Starting methods of induction motors (December 2015 DOCX

Title	Starting methods of induction motors (December 2015
Author	Genesis Bebe
Pages	8
File Size	3.4 MB
File Type	DOCX
Total Downloads	310
Total Views	521

Summary

Synchronous motors and Synchronous condenser 1  Starting methods of induction motors (December 2015) Colcha Iván, IEEE, National Polytechnic School Abstract— Many methods can be used to start large AC induction motors. Choices such as full voltage,  Star-Delta Starter reduced voltage either by aut...

Description

Synchronous motors and Synchronous condenser Abstract— Many methods can be used to start large AC induction motors. Choices such as full voltage, reduced voltage either by autotransformer or wye-delta, a soft starter, or usage of an adjustable speed drive can all have potential advantages and trade offs. Reduced voltage starting can lower the starting torque and help prevent damage to the load. Additionally, power factor correction capacitors can be used to reduce the current, but care must be taken to size them property. Usage of the wrong capacitors can lead to significant damage. Choosing the proper starting method for a motor includes an analysis of the power system as well as the starting load to ensure that the motor is designed to deliver the needed performance while minimizing its cost. This paper examines the most common starting methods and their recommended applications. Index Terms— I. INTRODUCTION A 3-phase induction motor is theoretically self starting. The stator of an induction motor consists of 3-phase windings, which when connected to a 3-phase supply creates a rotating magnetic field. This will link and cut the rotor conductors which in turn will induce a current in the rotor conductors and create a rotor magnetic field. The magnetic field created by the rotor will interact with the rotating magnetic field in the stator and produce rotation. Therefore, 3-phase induction motors employ a starting method not to provide a starting torque at the rotor, but because of the following reasons; 1) Reduce heavy starting currents and prevent motor from overheating. 2) Provide overload and no-voltage protection. There are many methods in use to start 3-phase induction motors. Some of the common methods are; Direct On-Line Starter (DOL) Star-Delta Starter Auto Transformer Starter Rotor Impedance Starter Power Electronics Starter Direct On-Line Starter (DOL) The Direct On-Line (DOL) starter is the simplest and the most inexpensive of all starting methods and is usually used for squirrel cage induction motors. It directly connects the contacts of the motor to the full supply voltage. The starting current is very large, normally 6 to 8 times the rated current. The starting torque is likely to be 0.75 to 2 times the full load torque. Starting methods of induction motors (December 2015) Colcha Iván, IEEE, National Polytechnic School...