Protection Distance of Surge Protective Devices in Low Voltage Distribution Systems

Protection distance of surge protective devices (SPDs) is an important problem in designing a good location scheme of SPDs in low voltage distribution systems for protecting electrical equipments against over- voltage caused by lightning stroke. The simplified lumped-parameter circuit model and the circuit method were used to study the protection distance problem of SPDs. The analytical solutions of the load voltage and general equations of the protection distance of SPDs under different load conditions were given. Simulation results of examples proved the validity of the proposed analytical method.

Addressing mucosal ulcers during orthodontic treatment:An urgent call for preventive strategies

Mucosal ulcers are a common yet often overlooked complication during orthodontic treatment,significantly impacting patient comfort and compliance.This letter aims to highlight the prevalence,potential causes,and management strategies for mucosal ulcers in orthodontic patients.By reviewing recent literature and clinical observations,we underscore the necessity for proactive measures and tailored interventions to mitigate the incidence and severity of these lesions.Emphasizing the role of patient education and the use of protective devices,we call for a multidisciplinary approach to enhance patient care and treatment outcomes.This discussion is particularly relevant in the context of evolving orthodontic techniques and materials,which necessitate continuous adaptation of clinical practices to ensure patient safety and well-being.

Multi-Scale Design and Optimization of Composite Material Structure for Heavy-Duty Truck Protection Device

In this paper,to present a lightweight-developed front underrun protection device(FUPD)for heavy-duty trucks,plain weave carbon fiber reinforced plastic(CFRP)is used instead of the original high-strength steel.First,the mechanical and structural properties of plain carbon fiber composite anti-collision beams are comparatively analyzed from a multi-scale perspective.For studying the design capability of carbon fiber composite materials,we investigate the effects of TC-33 carbon fiber diameter(D),fiber yarn width(W)and height(H),and fiber yarn density(N)on the front underrun protective beam of carbon fiber compositematerials.Based on the investigation,a material-structure matching strategy suitable for the front underrun protective beam of heavy-duty trucks is proposed.Next,the composite material structure is optimized by applying size optimization and stack sequence optimization methods to obtain the higher performance carbon fiber composite front underrun protection beam of commercial vehicles.The results show that the fiber yarn height(H)has the greatest influence on the protective beam,and theH1matching scheme for the front underrun protective beamwith a carbon fiber composite structure exhibits superior performance.The proposed method achieves a weight reduction of 55.21% while still meeting regulatory requirements,which demonstrates its remarkable weight reduction effect.

Development of the Embedded Protective Device Based on ARM

An embedded protective device for 35kV power line is worked out based on Philips’ LPC2292 ARM MCU. Several aspects such as embedded design technique adopted in the system framework, application of adaptive theory in data acquisition, Board Support Packet (BSP) developing and task dispatching related to operating system are discussed. Both hardware and software framework of the system are given. Advanced hardware platform and software development environment is applied in design of the system, with the advanced co-design technology.

The Automated System of Unified Templates as an Element of Trainability of Microprocessor Relay Protection Devices

The article discusses the possibility of further modernization of the standard microprocessor relay protection of AC overhead system feeders DPA-27.5-TNF, which is operated on the Trans-Baikal Railway by creating an additional automated system of unified templates necessary for the occurrence of “trainability” elements. The templates will be formed via a separate dedicated channel for transmission, processing and storage of the necessary information, not related to the operation of the terminal, with its subsequent visualization at the workplace of the duty personnel of traction substations, together with information from the “GID” software received via another dedicated wired channel. With the help of such a base of unified preset templates, in the future, it will be possible not only to identify the specific causes of each emergency shutdown but also to reduce their number by dynamically adjusting the existing presets of the standard operation algorithm.

