RDDS (rate of decrease of dielectric strength) measurement for gas circuit breaker

Hamada, Hiromu; Eto, Atsushi; Maekawa, Toshihiro; Koshizuka, Tadashi; Nishiwaki, S.; Miyake, N.; Arai, Kazuo; Kosakada, M.

doi:10.1109/tdc.2002.1177720

Cited by 11 publications

(2 citation statements)

References 1 publication

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“…The continuous reduction in the distance between the CB fixed and moving contacts reduces the CB dielectric strength (CBDS) at the rate of decrease of dielectric strength (RDDS). From the closing operation initiation instant onward, the CBDS curve can be modeled as an oblique line whose slope is equal to the RDDS with a negative sign [35].…”

Section: Flux Matching: Concept and Challengesmentioning

confidence: 99%

Mitigating the Inrush Current of V/V Transformers Using Railway Conditioners

Aghazadeh,

Hajipour,

et al. 2024

IEEE Access

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Inrush current is high-magnitude current drawn by power transformers upon energization. The severity of inrush current depends on factors such as the transformer's residual flux and the voltage phase angle at the energization instant. This paper proposes a flux matching method for the energization of V/V traction transformers to mitigate inrush current. This is achieved by adjusting the residual flux of the core to an appropriate reference value and then obtaining the proper energization instant. To this end, the method only requires knowledge of nominal voltage and excitation current, eliminating the need to acquire transformer's parameters/design information. The railway power conditioner, typically present at the low voltage side of the V/V transformer, is used as a current source to inject sinusoidal current into the transformer windings before its energization. The reference residual flux is calculated based on the circuit breaker operating characteristics. The energization instant is determined such that the adjusted flux density matches the steady-state flux expected with respect to the applied voltage. The proposed method is validated by conducting over 14,000 simulations under different conditions using PSCAD/EMTDC. The method is also implemented and successfully tested on a laboratory-scale test rig, which verifies its effectiveness in more realistic conditions.INDEX TERMS Inrush current, flux density, excitation current, railway power conditioners, V/V transformers.

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Section: Flux Matching: Concept and Challengesmentioning

confidence: 99%

Mitigating the Inrush Current of V/V Transformers Using Railway Conditioners

Aghazadeh,

Hajipour,

et al. 2024

IEEE Access

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“…The time interval between this electrical making of current and the mechanical touch of contacts depends on RDDS. RDDS shows the dielectric strength between the gaps of circuit breaker contacts [20]. Figure 1a shows the effect of RDDS on pre‐strike voltage during close operation.…”

Section: Introductionmentioning

confidence: 99%

Synchronous switching of uncompensated transmission line, by considering the effect of coupling voltage between the phases, trapped charge and the characteristics of CB

Karimonnafs

2023

IET Science Measure & Tech

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The synchronous closing technology is an effective way to reduce transient current and voltage, prevent equipment failures, and improve power quality. The proposed algorithm, first by considering the coupling voltages between phases and the residual voltages in an uncompensated transmission line, calculates the zero instant of the voltage curves (ZVC instant) across the poles of the circuit breaker (CB) that is ideally the optimum instant to close the CB. Although other studies have utilized ZVC detection by solely considering either coupling or residual voltages. Secondly, the algorithm seeks to account for the mechanical scattering time of the CB and the rate of decrease of dielectric strength (RDDS) by incorporating delay times into the previously calculated delay values. Although other works have investigated the effect of RDDS or mechanical scattering operation time on synchronous switching to some extent, they have not fulfilled any optimization taking both of them into account.By exerting this algorithm, each phase of CB is closed in the ideal optimum closing target (ZVC instant) with a maximum error of one sample, and then, taking into account the CB characteristics, by compensating the RDDS and mechanical scattering time, CB is energized in the optimal time interval, where pre‐strike voltages are minimized.

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Research on controlled switching in reducing unloaded power transformer inrush current considering circuit breaker's prestrike characteristics

Chun-en

Zhang

et al. 2016

2016 27th International Symposium on Discharges and Electrical Insulation in Vacuum (ISDEIV)

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RDDS (rate of decrease of dielectric strength) measurement for gas circuit breaker

Cited by 11 publications

References 1 publication

Mitigating the Inrush Current of V/V Transformers Using Railway Conditioners

Mitigating the Inrush Current of V/V Transformers Using Railway Conditioners

Synchronous switching of uncompensated transmission line, by considering the effect of coupling voltage between the phases, trapped charge and the characteristics of CB

Research on controlled switching in reducing unloaded power transformer inrush current considering circuit breaker's prestrike characteristics

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