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Partial Discharges in Motor Wires at PWM Voltages of Different Smoothness

Thomas Hammarström (Institutionen för material- och tillverkningsteknik, Högspänningsteknik) ; Tord Bengtsson (Institutionen för material- och tillverkningsteknik, Högspänningsteknik) ; Jörgen Blennow (Institutionen för material- och tillverkningsteknik, Högspänningsteknik) ; Stanislaw Gubanski (Institutionen för material- och tillverkningsteknik, Högspänningsteknik)
Proceedings of 2014 International Symposium on Electrical Insulating Materials (ISEIM 2014), June 1-5, 2014, Niigata City, Japan p. 184-187. (2014)
[Konferensbidrag, refereegranskat]

Author’s recent work has been focused on exploring possibilities for measuring partial discharges (PDs) under the action of pulse width modulated waveforms (PWM), which resulted in a development of an electrical measurement method adopted for such voltages. This solution allows a more flexible PD analysis since voltage shapes appearing in service can be utilized. In this paper, results are presented where several waveforms are applied to quantify the PD properties for motor wire test objects, starting from a non-filtered PWM waveform and continuing with gradually smoothened ones towards an AC voltage shape. The results suggest that non-smoothed PWM voltage introduces considerably more PDs and with larger magnitudes, which most probably influences the lifetime of the insulation system in all tested cases. Additionally, above a certain level of filtering, the use of lower carrier frequencies implies higher PD exposure, which suggests that the filters used should be evaluated together with the carrier frequency to ensure a longer lifetime of the insulation. It was also observed that the changes in duty cycle reduce the PD density at higher frequencies. This suggests that only applying square voltage waveforms with 50 % duty cycle for PD testing may fail to capture the actual stress inflicted.

Nyckelord: Measurements, Motor winding, Partial discharges, PWM, square like voltages, Twisted pair



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Denna post skapades 2014-06-27. Senast ändrad 2015-01-22.
CPL Pubid: 199843

 

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