What is an isolation transformer and when is it used in LV systems?

• A. Provides galvanic isolation between primary and secondary windings and helps reduce ground loops and noise
• B. Steps voltage up and down by turns ratio
• C. Converts DC to AC
• D. Filters harmonic content only

Answer: (A)

An isolation transformer provides galvanic isolation between its primary and secondary windings, meaning there is no direct electrical connection between the input and output despite power transfer through magnetic coupling. This separation helps prevent ground-loop currents and reduces common-mode noise, which can improve safety and signal integrity in low-voltage systems.

It’s used when you want to isolate equipment from the building ground or other parts of the electrical system to prevent unwanted currents and interference from flowing through grounded paths. This is especially important for sensitive instrumentation, medical or audio equipment, and any setup where reducing earth-loop issues and noise is a priority, or where safety requires keeping the output electrically separate from the supply.

Stepping voltage up or down by turns ratio is a general transformer function, but it isn’t what defines an isolation transformer. Converting DC to AC is the job of an inverter, not a transformer. Filtering harmonic content can be a secondary benefit in some cases, but isolation transformers are not designed solely for harmonic filtering.