As per SEBI Regulations, settlement cycle for equity is T+2. This implies that if you sell equity shares on CM Segment, the sales proceeds will be available on the T+2 day. For F&O, all brokers are required to report on a daily basis to the exchange for the margin amount required and collected from the clients, with respect to the trades executed / open positions of the clients. For the purpose of margin reporting, sales proceeds which are not realised will not be considered. Hence if you have utlised your equity sales proceeds on T day to take positions in Derivatives then you would be levied with a margin penalty from the exchange which would be debited to your trading ledger.
However, you will be able to use these sales proceeds to buy Equity (delivery) and also trade intraday, since there is no concept of margin reporting in the Equity cash segment.