Analysis on sports and recreation activity-related eye injuries presenting to the Emergency Department

AIM：To investigate the incidence and general characteristics of sports-related eye injuries in patients visiting the Emergency Department. METHODS： A cross-sectional,multi-center,observational study.Patients with an injured eye who visited the Emergency Department at one of nine hospitals in Korea were enrolled.All data were prospectively collected between March and September 2010 using a questionnaire.Eye injuries that occurred during risky sports were examined by gender and age.Additionally,the rate of open globe injuries that occurred with and without protective eyewear was examined for each activity.Continuous variables were compared using Student＇s t-test and categorical variables were compared using Chi-square test.RESULTS： A total of 446 patients had sports-related eye injuries.Teenagers（10-19 years old） and young adults（20-29 years old） had the most eye injuries.Eye injuries accounted for 0.2% of Emergency Department patients.Baseball was the most common cause of sports-related eye injuries,followed by soccer and hiking.Protective gear was worn by 9.4% of all patients.Patients that were 30-39 years of age had the highest rate of protective gear use,followed by patients that were 40-49 years of age.The proportion of sports-related eye injuries that were open-globe injuries was highest for soccer and hiking.CONCLUSION： Although injuries were most common in patients below the age of 10 years,these patients had the lowest rate of protective eyewear use.Injuries in adults over 40 years of age most commonly occurred during hiking,but the rate of protective eyewear use was low.Young athletes should be educated on and provided with protective eyewear and policies protective gear use should be established.For older adults,eye protection should be encouraged,especially during hiking.

Impact of noise on hearing in the military

Hearing plays a vital role in the performance of a soldier and is important for speech processing. Noise-induced hearing loss is a significant impairment in the military and can affect combat performance. Military personnel are constantly exposed to high levels of noise and it is not surprising that noise induced hearing loss and tinnitus remain the second most prevalent service-connected disabilities. Unfortunately, unlike civilian personnel, military personnel have little option but to remain in noisy environments in order to complete specific tasks and missions. Use of hearing protection devices and follow-up audiological tests have become the mainstay of prevention of noise-induced hearing loss. This review focuses on sources of noise within the military, pathophysiology and management of patients with noise induced hearing loss.

Noise Exposure and Its Auditory Effect on Industrial Workers

This paper analyzes the effect of exposure to noise among industrial workers in Nigeria to discover the level of exposure to noise that causes auditory defects or noise-induced hearing loss (NIHL), this paper primarily covers the evaluation of hearing impairment and its severity on exposure to loud sounds (acoustic trauma) and the role of hearing protective devices for industrial workers for prevention of Noise Induced Hearing Loss (NIHL). The paper also discusses the findings and guides as preventive methods for such industries. A total sample of seventy (70) workers were selected from three (3) manufacturing industries for this study. This study revealed a statistically significant difference in the hearing threshold within the selected industries over the selected period of time relating to the theory of excessive noise present in a given environment tends to affect people or in this case study employees hearing if proper hearing protection isn’t used for prolonged hours or time, the study also surveys the various effect of noise on human health including various steps of noise control in such settings.

Effect of a distal protection device on epicardial blood flow and myocardial perfusion in primary percutaneous coronary intervention

Objective: The beneficial effect of percutaneous coronary intervention (PCI) in patients with acute myocardial infarction (AMI) has been well established, but there is the problem of no-reflow phenomenon which is an adverse prognostic factor in primary PCI. In the present study the effect of a distal protection device (PercuSurge GuardWire; GW) on epicardial blood flow and myocardial perfusion was evaluated. Methods and Results: Patients with AMI were randomly divided into 2 groups, the GW and the control groups. The GW group included 52 patients with AMI who underwent primary PCI with GW protection and the control group included 60 patients who underwent primary PCI without GW protection. Epicardial blood flow in the infarct-related artery (IRA) and myocardial perfusion were evaluated according to the thrombolysis in myocardial infarction (TIMI) flow grade and the myocardial blush grade (MBG). We found TIMI score of 3 was obtained significantly more frequently in the GW group (96%) than in the control group (80%). The MBG score of 3 was obtained also significantly greater in the GW group (65%) than in the control group (33%). Conclusion: Primary PCI with GW protection can significantly improve epicardial blood flow and myocardial perfusion.

