Such public utility shall, by written petition filed with the commission and setting forth the pertinent facts involved, make application to the commission for an order authorizing the proposed issue, assumption or guarantee of securities, and the application of the proceeds therefrom to the purposes specified. The commission shall, after such hearing and upon such notice as the commission may prescribe, enter its written order approving the petition and authorizing the proposed securities transactions, unless the commission shall find: that such transactions are inconsistent with the public interest; or that the purpose or purposes thereof are not permitted by this act; or that the aggregate amount of the securities outstanding and proposed to be outstanding will exceed the fair value of the properties and business of the public utility.