No person subpoenaed or ordered shall be excused from attending and testifying or from producing books, records, correspondence, documents, or other evidence in any investigation or inquiry by or hearing before the commission or any commissioner upon the ground that the testimony or evidence required of the person may tend to incriminate the person or subject the person to a penalty or forfeiture. No person shall be prosecuted or subjected to any penalty or forfeiture for or on account of any act, transaction, matter, or thing concerning which the person is compelled, after having claimed the privilege against self-incrimination, to testify or produce evidence. The provisions of this section shall not exempt any person from prosecution or punishment for perjury. Nothing herein contained shall be construed as in any manner giving to any public utility immunity of any kind.