Teeming stream protection using an argon shroud during casting of steel ingots

Two kinds of argon shroud protection devices with two different basic structures were designed and investigated. Industrial experiments and numerical simulations were used to examine the protection effect, and the mechanism of air entrapment during the casting of steel ingots was analyzed. The influence of the structure of the argon shroud protection device on the protection effect was investigated. An argon shroud protection device mounted to the nozzle holder on the bottom of the ladle does not provide a good protection effect because air can easily flow into the teeming system and cause reoxidation of molten steel during teeming. By contrast, an argon shroud protection device seated on the top of the central trumpet provides an excellent protection effect, where air has little chance of flowing into the teeming system during casting. The feasibilities of the argon shroud protection devices are discussed.

A Novel Crowbar Impulse Current Circuit for Testing the Switch-Type SPD

A crowbar impulse current circuit for testing the switch-type surge protective device （SPD） is presented. The crowbar circuit consists of a computer control circuit, a trigger voltage pulse generator, a main discharging switch, and a crowbar pseudospark switch. The active trigger technology was studied in the crowbar impulse current circuit. The circuit monitors the main discharging current and generates a trigger signal at a proper time for the crowbar pseudospark switch operation. The trigger characteristics of the main discharge switch and the crowbar pseu- dospark switch were investigated. By monitoring the preset applied capacitor voltage, the gap distance of the main discharging switch could be adjusted to ensure a discharging delay time less than 2 μs. Equipped with a surface ttashover trigger device made of high relative perimittivity dielectric material BaTiO3 （εr = 3460）, the discharge delay time of the crowbar pseudospark switch is less than 85 ns, and the minimum operating voltage is less than 1% of its self-breakdown voltage. With a storage capacitor of 9 μF , an inductor of 18 μH and a crowbar pseudospark switch, a load of 30 mΩ and an applied capacitor voltage of 40 kV, an impulse current waveform of maximum 25 kA was generated with a rise time and time to half peak value of 17.2 μs and 336μs respectively.

Evaluation of the Protégé^(TM) stent in the treatment of carotid artery stenosis with adjunctive use of a filter Embolic Protection Device (PROCAR)-one-month follow-up data on 77 patients

Objective The trial was designed to evaluate the safety and performance of the ev3 Protégé TM stent in the treatment of de novo or re-stenotic common and/or internal carotid artery stenoses with adjunctive use of a CE-marked filter embolic protection device.Methods This study was a prospective multi-center, single-arm trial. Between June and October 2003, 77 patients were enrolled in 8 investigational centers throughout Europe. The primary endpoint was the incidence of Major Neurological Events (MANE) through one month. Other endpoints were the ability to properly place the stent, and primary patency and MANE after six months. Eligible for the study were patients with a de novo or restenotic target lesion located in the common and/or internal carotid artery (>70% stenosis for asymptomatic and >50% stenosis for symptomatic patients). The ev3 Spider (Embolic Protection Filter was used in 75 of 77 cases. Results In 76 out of the 77 patients (99%), the stent could be successfully implanted with a residual stenosis ≤30% as criterion. Of the 74 patients that had a carotid ultrasound at one month follow-up, none had a re-stenosis of the target lesion. There were three MANEs during or immediately after the procedure (3.9%), two were major and one was a minor stroke. There were eight severe complications (9.1%); six of these happened during or immediately after the procedure and were related to the procedure, none was related to the device. They are resolved without sequelae. No deaths have occurred.Conclusions The Protégé stent is safe and performs well in the treatment of carotid artery stenosis. The technical success rate for placement of the Protégé stent as assessed by the residual stenosis post implant was very high and all stents were successfully deployed. The incidence of MANE was comparable with that in other recent carotid stent studies and still lower than standard CEA.

