induces electricity applied to a primary coil of wires into a secondary coil of wires. The number of turns of wire in each coil determines the potential or current induced.
Turns Ratio
A transformer with twice as many turns in the secondary as in the primary will double the voltage but halve the current. If reversed it halves the voltage and doubles the current.
Potential Transformers
Potential, power, or voltage transformers change commercial power from generators to high voltage and low current for nationwide distribution. Substations use similar transformers in reverse to reduce the voltage and increase the current to usable levels.
Other Potential Transformers
In the home and in industry, potential transformers have thousands of other uses. Your TV set as well as your cell phone charger have potential transformers to raise or lower the voltage for internal distribution and use.
Current Transformers
Transformers designated as current transformers have far more limited uses. Current or current sense transformers only lower current for use in meters and measuring devices, with little regard for power or voltage changes.
