Abstract
Abstract : Medium Voltage (MV) Induction Motors (IMs) are widely used in industrial processes for many applications. This is due to their robust property, low maintenance and low cost. The purpose is to drive pumps, fans, compressors, blowers, conveyor belt, machine tools, elevators, mills and packaging equipment. These machines operate under high ambient temperatures, high moisture and dusty environment etc. Such environment can lead to motor damage resulting in unexpected maintenance downtime, high repair expenses, and production losses. IM are susceptible to several faults in industrial applications. If the fault is not identified at an early stage may lead to catastrophic failure resulting in severe damage to the motor. To provide reliable Condition Monitoring (CM) and protection technologies for medium voltage induction motors; this research focuses on determining the causes of IM failure in the Eskom power utility and proposing continuous on-line Condition Monitoring and protection methods which can detect, diagnose and prevent catastrophic failures in IM. A case study was conducted at Eskom Generation coal fired power stations on different type of MV squirrel cage IM ranging from nominal Voltage 3.3kV to 11kV supplied from 50Hz three phase source operating above 75% of full load current conditions. A comprehensive review of different condition monitoring and protection technologies was presented in this research. It was found that the factors leading to IM failure in Eskom power station are mechanical stress, electrical stress, environmental stress and abnormal operating conditions. The highest rate of failure is caused by mechanical stress with bearing failure being the most constitute followed by the stator failures. It was also found that there are certain CM and protection techniques not installed on motors to detect and diagnose faults. The power utility can accumulate revenue savings and prevent loss of production if these technologies are installed. This research further proposes strategies on how to conduct proper planning before implementing the proposed technologies and how to conduct risk analysis considering financial constraints in order to assist management in decision making on allocating funding to projects of higher priority.
M.Ing. (Engineering Management)