Application of the BASNEF Model in Safety Training in Automobile Manufacturing Plants

After controls,including engineering and management,thefinal way to control noise is to use hearing protection devices.Duetothelack ofastandardized questionnaireregarding investigatingworkers’use of hearing protection devices on the basis of the BASNEF behavioral model,the present study was conducted to investigate the effect of health education based on the BASNEF model on the use of hearing protection devices in workers of an auto-mobile manufacturing plant in Iran.This quasi-experimental and prospective intervention study was performed on 80 workers at an automobile manufacturing plant who are exposed to noise levels above 85 decibels and donot use hearing protection devices.In this study,40 people working in a cast iron foundry were selected as the inter-vention group,and 40 working in aluminum casting were chosen as the control group.Questionnaires were ana-lyzed at the beginning of the intervention and three months after the intervention in the intervention and control groups.There was no significant difference between the intervention and control groups before the intervention.There was a significant difference between the intervention and control groups after the intervention in the area of knowledge.A significant correlation was observed between the intervention and control groups after the inter-vention program in all areas of the BASNEF educational model except behavioral intention.In this study,the effect of educational intervention on the use of hearing protection devices was investigated,and with the educa-tional intervention,it was tried to get help from influential people and enabling factors in education based on the BASNEF model.The results showed that the educational intervention based on the BASNEF model can improve the knowledge of individuals in both the intervention and control groups.

Comprehensive Automation of Microprocessor Protection Relay Terminals Operated on AC Railways

The article discusses the possibility of a potential reduction in the number of operations of microprocessor relay protection of feeders of the contact network of AC railways TsZA-27.5-FKS (FTS) for unknown reasons. Real statistics on the number of microprocessor relay protection operations at the Buryatskaya traction substation are presented, simulation of the real train situation (in accordance with the regime maps of the throughput capacity of the sections of the Trans-Baikal railway) was carried out in the specialized software complex “KORTES”. Based on the results of the analysis of simulation modeling, the process of forming a unified template of settings using neural network technologies is considered, which characterizes only this specific regular train situation. To protect objects in the event of pre-emergency and emergency modes of operation of the traction power supply system, a variant of changing the standard operation algorithm of the TsZA-27.5-FKS (FTS) terminal by introducing additional blocks for calculating the predictive functions of current and voltage has been proposed.

The Protection of Asynchronous Motor

In this paper, the relationship between the protection and control of asynchronous motor and all sorts of protection devices for asynchronous motor are briefly expounded. The protection of motor has mainly developed in three stages： thermal relay, electronic integrated protector, and microcomputer protector. In terms of sampling methods, the protection can be divided into two types： （1） the sampling current detection, which is implemented using a thermal relay with circuit breaker for the thermomagnetic tripping motor protection, and an electronic and solid state relay with circuit breaker and sof~ starter for the thermomagnetic tripping motor protection; （2） the sampling temperature detection, which is to directly detect electromotor winding temperature using bimetallic strip temperature relay, thermal protector, detecting coil, and heat resistance temperature relay. However, the second method is very expensive and difficult to maintain because a motor winding is necessary to directly bury, so it is used only in the cases requiring some frequent operations. Finally, the harmonious cooperation between overload protection device and motor or between overload protection device and short circuit protection device must be considered regardless of the protection device model.

On a Parasitic Bipolar Transistor Action in a Diode ESD Protection Device

In this work, we show that an excessive lattice heating problem can occur in the diode electrostatic discharge (ESD) protection device connected to a VDD bus in the popular diode input protection scheme, which is favorably used in CMOS RF ICs. To figure out the reason for the excessive lattice heating, we construct an equivalent circuit for input human-body model (HBM) test environment of a CMOS chip equipped with the diode protection circuit, and execute mixed-mode transient simulations utilizing a 2-D device simulator. We analyze the simulation results in detail to show out that a parasitic pnp bipolar transistor action relating nearby p+-substrate contacts is responsible for the excessive lattice heating in the diode protection device, which has never been focused before anywhere.

