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Members: FreePES
IEEE Members: $25.00
Non-members: $40.00Pages/Slides: 57
Panel
14 Sep 2022
This panel session contains the following presentations:
1. A Case Study on Failures of Low Speed Medium Voltage Induction Motors Driving Reciprocating Compressors
This is a case study documenting a short experience with two large induction motors driving large reciprocating compressors in a refinery. The first motor is a 6.6kV 920kW and the second motor is an 11kV 3400kW. There are several considerations that need to be considered to ensure successful application of induction motors to reciprocating compressors. In this experience, several catastrophic failures have occurred and we concluded that the essential considerations are not applied during driver selections.
2. Reduction of Electric Stress in High Voltage Motor Insulation by Adjusting Individual PWM Flanks
The widespread use of inverter driven high voltage motors fed by pulse width modulated (PWM) inverters improve the efficiency and controllability. The electrical stress is however observed to increase which influence the ageing of the high voltage insulation system. One of the most important factors behind failure and increased stress is the appearance of partial discharges (PDs). This paper present observed changes in the PD characteristics within a high voltage mica- epoxy based motor insulation systems exposed to a three-level inverter waveform with controllable rise time. To compare the performances, measurements of PD characteristics were conducted and compared for the different cases. Specifically, the total number of PDs and their amplitude per cycle were obtained at 2 kV pp. The experimental results showed that the total summed PD magnitude drops considerably when adjusting the filtering level. However, the maximum PD magnitude remain at the same level for the same rise time in both cases. Also, the extinction voltage changes towards what is observed for sinusoidal exposure The PD magnitude decreases for increased rise time at the filtered flanks. Thus, the presented approach show that filtering of selected voltage flanks can be sufficient for reducing electrical stress considerably. This can increase the insulation life of the motor. Presented results show limitations and recommendations on how the waveform should be adapted to reach successful results close to when utilizing sinusoidal waveforms. Additionally, examples which show how the PD characteristics changes for different cases to provide further understanding of the PD phenomenon is included.
3. Impact of Coil Arrangements on the Electromagnetic and Thermal Performance of a Switched Reluctance Motor at Low Speeds
A Switched Reluctance Motor (SRM) is designed for an electric three-wheeler. One issue of concern for electric motors in electric vehicle application is the low efficiency at low speeds. This is addressed in this article by modifying the coil arrangements in the motor phase winding. Electromagnetic analysis for the designed motor with various coil arrangements is performed. The thermal signatures of the motor due to the change in coil arrangements are also studied.
1. A Case Study on Failures of Low Speed Medium Voltage Induction Motors Driving Reciprocating Compressors
This is a case study documenting a short experience with two large induction motors driving large reciprocating compressors in a refinery. The first motor is a 6.6kV 920kW and the second motor is an 11kV 3400kW. There are several considerations that need to be considered to ensure successful application of induction motors to reciprocating compressors. In this experience, several catastrophic failures have occurred and we concluded that the essential considerations are not applied during driver selections.
2. Reduction of Electric Stress in High Voltage Motor Insulation by Adjusting Individual PWM Flanks
The widespread use of inverter driven high voltage motors fed by pulse width modulated (PWM) inverters improve the efficiency and controllability. The electrical stress is however observed to increase which influence the ageing of the high voltage insulation system. One of the most important factors behind failure and increased stress is the appearance of partial discharges (PDs). This paper present observed changes in the PD characteristics within a high voltage mica- epoxy based motor insulation systems exposed to a three-level inverter waveform with controllable rise time. To compare the performances, measurements of PD characteristics were conducted and compared for the different cases. Specifically, the total number of PDs and their amplitude per cycle were obtained at 2 kV pp. The experimental results showed that the total summed PD magnitude drops considerably when adjusting the filtering level. However, the maximum PD magnitude remain at the same level for the same rise time in both cases. Also, the extinction voltage changes towards what is observed for sinusoidal exposure The PD magnitude decreases for increased rise time at the filtered flanks. Thus, the presented approach show that filtering of selected voltage flanks can be sufficient for reducing electrical stress considerably. This can increase the insulation life of the motor. Presented results show limitations and recommendations on how the waveform should be adapted to reach successful results close to when utilizing sinusoidal waveforms. Additionally, examples which show how the PD characteristics changes for different cases to provide further understanding of the PD phenomenon is included.
3. Impact of Coil Arrangements on the Electromagnetic and Thermal Performance of a Switched Reluctance Motor at Low Speeds
A Switched Reluctance Motor (SRM) is designed for an electric three-wheeler. One issue of concern for electric motors in electric vehicle application is the low efficiency at low speeds. This is addressed in this article by modifying the coil arrangements in the motor phase winding. Electromagnetic analysis for the designed motor with various coil arrangements is performed. The thermal signatures of the motor due to the change in coil arrangements are also studied.
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