noun, noun which may take the genitive case particle 'no'
in operation; in use; in action
Describes a machine or device that is currently running or active. Often used for security cameras, monitoring equipment, and automated systems. Can modify nouns with の.
The security camera is in operation 24 hours a day.
The room with the air conditioner running is cool.
動作中 is a broader term for 'in operation' or 'running', used for software, robots, and general mechanical actions, whereas 作動中 emphasizes the device's active state.
Compound of 作動 (sadō, 'operation') + 中 (chū, 'in the middle of'). 作動 is itself a compound of 作 (sa, 'make') and 動 (dō, 'move').