Improved calculations for no-load transformer switching surges

Popov, Marjan; Sluis, L. van der

doi:10.1109/61.924818

Cited by 19 publications

(6 citation statements)

References 17 publications

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“…10 However, it will be shown in this study that the wave propagation of TOVs has a crucial impact on the magnitude and the time derivative of the TOVs. To analyze these fast phenomena on a very short timescale, a cable model including wave propagation and fre-…”

Section: System Modelingmentioning

confidence: 99%

Transients in collection grids of large offshore wind parks

2007

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Section: System Modelingmentioning

confidence: 99%

Transients in collection grids of large offshore wind parks

2007

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“…Particularly important is the analysis of a transformer system's exposure to overvoltages with nonstandard waveforms generated when switching transformers with vacuum circuit breakers. It is particularly important to identify the exposure of the insulation systems of internal transformer windings to overvoltages with atypical waveforms generated in systems with vacuum circuit breakers [17][18][19][20][21]. Internal overvoltages in transformers depend on the waveforms from external transient voltages and transient phenomena inside the windings.…”

Section: Introductionmentioning

confidence: 99%

Overvoltage Impact on Internal Insulation Systems of Transformers in Electrical Networks with Vacuum Circuit Breakers

et al. 2020

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Vacuum circuit breakers are increasingly used as switching apparatus in electric power systems. The vacuum circuit breakers (VCBs) have very good operating properties. VCBs are characterized by specific physical phenomena that affect overvoltage exposure of the insulation systems of other devices. The most important phenomena are the ability to chop the current before the natural zero crossing, the ability to switch off high-frequency currents, and the rapid increase in dielectric strength recovery. One of the devices connected directly to vacuum circuit breakers is the distribution transformer. Overvoltages generated in electrical systems during switching off the transformers are a source of internal overvoltages in the windings. The analysis of the exposure of transformers operating in electrical networks equipped with vacuum circuit breakers is of great importance because of the impact on the insulation systems of switching overvoltages (SO). These types of overvoltages can be characterized by high maximum values and atypical waveforms, depending on the phenomena in the circuit breaker chambers, system configuration, parameters of electrical devices, and overvoltage protection. Overvoltages that stress the internal insulation systems are the result of the windings response to overvoltages at transformer terminals. This article presents an analysis of overvoltages that stress the transformer insulation systems, which occur while switching off transformers in systems with vacuum circuit breakers. The analysis was based on the results of laboratory measurements of switching overvoltages at transformer terminals and inside the winding, in a model medium-voltage electrical network with a vacuum circuit breaker.

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“…Multiple reignitions can occur during the switching of transformers and motors with vacuum CBs (VCBs), because of the ability of VCBs to interrupt high-frequency currents. The development process of multiple reignitions has been traced in detail [14], [15]. It has been shown that the problem is not caused by the VCB or the transformer, but by an interaction of both [10].…”

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confidence: 99%