hi

i have lack of knowledge about drives and i wanna  start studying about them is anyone to help how i can start and from which drive series its better to study first?

thx a lot

Well, Siemens have online quick course available for basics

http://www.sitrain-lms.com/step.aspx

Also, you can refer posts in different drive conferences 

For AC drives, read MM440 drive Operating instruction manual, personally i recommend for basic understandings of different functions of drives

Regards,

Devesh Vithani