Whenever the Commission, pending an investigation had upon its own motion, or upon complaint, is of the opinion and so finds after an examination of any report or reports, annual or otherwise, filed with the Commission by any public utility, together with any other facts or information which the Commission may acquire or receive from an investigation of the books, records, or papers, or from an inspection of the property of such public utility, that the net income of such public utility, after reasonable deductions for depreciation and other proper and necessary reserves, is in excess of the amount required for a reasonable return upon the value of such public utility’s property, used and useful in rendering its service to the public, and if the Commission is of the opinion and so finds in such cause that a hearing to determine all of the issues involved in a final determination of rates of service will require more than ninety days of elapsed time, the Commission may, in case of such emergency, enter a temporary order, after not less than ten days’ notice to such public utility of its contemplated action and affording to it reasonable opportunity to introduce evidence and to be heard thereon, fixing a temporary schedule of rates, which order shall be forthwith binding upon such public utility. But the Commission’s power to order reductions in rates and charges of any public utility by means of such a temporary order, is limited to reductions which will absorb not more than the amount found by the Commission to be in excess of the amount of income, as determined by the Commission, necessary to provide a reasonable return on the value of the property of such public utility as found by the Commission as aforesaid.