how to login oracle sys as sysdba?

[regeszter]

ZZOraSqlDatabase1.Database:=test;
ZZOraSqlDatabase1.Login:='sys';
ZZOraSqlDatabase1.Password:='pwd';
ZZOraSqlDatabase1.Connected:=true;

ora-28009: connection to sys should be as sysdba or sysoper

ZZOraSqlDatabase1.Login:='sys as sysdba'; is not working

I can login to oracle as a normal user but not as sysdba.
Can anyone help me?

thx