Definition
An electrical coil rated to carry its specified current continuously without overheating or suffering damage. The coil is designed so that the heat it generates while energized is dissipated as fast as it is produced, allowing it to remain energized indefinitely.
Plain English
A coil that can stay switched on for as long as you like without getting too hot or burning out.
Context Anchor
Seen in aircraft electrical-system maintenance, especially when selecting or inspecting relays, contactors, or solenoids that may stay energized during operation.
Derivation
“Coil” refers to wire wound in loops. “Indefinite” means the time is not fixed or predetermined. Together, the phrase points to a coil that is not limited to a short burst of use, but is meant to remain powered for as long as the system needs it.
Why Pilots Care
Some aircraft components — like a master contactor or fuel boost pump relay — stay energized for the entire flight. They must be built with coils rated for continuous duty so they don't overheat and fail in flight.
Intuition Check
“Indefinite” does not mean “forever under any conditions.” Here it means “no short time limit when used within the coil’s rating.”
Example Sentence 1
The master contactor uses a coil rated for an indefinite period of time, so it can remain energized throughout the entire flight.
Example Sentence 2
After the test flight was scrubbed, the crew chose to coil for an indefinite period of time rather than disassemble the setup.