Definition
A solid-state rectifier, typically a silicon-controlled rectifier (SCR), that converts alternating current to direct current only when a small triggering signal is applied to its gate terminal. Once triggered, it conducts current in one direction until the current drops to zero, allowing precise control over how much DC power passes through the circuit.
Plain English
A switchable one-way valve for electricity. It only lets current pass when you tell it to, and only in one direction. By controlling when it switches on, you control how much power gets delivered.
Context Anchor
Seen in aircraft electrical-system discussions, especially in power supplies, charging circuits, and voltage-control equipment.
Derivation
Rectifier comes from the Latin rectus, meaning 'straight' or 'right' — a rectifier 'straightens' alternating current into one-direction (direct) current. 'Controlled' is added because, unlike a plain rectifier that always conducts, this one only conducts when commanded.
Why Pilots Care
Controlled rectifiers are at the heart of modern aircraft voltage regulation and power conversion. When they fail, you can see symptoms like erratic charging, voltage spikes, or loss of DC power to avionics — issues that show up on the ammeter or as warning lights.
Analogy
Think of it like a one-way door with an electric latch. The door blocks flow until the latch is released, and then it only allows movement in one direction.
Intuition Check
Controlled does not mean the pilot directly controls it. It means the device is turned on by a small electrical signal inside the circuit.
Example Sentence 1
The voltage regulator uses a controlled rectifier to manage how much current flows from the alternator to the battery.
Example Sentence 2
In the power supply unit the controlled rectifier prevents reverse current while allowing the alternator output to be adjusted for stable instrument power.