Abnormal Arc Research Articles

Research on Abnormal Arc Extinguishing Phenomenon Under Low Vacuum Environment for Electrified Transportation

Research on Abnormal Arc Extinguishing Phenomenon Under Low Vacuum Environment for Electrified Transportation

Research on the Welding Process and Weld Formation in Multiple Solid-Flux Cored Wires Arc Hybrid Welding Process for Q960E Ultrahigh-Strength Steel.

This paper proposes a novel welding process for ultrahigh-strength steel. The effects of welding parameters on the welding process and weld formation were studied to obtain the optimal parameter window. It was found that the metal transfer modes of solid wires were primarily determined by electrical parameters, while flux-cored wires consistently exhibited multiple droplets per pulse. The one droplet per pulse possessed better welding stability and weld formation, whereas the short-circuiting transfer or one droplet multiple pulses easily caused abnormal arc ignition that decreased welding stability, which could easily lead to a "sawtooth-shaped" weld formation or weld offset towards one side with more spatters. Thus, the electrical parameters corresponding to one droplet per pulse were identified as the optimal parameter window. Furthermore, the weld zone (WZ) was predominantly composed of AF, and the heat-affected zone (HAZ) primarily consisted of TM and LM. Consequently, the welded joint still exhibited excellent mechanical properties, particularly toughness, despite higher welding heat input. The average tensile strength reached 928 MPa, and the impact absorbed energy at -40 °C for the WZ and HAZ were 54 J and 126 J, respectively. In addition, the application of triple-wire welding for ultrahigh-strength steel (UHSS) demonstrated a significant enhancement in post-weld deposition rate, with increases of 106% and 38% compared to single-wire and twin-wire welding techniques, respectively. This process not only utilized flux-cored wire to enhance the mechanical properties of joints but also achieved high deposition rate welding.

Multi-spectral Characteristics of Arc Discharge in Switch Cabinet

The partial discharge (PD) in high voltage switch cabinet might develop into non-penetrating or penetrating arc under extreme conditions, which can lead to insulation failure in severe case. From the optical radiation characteristics of discharge, an optical detection method for abnormal arc was proposed. Multi-spectral characteristics of arc discharge were obtained by the synchronous monitoring of ultraviolet, visible, and infrared optical signals, and the average intensity of light pulse, average light intensity ratio and the light intensity ratio of three bands were analyzed. The results show that the average light pulse intensity of arc discharge and the proportion of three-band light intensity have obvious characteristics and there is a good corresponding relation between the amplitude of discharge light signal and the applied voltage.

Lipschitz geometry and combinatorics of abnormal surface germs

We study outer Lipschitz geometry of real semialgebraic or, more general, definable in a polynomially bounded o-minimal structure over the reals, surface germs. In particular, any definable Hölder triangle is either Lipschitz normally embedded or contains some “abnormal” arcs. We show that abnormal arcs constitute finitely many “abnormal zones” in the space of all arcs, and investigate geometric and combinatorial properties of abnormal surface germs. We establish a strong relation between geometry and combinatorics of abnormal Hölder triangles.

Research on non-contact ultrasonic vibration assisted rotating electrical discharge machining (EDM) machine tool

Electrical discharge machining (EDM) is a nontraditional machining method by using pulsed spark discharge between workpiece and electrode to melt and remove metal. The traditional power supply method uses carbon brush and slip ring. This contact type has power supply at the contact point. Problems such as carbon deposition, leakage, and easy generation of electric sparks restrict the improvement of the rotation speed of the electrode and pose a safety hazard. The non-contact power supply technology based on the principle of electromagnetic induction can effectively solve the above problems, which can provide conditions for high-speed rotation of the electrode. In order to improve the processing quality and efficiency, this study aimed to design a small ultrasonic vibration assisted EDM machine, which can effectively avoid spark concentration and abnormal arc generation.

