Analysis of Comparison Between Direct Starting Method (Direct on Line) with Variable Speed Drive (VSD) in Three-Phase Induction Motors

Abstract

Electric motors are essential tools in the industrial world, frequently used to drive various industrial processes. Induction motors come in different capacities based on needs, and large-capacity motors generate high starting currents, which can potentially damage the motor. To minimize the risk of damage, an appropriate starting method is required. The Direct On Line (DOL) method is a simple, commonly used method due to its easy maintenance and economical installation. The Variable Speed Drive (VSD) method shows better operational efficiency. This study compares these two methods by conducting direct measurements at the Transmission and Distribution Laboratory of the University of North Sumatra. The calculation results show that the motor efficiency using the DOL method is 93.2%, while with the VSD method, it is 95.6%. This comparison indicates that the performance of VSD is superior to the DOL method.