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A number of generator issues are undetectable using the generator terminal voltage or current measurements. For example, a switching element failure in the exciter produces a characteristic harmonic signature in the field current. While some generator protective relays are capable of measuring the field current, the sampling rate may be insufficient to extract the relevant harmonics. Consider shaft...
Eddy current loss in rotor permanent magnet can cause magnet heating and even demagnetization. It is much worse in machines equipped with fractional-slot concentrated-windings (FSCW). The paper analyzes harmonics of magnetic flux in airgap, slot harmonics, spatial harmonics and temporal harmonics of the magneto-motive-force (MMF). The relationship between the rotor magnet loss and air-gap size is...
This paper addresses the security of transformer differential protection with low levels of second harmonic during magnetizing inrush conditions. The paper explains the phenomenon of ultrasaturation causing the second harmonic to drop below the traditional 15 to 20 percent setting levels and points to possible causes of and conditions for ultrasaturation. A number of field cases are presented and...
Three harmonic mitigation techniques are presented to reduce the harmonic emission of a diode bridge rectifier based battery charger used to recharge the main propulsion batteries of a large scale electric vehicle. The hybrid electrical vehicle (HEV) studied here, uses a battery charger that produces current harmonics in excess to cause the control circuitry of the battery chargers to malfunction...
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