power on

1. To connect to a power source to begin or resume normal function or operation. He began reading the memos for the day while waiting for the computer to power on. The lights in the warehouse are set to power on automatically at 8 AM each morning.

2. To activate an electronic device, appliance, tool, or piece of machinery by causing or prompting it to connect to a power source. A noun or pronoun can be used between "power" and "on." I always sit down at my desk and have a cup of coffee before I power on my computer and start work for the day. OK, power the machine on and release the emergency brake.