Anode Spot Formation Threshold Current Dependent on Dynamic Solid Angle in Vacuum Subjected to Axial Magnetic Fields

Kong, Guowei; Liu, Zhiyuan; Ma, Hui; Xue, Xutian

doi:10.1109/tps.2013.2259182

Cited by 34 publications

(13 citation statements)

References 21 publications

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“…4, the high opening velocity corresponds to a low AMF of 2.8 mT at the center point of the anode at current peak, while the low opening velocity corresponds to a high AMF of 3.5 mT. The finding related to the influence of the opening velocities on the formation of the anode spot also agreed with [21].…”

Section: Effects Of Opening Velocity On Current Density Distributionsupporting

confidence: 78%

Anode Current Density Distribution Measurements for Different Vacuum Arc Modes Subjected to Axial Magnetic Field

Zhang

Liu

et al. 2015

IEEE Trans. Plasma Sci.

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We report our measurements of anode current density distributions for different modes in vacuum arc discharge using a split-anode and a cup-shaped axial magnetic field cathode configuration system. The modes investigated included the diffuse arc and anode spot. The anode surface was divided into four regions: one central region and three symmetricaldisposed peripheral annular-arc regions. Three different-sized central regions were selected with diameters of 12, 18, and 20 mm. The contact material was CuCr25 (25% Cr). The arc current in the tests ranged from 6 to 14 kA (rms) at 50 Hz. The opening velocities were 1.8 and 2.4 m/s, respectively. The currents of the four areas on the anode contact were measured by four Rogowski coils situated outside the vacuum chamber. The experimental results show the current density distribution in different arc modes. For the diffuse arc mode with arc currents of 6 and 8 kA (rms), the average current density in the central region at current peak ranged from 8.5 to 15.9 A/mm 2 . The anode spot current density ranged from 31.9 to 37.7 A/mm 2 , estimated from the current density in the eroded region caused by the anode spots covering the entire central region of diameters 12 and 18 mm, at currents of 12 and 14 kA, respectively, regarded as the lower limit current density of the anode spot. Moreover, the dependence of the current density distribution on opening velocity in diffuse arcs was slight. For the anode spots, the current density distribution with higher opening velocity was more concentrated.

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Section: Effects Of Opening Velocity On Current Density Distributionsupporting

confidence: 78%

Anode Current Density Distribution Measurements for Different Vacuum Arc Modes Subjected to Axial Magnetic Field

Zhang

Liu

et al. 2015

IEEE Trans. Plasma Sci.

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“…While, a low average opening speed over the full contact gap could possibly avoid the formation of footpoint mode and anode spot mode, attributing to the constraining effect of AMF on arc plasma. The higher the AMF intensity is, the lower the current density on local contact surface is to form an anode spot or footpoint [33]. Thus, the anode spot mode or footpoint mode could be avoided [34].…”

Section: Design Of Opening Speed Characteristicsmentioning

confidence: 99%

Design and short‐circuit current breaking test verification of a 72.5 kV single‐break fast vacuum circuit breaker

Guan

Yao

Chen

et al. 2022

IET Generation Trans & Dist

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Fast clearing of a short‐circuit fault is vital to increase the transmission capacity of power grid transmission lines and improve the transient stability of a power system. A fast vacuum circuit breaker (FVCB) is a good candidate to realize quick elimination of a short‐circuit fault. The original contribution of this paper is to present the design of a 72.5 kV single‐break FVCB and its verification of short‐circuit breaking performance. A specially designed 72.5 kV vacuum interrupter, with floating shields and reduced mass of moving components, was developed. An electromagnetic repulsion actuator was used to provide a high initial opening speed, V1, of 5 m/s over half of the full‐contact gap and a relatively low average opening speed, V2, of 1.59 m/s in the full contact gap of 30 mm. The high‐designed V1 and low‐designed V2 were achieved with the aid of a deliberately designed oil buffer. The opening and closing time of the designed 72.5 kV FVCB was 1.2 ± 0.04 ms and 18 ± 0.20 ms respectively. The terminal fault test duty of T100s(b), carried out on the 72.5 kV FVCB, demonstrated both the 40 kArms and 80 kArms short‐circuit current breaking performance. The short‐circuit current breaking arcing time windows of FVCB, including the minimum arcing time, the maximum arcing time, and the middle arcing time, was verified to fulfill the requirement of the international standard, IEC 62271‐100 2017, and the Chinese standard, GB/T 1984–2014, both for the 40 kArms and 80 kArms switching cases, respectively. Further development of the 72.5 kV single‐break FVCB would benefit the development of ultra‐ or extra‐high voltage FVCBs by reducing essential numbers of series‐connected breaking units.

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“…Generally, the anode spot is evaluated by the anode spot threshold current, at which the anode discharge mode changes from the diffuse arc mode to the anode spot mode. The influence of contact materials [13], [14], magnetic fields [15], [16], discharge geometry [17], [18], and current waveform [19], [20] on the anode spot threshold current has been studied by the researchers.…”

Section: Introductionmentioning

confidence: 99%

“…The transition condition from the diffuse arc mode to the anode spot mode is judged based on the previous experimental data [16], [17], in which the threshold currents for each corresponding discharge parameters were determined. Various discharge parameters are considered.…”

Section: Introductionmentioning

confidence: 99%

Anode Input Heat Flux Density in High-Current Vacuum Arcs as Anode Spot Formation

Zhang¹,

Liu

et al. 2022

IEEE Trans. Plasma Sci.

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In vacuum interrupters, anode spot significantly decreases the current interruption capability. Generally, the anode spot is evaluated by the anode spot threshold current. Unfortunately, as a circuit parameter, arc current cannot explain the anode spot formation from the physical point of view. This work proposes the heat flux density as a new parameter to evaluate the anode spot. The objective of this study is to determine the anode input heat flux density as anode spot formation. The heat flux density is numerically obtained by a twotemperature magnetohydrodynamic model. Based on a previous systematic experimental work over a wide range of discharge conditions, the calculated critical anode input heat flux density located in a narrow range from 7.3 × 10 8 to 11.3 × 10 8 W/m 2 . Compared with the arc current, the anode input heat flux density is a key parameter in the interaction between the vacuum arc column and the anode; moreover, the heat flux density has a close relationship with both the arc distribution and the anode activity. Therefore, heat flux density is a reasonable physical parameter to reveal the mechanism of the anode spot formation.

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Anode Spot Formation Threshold Current Dependent on Dynamic Solid Angle in Vacuum Subjected to Axial Magnetic Fields

Cited by 34 publications

References 21 publications

Anode Current Density Distribution Measurements for Different Vacuum Arc Modes Subjected to Axial Magnetic Field

Anode Current Density Distribution Measurements for Different Vacuum Arc Modes Subjected to Axial Magnetic Field

Design and short‐circuit current breaking test verification of a 72.5 kV single‐break fast vacuum circuit breaker

Anode Input Heat Flux Density in High-Current Vacuum Arcs as Anode Spot Formation

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