65 ILCS 5/11-119-3
Whenever bonds are issued under this Division 119, sufficient revenue received thereafter from the operation of the electric light plant and system, or the gas plant and system, as the case may be, to pay the cost of maintenance and operation of the plant and system, and the principal of and interest on all obligations payable from the revenues of such plant and system, including the bonds issued hereunder, without limiting the generality of the foregoing, shall be deposited in a separate fund, designated as the electric light fund of ...., or the gas fund of ...., as the case may be. This fund shall be used only in paying (1) the cost of maintenance and operation of the plant and system, (2) principal of and interest upon obligations, in whatever form, of the municipality theretofore issued that are payable by their terms from this revenue, and (3) bonds issued under this Division 119.
Rates charged for electric current or gas shall be sufficient to pay the cost of maintenance and operation and to pay the principal of and interest upon all of the specified bonds and obligations.
65 ILCS 5/11-119-3