A New Algorithm for Detecting Failure to Clear Mode of Circuit Breakers Using Fundamental Frequency Component of Voltage Signals

This paper introduces a new algorithm for the early detection of abnormal arcing conditions of circuit breakers (CBs). Any interruption with a higher arcing time compared to maximum permissible arcing time of CB is defined as a CB failure to clear mode. Measuring CB arcing time is not easy because there is no control on the mechanical opening and closing instants of CB contacts. Nevertheless, there is a correlation between the spectral energy densities of CB arcing voltages and arcing times of CB. This correlation is used by calculating the spectral energy densities of the instantaneous system voltage and the instantaneous CB voltage across its terminals utilizing discrete Fourier transform for two periods of the system frequency. The difference between the spectral energy densities at the fundamental frequency is defined as a criterion for identifying a failure to clear mode. Whenever this criterion exceeds a predefined trip level, it indicates the occurrence of a failure to clear mode. In this situation, a trip signal is initiated for adjacent CBs to isolate the faulted CB and the fault. The results obtained from computer simulations and measurements show that the algorithm discriminates between normal and abnormal arcing conditions of CB.

Role of apoptosis repressor with caspase recruitment domain (ARC) in cancer.

Apoptosis repressor with caspase recruitment domain (ARC) is a potent inhibitor of apoptosis. Under physiological conditions, ARC is abundantly expressed in terminally differentiated cells, including cardiomyocytes, skeletal muscles and neurons. ARC serves a key role in determining cell fate, and abnormal ARC expression has been demonstrated to be associated with abnormal cell growth. Previous studies have revealed that ARC was upregulated in several different types of solid tumor, where it suppressed tumor cell apoptosis. Furthermore, the increased expression levels of ARC in cancer cells contributed to the development of therapeutic resistance and adverse clinical outcomes in patients with leukemia. However, the exact role of ARC, as well as the underlying molecular mechanisms involved, remain poorly understood. The present review summarizes the characteristics of ARC and its cytoprotective role under different conditions and describes the potential ARC as a new target for cancer therapy.

A new failure protection algorithm for circuit breakers using the power loss ofswitching arc incidents

The principal function of circuit breakers (CBs) is to isolate a portion of the power network from the rest of it in a timely manner following an opening command. Any failure in the opening operation of CBs, especially following a fault condition, will almost certainly result in a catastrophic event. Therefore, the issue of failure detection of CBs is essential and has a vital role in power system protection. This paper presents a novel power-based algorithm for failure detection of CBs. The power loss of CBs due to an arcing event increases as the arcing time gets longer. The arcing time of CBs increases with defective operations originating from any failure or malfunction for different reasons. The proposed method uses the power difference between the input and output terminals of CBs to calculate the power loss due to an arcing event, which can then be used to estimate the arcing energy. A trip signal is initiated whenever the estimated arcing energy for a single opening operation reaches a predefined trip level, which shows a failure in CB operation. This predefined trip value is related to the integration of the maximum power capacity of the CB during an opening operation time. Computer simulation studies conducted to analyze the performance of the proposed technique demonstrate that the algorithm is capable of discriminating between normal and abnormal arcing energies and thus identifying malfunctions or failures in the opening operations of CBs.

Research on Abnormal Identification Technology of Circuit Breaker extinction based on wavelet analysis

Circuit breaker is the actuator of power network fault removal and operation mode conversion. If the circuit breaker itself cannot complete the breaking operation, it may cause the accident impact range to expand, or even cause more serious chain failure. The fault phase current is decomposed based on wavelet analysis and Fourier transform, and the unstructured recorded wave data is converted into structured fault characteristic quantity to realize the analysis of current mutation characteristics. The high frequency characteristic singular value at the occurrence of arc is obtained by wavelet transform, which provides the key characteristic quantity for the identification of abnormal arc extinguishing performance of circuit breaker and realizes the identification of abnormal arc extinguishing state of circuit breaker. Issue an alarm before abnormal expansion of circuit breaker or adverse impact, remind relevant personnel to timely check and deal with defects, reduce the occurrence of abnormal tripping circuit breaker phenomenon.

