The Journal of Engineering
Volume 2019, Issue 4, April 2019
Volumes & issues:
Volume 2019, Issue 4
April 2019
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- Author(s): Milton Castro-Núñez ; Deysy Londoño-Monsalve ; Róbinson Castro-Puche
- Source: The Journal of Engineering, Volume 2019, Issue 4, p. 3409 –3417
- DOI: 10.1049/joe.2019.0048
- Type: Article
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p.
3409
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(9)
Presently, it is not possible to corroborate Tellegen's theorem or to articulate the compensation theorem in the frequency domain when considering all the harmonics simultaneously. The circuit analysis approach based on geometric algebra is used here to solve these two challenges. We show here the significance of representing harmonics by k -vectors and how k -vectors process the magnitude, the phase and the frequency of a sine wave. We take a tutorial approach and provide examples to demonstrate both, the simplicity of this approach and how a distinct representation of time-domain signals of different frequencies facilitates both, energy analysis and confirming the principle of superposition and Kirchhoff's circuits’ laws in non-sinusoidal conditions when considering all the harmonics simultaneously.
- Author(s): Xun Zhang ; Kai Dai ; Wei Niu ; Rongbin Xie ; Huarong Zeng ; Yi Wen ; Xiaohong Ma
- Source: The Journal of Engineering, Volume 2019, Issue 4, p. 3418 –3424
- DOI: 10.1049/joe.2018.5468
- Type: Article
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p.
3418
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This study analyses a gas insulated switchgear explosion accident caused by a failure of the circuit breaker (CB) in a thermal power plant, which resulted in the explosion of the CB and the burning of the potential transformer (PT). Through X-ray detection and disassemble examination of the damaged CB, it is found that the A-phase moveable contact was not opened completely. After analysing the voltage waveform obtained from the phasor measurement unit recorder system, it is speculated that this failure is caused by the process of repeated arc strike. For verification and further analysis, the fault process is simulated in the EMTP; the arc is properly modelled by an extended KEMA's equation-based model which is proposed in this study. The simulation results match well with the actual situation; the contact gap would be repeated breakdown because its breakdown voltage is reduced, and the very fast transient overvoltage (VFTO) would be generated in these repeated strike processes. Due to the steep front and high amplitude of VFTO, the insulation of the PT would be damaged and led to the occurrence of PT short-circuit fault. The current would increase rapidly and causes the CB to explode subsequently.
- Author(s): Shizhou Lu ; Yuankai Ren ; Xiran Wang ; Xuguang Dong
- Source: The Journal of Engineering, Volume 2019, Issue 4, p. 3425 –3431
- DOI: 10.1049/joe.2018.5064
- Type: Article
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p.
3425
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The separating and screening of cylindrical parts are always difficult in the assembly industry, and the previous devices have the weakness of low working efficiency, low accuracy, and low automaticity. Based on the theoretical analysis, modelling and simulation, a theory of simultaneous separation and equidistant screening is proposed, and the corresponding equipment is established with the core modules of the multi-grooved cylindrical cam mechanism, pneumatic system, sensing, and controlling system. Solidworks software is used for three-dimensional modelling and kinematic simulation, which verify the correctness of the equipment design.
Theorems of compensation and Tellegen in non-sinusoidal circuits via geometric algebra
Simulation and analysis of a gas insulated switchgear explosion accident caused by a failure of high-voltage circuit breaker in a thermal power plant
Design and implementation of multi-grooved simultaneous separation and screening equipment
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