The nature of vibration in electric machinery

DURING the past few years the progress made in reducing vibration in electric machinery has resulted in more freedom from mechanical failures and other maintenance troubles. The more quiet machines which result from reduced vibration also produce less nervous strain to the operate. The generally accepted theory of vibration is based on the premise that vibration and noise arise from forces which act in a periodic manner upon the different component parts of the machine. Such forces are called “driving forces.” and the actual mechanical displacement or vibration which results is frequently called the “vibrational response.” The amplitude of the vibrationa¹ response depends upon the amplitude of the driving forces as well as upon the mass, stiffness, and damping factors associated with the vibrating member. While this fundamental concept is quite simple, yet to account for particular types of vibration which are produced in electrical equipment and mechanical rotating assemblies is sometimes quite difficult.