Definition
A protective feature in an aircraft electrical system that automatically disconnects the alternator or generator from the electrical bus when its output voltage rises above a safe limit, preventing damage to electrical and electronic equipment.
Plain English
If the alternator starts producing too much voltage, this safety feature shuts it off automatically so it doesn't fry the radios, instruments, and other electrical gear.
Context Anchor
Seen in aircraft electrical system discussions, abnormal procedures, and IFR planning where continued electrical power is important for instruments and radios.
Derivation
Over' means above a limit, 'voltage' is the electrical pressure pushing current through a circuit, and 'disconnect' means to break the connection. Put together: when voltage goes too high, the system breaks the connection.
Why Pilots Care
It prevents damage to avionics, reduces risk of electrical fires, and maintains continued safe operation of critical flight instruments.
Analogy
It works somewhat like a household breaker that trips to protect the wiring, except this one reacts to voltage that is too high and takes the charging source offline.
Intuition Check
Do not assume an overvoltage disconnect means all electrical power is gone immediately. It usually means the charging source has been removed, so the battery may still power the system for a limited time.
Example Sentence 1
After the alternator warning light came on, the pilot recognized that the overvoltage disconnect had likely tripped and began load-shedding non-essential equipment.
Example Sentence 2
During the preflight electrical check the pilot confirmed the overvoltage disconnect was armed and functional.