SQL> create table test10
  2  (id number,
  3  name varchar2(10),
  4  d date);

Table created.

SQL> insert into test10 values(23, 'VJ', '11-Jul-2002 21:21:21')
  2  ;
insert into test10 values(23, 'VJ', '11-Jul-2002 21:21:21')
                                    *
ERROR at line 1:
ORA-01830: date format picture ends before converting entire input string

SQL> alter session set nls_date_format='dd-mon-yyyy hh24:mi:ss';

Session altered.

SQL>  insert into test10 values(23, 'VJ', '11-Jul-2002 21:21:21');

1 row created.

SQL> select * from test10;

        ID NAME       D
---------- ---------- --------------------
        23 VJ         11-jul-2002 21:21:21