Income tax related query

Dear Sir, Purchase of Used WTG machines ( wind mills ) Depreciation benefits under IT Act. We plan to purchase WTG machines originally installed in the year Mar-2006. In this context, we are under the impression that the used WTGs are eligible for the accelerated deprecation rate of 80%, where as few opinions are against our understanding that used WTGs are eligible only for normal depreciation rate. Can you please advise.