Failure Detection of On-Load Tap-Changers Using a New Power-Based Algorithm

This paper presents a novel arcing power-based algorithm to identify failures in operations of on-load tap-changers (OLTCs). An OLTC is the solely moving part of power transformers and thus highly prone to failure. Most of the OLTC defects are originated from abnormal arcing times leading to abnormal arcing energies. The proposed algorithm utilizes the power difference between the input and output terminals of transformer to estimate the OLTC arcing power. The integration of arcing power for a tap-changing operation results in an arcing energy. This arcing energy is estimated for each operation and used as an indication of OLTC failure. By this definition, whenever the estimated arcing energy exceeds a predefined value for a tap-changing event, it shows a failure in OLTC operation. The outcomes obtained from extensive simulation studies for different internal failures and external faults prove that any malfunction or failure in the operation of OLTC can be detected by the proposed method in a timely manner.

A New Entropy Bi-Cepstrum Based-Method for DC Motor Brush Abnormality Recognition

Abnormal arcs in dc motors are often associated with various potential failures or operational defaults. Although they may not directly led to motor breakdown, they can be causes to faults, further damages, and fire hazard. There can be arcs between brushes and rotors when motor running under normal condition, known as normal arcs. However, abnormal arcs, which are difficult to be visually distinguished from normal arcs, occur when there is loosen or contamination of brushes. Therefore, detecting the existence and identifying the type of unusual arcs can be applied as an effective method for brush condition monitoring. This paper presents a detection strategy for abnormality in brush based on the online electromagnetic field (EMF) analysis with advanced feature extraction techniques. The techniques aim at finding the unusual changes in EMF to identify abnormal arc among normal ones. Entropy bi-cepstrum applied as feature extraction method is an inverse spectrum of cumulant. Bi-cepstrum is insensitive to noise, and entropy reflects the complexity of the target signal. In the experiment, three typical types of unusual arcs occurring in brush area are successfully identified, and the result shows the accuracy as high as 91.4%. The new strategy with algorithms can serve as a very useful tool for abnormality recognition of the motor brush.

Machining Performance of Slotted-Electrical Discharge Diamond Face Grinding of Al/SiC/Gr Composite

Electrical discharge diamond grinding (EDDG) is a well-known process for machining of electrically conductive hard and brittle materials. Even though, EDDG process suffers with several drawbacks such as loss of diamond particles without wear, high wheel wear, accumulation of debris into gap, abnormal arcing, etc. The aim of this study is to minimize the drawbacks of EDDG process with an alternative application of spark erosion and abrasive abrasion actions. Such developed process is knows as slotted-electrical discharge diamond grinding (S-EDDG) process. The performance of developed process was tested on face grinding mode of the S-EDDG during machining of the aluminum–silicon carbide–graphite (Al/SiC/Gr) workpiece. The role of current, pulse on-time, pulse off-time, wheel rotation per minute (RPM), and abrasive grit number has been investigated on material removal rate (MRR) and average surface roughness (Ra). It has been observed that higher wheel RPM gives higher MRR with better surface finish due to increase in flushing efficiency.

접촉 불량에 의한 불꽃 및 직렬아크의 검출 기법에 관한 연구

본 연구는 저압 선로의 접촉 부분에서 발생할 수 있는 접촉 불량과 그 부분의 진동이 결합될 경우 발생될 수 있는 불꽃 및 직렬 아크를 검출할 수 있는 방법에 대한 것이다. 일반적으로 전기화재의 원인은 과전류, 단락, 접촉불량 등 여러 가지가 있을 수 있다. 이 중 과전류 및 단락 등은 선로에 흐르는 순간 전류량을 검출하여 감지할 수 있으나, 접촉불량은 전압, 전류값의 초과분 및 파형의 왜곡으로는 검출하기가 어려운 점이 있다. 따라서 본 논문에서는 퍼지논리 및 다차원 기법을 이용하여 최적의 아크 판단 기법을 연구하고, 아크 검출 및 검증을 위한 모의실험과 제어기 실험 및 부하실험을 실시하였다. 그 결과 제어기 및 검출 알고리즘이 여러 가지 부하와 상관없이 정상적인 부하의 파형과 아크 발생시의 파형을 구분하여 성공적으로 직렬아크를 검출하였다. This study is on the method of the detection for flame and series arc which can be happened at poor contact point added a vibration in part of contact point of low voltage line. In general, the causes of electric fire are over current, short circuit, poor contact, ect. The over-current or short circuit among those causes is detected by measuring a instant current value, but poor contact is difficult to detect by measuring a excessive value of the voltage and current and a distortion of waveforms. And therefore, in this paper, it is studied on the optimal technique of the arc judgement using fuzzy logic and MDET (Multi Dimension Estimation Technique). And it carries out the simulation for arc detection and the experiment for controller and load test. In result, the controller and detection algoristhm, is classified with normal wave and abnormal arc wave without relation with each loads and so the controller can detect a series arc successfully.