Comparative observation of protective effects of earplug and barrel on auditory organs of guinea pigs exposed to experimental blast underpressure

To explore the protective effects of earplug and barrel on auditory organs of guinea pigs exposed to experimental blast underpressure （BUP）. Methods： The hearing thresholds of the guinea pigs were assessed with auditory brainstem responses （ABR）. The traumatic levels of tympanic membrane and ossicular chain were observed under stereo-microscope. The rate of outer hair cells （OHCs） loss was analyzed using a light microscope. The changes of guinea pigs protected with barrel and earplug were compared with those of the control group without any protection. Results： An important ABR threshold shift of the guinea pigs without any protection was detected from 8h to 14d after being exposed to BUP with a peak ranging from -64.5 kPa to -69.3 kPa （P〈0.01）. The rate of perforation of tympanic membrane reached 87.5 % and that of total OHCs loss was 19.46%± 5.38% at 14d after exposure. The guinea pigs protected with barrel and earplug had lower ABR threshold and total OHCs loss rate compared with the animals without any protection （P 〈0.01 ）. All of the tympanic membrane and ossicular chain of the protected animals maintained their integrities. Meanwhile, the guinea pigs protected with the barrel had lower ABR threshold and total OHCs loss rate than those with earplug （ P 〈 0.01 ）. Conclusions. The earplug and barrel have protective effects against BUP-induced trauma on auditory organs of the guinea pigs and the protective effects of barrel are better than those of earplug.

Transient stability enhancement of DC-connected DFIG and its converter system using fault protective device

Transient stability of doubly-fed induction generators(DFIGs)is a major concern in both AC and DC grids,and DFIGs must stay connected for a time during grid faults according to the power grid requirements.For this purpose,this work proposes an overcurrent and overvoltage protective device(OCV-PD)to ensure that DCbased DFIG system can stay connected and operate well during the faults.Compared with a series dynamic braking resistor(SDBR),two aspects are improved.First,a twolevel control strategy and DC inductor circuit are used to ensure that the OCV-PD can limit the current impulse to protect DFIG system during an overcurrent fault.Second,the OCV-PD can protect system from overvoltage fault which a SDBR cannot do.Simulation results verify itsvalidity and feasibility,finding that for overcurrent protection the OCV-PD outperforms a SDBR with an average decreased index of 3.29%,and for overvoltage protection it achieves an average index of 1.02%.

Programmable protective device for LV distribution system protection

High quality electric power supply is the prime goal in the modern power systems around the world.One of the main ways to achieve this is the protection of the system which needs to be fast,reliable and cost effective.The objective of this paper is to provide protection of equipments in low voltage(LV)distribution system and thereafter to avoid their failure due to abnormal operating conditions.The proposed device provides protection for industrial,commercial and residential equipments by monitoring under voltage,over voltage and over current conditions using microcontroller,transistor and other discrete components.The microcontroller is the heart of this protective device which performs the major control of the device.The designed circuit can withstand the loads and the set voltage range so as to supply the connected load for any voltage variation between 220 and 240 Volts.It can be used to protect loads such as refrigerator,TV,VCR/DVD player etc.against undesirable over and under voltage conditions as well as surges caused due to sudden failure of power supply mains.This device can also be used directly as standalone equipment between the supply mains and the load.The over/under voltage and over current cut-off with time delay provides over/under-voltage and over current protection and also protection against any transients.

Fracture of a cerebral protection device wire in carotid artery stenting： an unexpected complication

There are very few reports concerning the failure of devices used in carotid artery stenting. Here we report a fracture of the distal part of the guiding wire of a cerebral protection device during carotid artery stenting for management of a restenotic lesion after carotid endarterectomy.