Definition
An electrical component that performs two functions in sequence: it transforms alternating current (AC) from one voltage to another, and then rectifies that AC into direct current (DC). In aircraft, transformer rectifiers are commonly used to convert the airplane's main AC bus power into the lower-voltage DC power needed to run avionics, lighting, and battery charging systems.
Plain English
A unit that takes one type of electrical power (AC at one voltage), changes it to a different voltage, and then converts it into the steady DC power that many aircraft systems need to run.
Context Anchor
Seen in aircraft electrical system descriptions, maintenance troubleshooting, and cockpit messages related to electrical power supply.
Derivation
Transformer comes from Latin trans- ('across') and formare ('to shape') — a device that 'shapes' electricity from one voltage to another. Rectifier comes from Latin rectus ('straight') — it 'straightens' alternating current, which flows back and forth, into direct current, which flows one way only. Put together, the name describes exactly what the unit does: it changes the voltage, then straightens the flow.
Why Pilots Care
It provides reliable DC power to critical systems such as radios, instruments, and lights; failure can cause loss of essential equipment.
Analogy
It is similar in purpose to a device charger that takes wall power and turns it into the kind of power your phone or tablet can use.
Intuition Check
A transformer rectifier is not a battery and it does not create power by itself. It converts electrical power from one usable form into another.
Example Sentence 1
The transformer rectifier converts 115-volt AC from the main bus into 28-volt DC for the aircraft's DC systems.
Example Sentence 2
During preflight checks the pilot verifies that both transformer rectifiers are operating normally.