A Study of the Mechanism of Electrical Discharge Machining of Particle Reinforced Metal Matrix Composites with Concavo-Convex Electrode

A new concavo-convex electrode has been designed and employed. And an analysis of the electrical discharge machining (EDM) mechanism of a particulate reinforced metal matrix composite with this new electrode was conducted in this study. It was found that EDM with this new electrode can accelerate the debris discharge during machining so that it has a higher MRR compared to the case where a normal electrode was employed. Moreover, by studying the surface craters, it could confirm that discharge craters tend to connect together for the normal electrode. This indicates an abnormal arcing condition. Thus, the wire electrode was easy to be broken. While for the new electrode, separated craters were observed on the machined surface. This means a stable processing condition. The experiment results reveal the processing mechanism of EDM electrical discharge machining of MMCs by employing this new electrode.

A Case of Central Nervous System Myelomatosis with Complex Chromosome Aberrations

Involvement of the central nervous system is very uncommon in multiple myeloma, observed in approximately 1% of the multiple myeloma patients. We report a case of central nervous system myelomatosis with complex chromosome aberrations in a 62-yr-old female patient, who had previously been diagnosed as multiple myeloma. Fluorescent in situ hybridization revealed 13q deletion, p53 gene deletion and IGH/FGFR3 rearrangement and chromosomal study showed complex chromosome aberrations. After four cycles of chemotherapy, the patient was admitted to the hematology department with severe headache. Plasma cells were found in the cerebrospinal fluid (CSF), and CSF immunoelectrophoresis revealed abnormal precipitin arcs against anti-IgG and anti-lambda antisera. She was given systemic chemotherapy and eight courses of intrathecal chemotherapy, which cleared plasma cells in the CSF. Two months later, she was given autologous stem cell transplantation. Three months after stem cell transplantation, central nervous system myelomatosis progressed to plasma cell leukemia and two months later, the patient expired.

頸部術後にＣＲＰＳ（Ｃｏｍｐｌｅｘ Ｒｅｇｉｏｎａｌ Ｐａｉｎ Ｓｙｎｄｒｏｍｅ）ｔｙｐｅ Ｉを生じた１例

We report on a case of complex regional pain syndrome (CRPS) type I. A 27-year-old woman underwent lymph node biopsy of the neck to confirm a diagnosis of histiocytic necrotizing lymphadenitis. Four days after the biopsy, she complained of hyperpathia and limited range of motion on the thumb, forefinger and middle finger of the right hand. She was diagnosed as having CRPS with thermography and treated with glucocorticoid, mecobalamin, and nonsteroidal anti-inflammatory drugs (NSAIDs). The symptoms disappeared within a month and no relapse was seen. CRPS is a disorder of the extremities that is characterized by pain, swelling, limited range of motion, vasomotor instability, skin changes, and patchy bone demineralization. It frequently begins after an injury, surgery, or vascular events, e.g., myocardial infarction or stroke. Tonsillectomy and free forearm flap can cause CRPS. Two types of CRPS have been reported: type I corresponds to patients with CRPS without a definable nerve lesion. Type II which was formerly termed causalgia refers to cases with a definable nerve lesion. The pathogenesis of CRPS is still unclear. CRPS might be caused by the formation of an abnormal reflex arc between the sympathetic nervous system and peripheral vascular components after a causative event. The diagnosis of CRPS is difficult, however, symptoms such as characteristic pain including allodynia and hyperpathia, and altered skin temperature are helpful. Autonomic testing such as thermography and bone scintigraphy are also useful. Prevention and early diagnois are important to treat CRPS. Therefore careful examination and a good understanding of CRPS are recommended.

