Dear Kumar,
I don't know that on what basis you raised your query with reference to those who are drawing a salary of more than Rs.24,000-00. Even in the definition of the term "employee" under the Act, there is no reference to the amount of salary/wages drawn. Therefore, the very first point is that once the employment in a particular industry is brought under the schedule of the MW Act,1948 by the appropriate Govt. and minimum rates of wages are fixed, the employer has to simply implement it.
Second, the minimum wages fixed is common to all employees including juniors and seniors in terms of service. When a particular app.Govt deems it necessary to grant some additional benefit to employees in terms of their length of service, it is a welcome decision. Therefore, when such a new component is introduced by the Govt into the structure of the existing minimum wages, it automatically falls into the inclusive components of the term wages under the Act.
Therefore, you have to pay the so called "SSA" to all those categories of employees if their industry wages minus the excluded items [ u/s 2(h) ] fall short of the minimum wages fixed.