How do I change the sleep mode setting on the HP DesignJet T520?

To change the sleep mode setting, go to the front panel and tap the settings icon, then select Printer preferences > Sleep, and select the wait time you want before tapping OK. You can set the time anywhere from 5 to 240 minutes, and the default time is 30 minutes. The printer will automatically enter sleep mode and switch off the front-panel display after the set period of inactivity to save power.