Improvement of Machining Stability of Micro EDM Using Electrostatic Induction Feeding Method

This paper describes the machining characteristics of the electrostatic induction feeding method. With the conventional relaxation pulse generator normally used in micro electrical discharge machining, since the gap voltage begins rising after the end of the previous discharge, it is difficult to keep the minimum necessary discharge interval between pulse discharges to recover the dielectric breakdown strength of the gap. Thus, localized discharge and abnormal arc easily occur, resulting in machining instability. Moreover, since discharge even occurs before the capacitor is fully charged due to the long time constant of the RC circuit, it is difficult to obtain uniform discharge energy per pulse. In contrast, with the electrostatic induction feeding method, since only a single discharge occurs for each cycle of the periodic pulse voltage, the discharge gap can be cooled regularly during the discharge interval, resulting in stable machining. Therefore, machining characteristics of the electrostatic induction feeding method were investigated using the machining system newly developed for micro-hole drilling. Machining results show that the machining speed of this pulse generator is higher than that of the relaxation pulse generator in micro-hole drilling, especially when rotation speed of the tool electrode is low.

Achieving high accuracy and high removal rate in micro-EDM by electrostatic induction feeding method

With conventional relaxation pulse generators used in micro-electrical discharge machining, due to the difficulty in keeping the minimum necessary discharge interval between pulse discharges, localized discharge and abnormal arc occur frequently. In contrast, with the newly developed electrostatic induction feeding method, only a single discharge occurs for each cycle of the periodic pulse voltage. As this realizes sufficient cooling of the discharge gap between pulses, thermal stress on the machined surface is less and duty factors can be increased, resulting in higher accuracy and machining speed compared to the relaxation pulse generator.

Occurrence of arc interaction in tandem pulsed gas metal arc welding

In the tandem pulsed gas metal arc welding, the occurrence of arc interruption by the electromagnetic interaction between the two adjacent arcs becomes a problem. In order to clarify this problem, effects of interwire distance and Ar–CO2 gas mixture ratio on an abnormal arc voltage and arc interruption are investigated. The abnormal arc voltage and the arc interruption frequently occur with pulse peak currents which are supplied alternately to two wires. In addition, both phenomena occur in trailing arc which is located on molten pool at base current duration remarkably. There is most number of abnormal arc voltage and arc interruption times in trailing when the interwire distance is 10 mm, because a deflected length of trailing arc by the electromagnetic interaction becomes the longest. Moreover, the CO2 mixture ratio in shielded gas affects the occurrence of abnormal arc voltage and arc interruption. The abnormal arc voltage and arc interruption do not occur when CO2 gas mixture ratio is equal to or less than 5%. However, number of abnormal arc voltage and arc interruption times increase rapidly with increasing CO2 gas mixture ratio when CO2 gas mixture ratio is over 10%.

Observations of the phenomenon of abnormal arc voltage occurring in pulsed metal inert gas welding of aluminium alloy

At the time of arc reignition after short circuiting during electrode positive polarity, cathode spots are newly formed in the centre of the weld pool surface, where oxides scarcely exist. The work function of the cathode surface increases and the cathode spots concentrate because of the lack of sufficient oxides, leading to an increase in the potential gradient across the cathode fall space and the adjoining contraction space. Consequently, the arc voltage becomes abnormally high in spite of the short arc length. Moreover, when electrode polarity is switched from positive to negative immediately after a droplet has detached from the wire tip, cathode spots are newly formed on the surface of the molten metal remaining at the wire tip, where little oxide exists, leading to an abnormal increase in arc voltage as well. Therefore, the change in arc voltage does not necessarily indicate a fluctuation in the arc length.