Can somebody help me about the difference in Siemens Simovert Invertors 6SE7031-0EE20 and 6SE7031-0EE60. We actually require 6SE7031-0EE20 invertor but we do not have that in spare with us. 6SE7031-0EE60 is availible in the market and will it be comletely competible with the first one?