org.gnome.settings-daemon.plugins.power sleep-inactive-ac-timeout
~$ gsettings get org.gnome.settings-daemon.plugins.power sleep-inactive-ac-timeout
7200
~$ gsettings set org.gnome.settings-daemon.plugins.power sleep-inactive-ac-timeout 10800
org.gnome.settings-daemon.plugins.power sleep-inactive-ac-timeout
~$ gsettings get org.gnome.settings-daemon.plugins.power sleep-inactive-ac-timeout
7200
~$ gsettings set org.gnome.settings-daemon.plugins.power sleep-inactive-ac-timeout 10800