(a) If the commission finds an emergency to exist, that in the commission's judgment requires the adoption of an order without giving notice or holding a hearing, the emergency order may be adopted and shall be valid as though notice had been given and a hearing held.
(b) The emergency order shall remain in force no longer than 15 days from its effective date.
(c) The emergency order shall expire, in any event, at the time an order relating to the same subject matter and adopted after proper notice and hearing becomes effective.