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A transformer is an electrical device that transfers energy from one circuit to another purely by magnetic coupling. Transformers are often used to convert between high and low voltages, to change impedance, and to provide electrical isolation between circuits.

A basic transformer consists of two sets of coils or windings close to each other (sometimes wrapped around an iron or ferrite "core"). Each set of windings is simply an inductor. Power is fed into one coil (the "primary"), which creates a magnetic field. The magnetic field causes current to flow in the other coil (the "secondary"). The alternating current that flows through the primary winding establishes a time-varying magnetic flux, some of which links to the secondary winding and induces a voltage across it. The number of times the wires are wrapped around the core ("turns") is very important and determines how the transformer changes the voltage.

•     If the primary has fewer turns than the secondary, you have a step-up transformer that increases the voltage.
•     If the primary has more turns than the secondary, you have a step-down transformer that reduces the voltage.
•     If the primary has the same number of turns as the secondary, the outgoing voltage will be the same as what comes in. This is the case for an isolation transformer.
•     In certain exceptional cases, one large coil of wire can serve as both primary and secondary. This is the case with variable auto-transformers.

A transformer doesn't change power levels. If you put 100 Watts into a transformer, 100 Watts come out the other end. Actually, there are minor losses in the transformer because nothing in the real world is 100% perfect. But transformers come pretty darn close; perhaps 95% efficient.

This 3-hr course provides a basic overview of transformers and is based entirely on Naval Education and Training Materials (NAVEDTRA 14174), Electricity and Electronic Training Series; Module-2 and covers Chapter 5, titled “Transformers”.

The student must take a multiple-choice quiz consisting of fifteen (15) questions at the end of this course to obtain PDH credits.

State Board Acceptance

This course can be used by professional engineers to fulfill PDH requirements mandated by state and provincial licensing boards. Decatur Professional Development is an approved provider of continuing education in all states that pre-approve course providers. In all other states that mandate continuing education for engineers, it is the individual engineer's responsibility to determine the suitability of activities for PDH credit. The state boards typically accept online* courses that cover technical, managerial** or ethical content and which are relevant to the practice of engineering. The course must have a clear purpose or objective with a content that will maintain, improve or expand the skills and knowledge of the licensee's field of practice. For questions about your mandatory PDH requirements, visit the website of your state licensing board.

*Online courses are accepted by all state licensing boards that mandate continuing education. Other than New York (which limits online courses to 18 PDH) and Iowa (which limits online courses to 6 PDH), there are no limits placed by other states on the number of hours that can be earned through online continuing education. Consult with your state licensing board if you have any questions about the acceptability of online courses.

**The New York State Board of Engineers does not accept general office management courses, but will accept project management courses that are offered by an approved provider and that are technical in nature and contribute to the engineer's professional practice.

Please Note: Continuing Education credits for this course are awarded as PDH (Professional Development Hour Credits).