Starting high-inertia loads

Common methods used to start AC induction motors driving high-inertia loads include across-the-line starting and reduced-voltage starting by autotransformer, wye-delta, or resistor/reactor. Application of these methods is generally well documented and understood. However, with the increased use of electronic soft starters and variable-frequency drives, applications can be markedly different. This paper reviews the aforementioned methods and explains the benefits and limitations of each. The effect of high-inertia loads on both acceleration time and motor heating is examined. A case history of starting a centrifuge with an electronic soft starter is studied. Finally, a comparison of all of the methods is presented with recommendations on choosing the proper starter given.