⤷ Get power status

Use GetSystemPowerStatus function and SYSTEM_POWER_STATUS structure.

procedure TForm1.Button1Click(Sender: TObject);
var
  PowerStatus: TSystemPowerStatus;
begin
  GetSystemPowerStatus(PowerStatus);
  if PowerStatus.ACLineStatus=1 then
    Label1.Caption:='AC power online'
  else Label1.Caption:='AC power offline';
end;
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