Definition
A short-duration performance rating assigned to a piece of electrical or electromechanical equipment, indicating the maximum continuous load the device can carry for twenty minutes without exceeding its allowable temperature limits, starting from a cold (ambient temperature) condition. After operating at this rated load for twenty minutes, the equipment must be allowed to cool back to ambient temperature before being operated at the rated load again.
Plain English
A label on a piece of equipment that says: 'You can run me at this load for up to twenty minutes before I get too hot. After that, let me cool all the way down before running me hard again.'
Context Anchor
Seen in aircraft battery specifications, maintenance records, and discussions of battery performance under heavy electrical load.
Why Pilots Care
Staying within this limit prevents overheating and mechanical stress that could force an early engine overhaul or failure.
Intuition Check
Do not read this as simply “the battery lasts 20 minutes.” It means the battery is tested at a specified current for 20 minutes and must keep its voltage high enough during that time.
Example Sentence 1
The starter motor carries a twenty-minute rating, so the checklist limits cranking attempts and requires a cooling period between starts.
Example Sentence 2
After the twenty-minute rating period ended, the crew reduced power to the maximum continuous rating.