HI navin kumar ,
The section 40A(3) is reproduced for your kind information.
" Where the assessee incurs any expenditure in respect of which a payment or aggregate of payments made to a person in a day, otherwise than by an account payee cheque drawn on a bank or account payee bank draft, exceeds twenty thousand rupees, no deduction shall be allowed in respect of such expenditure. "
If you have paid to the same person through 3 vouchers in a single day then sec 40A(3) would be attracted as the words "aggregate of payments" implies apparently from the act.
If you have paid to different persons through 3 vouchers in any day the sec 40A(3) would not be attracted as the word " a person " implies apparently