1.1 Overview
Electric motors are the majority of the industry prime movers. Induction motor is the most popular ones for their reliability and simplicity of construction .although induction motors are reliable they are subjected to some mode of failures. These failures may be inherent to the machine itself or due to operating conditions. The origins of inherent failures are due to mechanical or electrical forces acting in the machine enclosure. Researchers have studied a variety of machine faults. Unexpected faults and failures in these machines can lead to excessive downtime and generates large revenue losses in terms of maintenance and production.
Induction motors are used worldwide as the workhorse in industrial applications. Such motors …show more content…
Mechanical stresses are caused by overloads and abrupt load changes, which can produce bearing faults and rotor bar breakage. On the other hand, electrical stresses are usually associated with the power supply. Induction motors can be energized from constant frequency sinusoidal power supplies or from adjustable speed ac drives. However, induction motors are more susceptible to fault when supplied by ac drives. This is due to the extra voltage stress on the stator windings, the high frequency stator current components, and the induced bearing currents, caused by ac drives. In addition, motor over voltages can occur because of the length of cable connections between a motor and an ac drive. This last effect is caused by reflected wave transient voltages. Such electrical stresses may Produce stator winding short circuits and result in a complete motor failure. Induction motor failures include bearing failures, inter-turn short circuits in stator windings, and broken rotor bars and end ring faults. Bearing failures are responsible for approximately two-fifths of all faults. Inter-turn short circuits in stator windings represent approximately one-third of the reported faults. Broken rotor bars and end ring faults represent around ten percent of the induction motor faults. Several alternatives have been used in industry to prevent severe damage to Induction motors from the above mentioned faults and to avoid …show more content…
This is called incipient failure detection. The incipient detection of motor failures also provides a safe operating environment. It is becoming increasingly important to use comprehensive condition monitoring schemes for continuous assessment of the electrical condition of electrical condition of electrical machines. By using the condition monitoring it is possible to provide adequate warning of imminent failure. In addition, it is also possible to schedule future preventive maintenance and repair work. This can result in minimum down time and optimum maintenance schedules. Condition monitoring and fault diagnosis scheme allows the machine operator to have the necessary spare parts before the machine is stripped down, thereby reducing outage times. Therefore, effective condition monitoring of electric machines is critical in improving the reliability, safety, and
Electric motors are the majority of the industry prime movers. Induction motor is the most popular ones for their reliability and simplicity of construction .although induction motors are reliable they are subjected to some mode of failures. These failures may be inherent to the machine itself or due to operating conditions. The origins of inherent failures are due to mechanical or electrical forces acting in the machine enclosure. Researchers have studied a variety of machine faults. Unexpected faults and failures in these machines can lead to excessive downtime and generates large revenue losses in terms of maintenance and production.
Induction motors are used worldwide as the workhorse in industrial applications. Such motors …show more content…
Mechanical stresses are caused by overloads and abrupt load changes, which can produce bearing faults and rotor bar breakage. On the other hand, electrical stresses are usually associated with the power supply. Induction motors can be energized from constant frequency sinusoidal power supplies or from adjustable speed ac drives. However, induction motors are more susceptible to fault when supplied by ac drives. This is due to the extra voltage stress on the stator windings, the high frequency stator current components, and the induced bearing currents, caused by ac drives. In addition, motor over voltages can occur because of the length of cable connections between a motor and an ac drive. This last effect is caused by reflected wave transient voltages. Such electrical stresses may Produce stator winding short circuits and result in a complete motor failure. Induction motor failures include bearing failures, inter-turn short circuits in stator windings, and broken rotor bars and end ring faults. Bearing failures are responsible for approximately two-fifths of all faults. Inter-turn short circuits in stator windings represent approximately one-third of the reported faults. Broken rotor bars and end ring faults represent around ten percent of the induction motor faults. Several alternatives have been used in industry to prevent severe damage to Induction motors from the above mentioned faults and to avoid …show more content…
This is called incipient failure detection. The incipient detection of motor failures also provides a safe operating environment. It is becoming increasingly important to use comprehensive condition monitoring schemes for continuous assessment of the electrical condition of electrical condition of electrical machines. By using the condition monitoring it is possible to provide adequate warning of imminent failure. In addition, it is also possible to schedule future preventive maintenance and repair work. This can result in minimum down time and optimum maintenance schedules. Condition monitoring and fault diagnosis scheme allows the machine operator to have the necessary spare parts before the machine is stripped down, thereby reducing outage times. Therefore, effective condition monitoring of electric machines is critical in improving the reliability, safety, and