Protection and control of low voltage motors used in industrial applications

As low voltage motors are critical assets in today´s industrial applications this paper will review the applications of microprocessor-based protection and control on low voltage motors less than 600 V AC in industrial facilities. It will review principles of low voltage motor protection (thermal overload, ground fault, unbalance, etc.). In addition, the paper will discuss the starting control of low voltage motors and review the different starting types (Full Voltage Non-Reversing, Full Voltage Reversing, Two Speed, Wye-Delta, Inverter, Soft Starter). Communications play a key role in the starting and stopping of low voltage motors. This paper will also discuss several different starting/stopping controls using communication protocols, such as Profibus, DeviceNet and Modbus.