Transformer Rectifier Units (TRUs) serve what function in avionics power?

• A. Convert AC to regulated DC power and provide filtering for avionics.
• B. Store energy for starting.
• C. Generate AC power for avionics.
• D. Regulate engine RPM.

Answer: (A)

The main idea is that transformer rectifier units convert alternating current into clean, regulated direct current for avionics. They take AC from the aircraft’s power sources, use a transformer to match the voltage and provide isolation, then rectify the AC with diodes to produce DC. The circuitry that follows regulates and filters that DC, smoothing ripple and keeping the voltage within tight tolerances so sensitive avionics components operate reliably. In short, they turn AC power into stable DC power for avionics. They don’t store energy for starting, they don’t generate AC power, and they don’t control engine RPM, so those functions aren’t what TRUs provide.