A study on stabilization of operation time for hydraulic operating circuit breaker (Stability of hydraulic operation stabilizing system holding constant high pressure)

Circuit breakers for overcurrent protection of semiconductor converters limit the duration and amplitude of the overcurrent at such a level that its thermal effect does not exceed the maximum allowable thermal protection index of the protected semiconductor device. The limitation of the thermal action of the short-circuit current is achieved by reducing the operation time of the circuit breaker. The design of the circuit breaker is changed in such a way that instead of the basic electromagnetic release is used an induction-dynamic release, which consists of an inductor with a ferromagnetic core and a rotary armature in the form of a copper disk. The electrodynamic force producing by the induction-dynamic release for quick operation is determined by the coefficient of mutual inductance of the inductor coil and the armature. Using of a ferromagnetic core entailed an increase in the coefficient of mutual inductance of the coil and armature, therefore, an increase in the electrodynamic force producing by the release, and a decrease in own tripping time of the circuit breaker. On a prototype, an experimental study of the proper operation time of the release was carried out at various values of the electrical parameters of the capacitor bank of the inductor power supply, the winding parameters of the inductor coil and the disk dimensions. The research results have proved both a decrease in the tripping time of the circuit breaker while conserving the energy of the capacitor bank of the inductor, and a decrease in the required energy of the capacitor bank to power the inductor while maintaining the minimum tripping time of the circuit breaker. Reducing the energy of the capacitor bank of the inductor made it possible to reduce the capacity and voltage of the capacitor bank of the supply of the release, and, consequently, its dimensions.

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A Procedure for Determining the Safe Operation Time of Equipment and Pipelines Based on Nondestructive Testing Results

Vestnik MEI ◽

10.24160/1993-6982-2020-6-11-17 ◽

2020 ◽

Vol 6 (6) ◽

pp. 11-17

Author(s):

Dmitriy A. Kuz'min ◽

◽

Aleksandr Yu. Kuz'michevskiy ◽

Artem E. Gusarov ◽

◽

...

Keyword(s):

High Pressure ◽

Wall Thickness ◽

Nuclear Power ◽

Power Plants ◽

Nuclear Power Plants ◽

Operation Time ◽

Safe Operation ◽

Accelerated Corrosion ◽

Equipment And Pipelines ◽

Flow Accelerated Corrosion

The reliability of nuclear power plants (NPPs) has an influence on power generation safety and stability. The reliability of NPP equipment and pipelines (E&P), and the frequency of in-service inspections are directly linked with damage mechanisms and their development rates. Flow accelerated corrosion (FAC) is one of significant factors causing damages to E&P because these components experience the influence of high pressure, temperature, and high flow velocity of the inner medium. The majority of feed and steam path components made of pearlitic steels are prone to this kind of wear. The tube elements used in the coils of high pressure heaters (HPH) operating in the secondary coolant circuit of nuclear power plants equipped with a VVER-1000 reactor plant were taken as the subject of the study. The time dependences of changes in the wall thickness in HPH tube elements are studied proceeding from an analysis of statistical data of in-service nondestructive tests. A method for determining the initial state of the E&P metal wall thickness before the commencement of operation is proposed. The article presents a procedure for predicting the distribution of examined objects' wall thicknesses at different times of operation with determining the occurrence probability of damages caused by flow accelerated corrosion to calculate the time of safe operation until reaching a critical state. A function that determines the boundary of permissible values of the HPH wall thickness distributions is obtained, and it is shown that the intervals of in-service inspections can be increased from 6 years (the actual frequency of inspections) to 9 years, and the next in-service inspection is recommended to be carried out after 7.5 years of operation. A method for determining the existence of FAC-induced local thinning in the examined object has been developed. The developed approaches and obtained study results can be adapted for any pipelines prone to wall thinning to determine the frequency of in-service inspections (including an express analysis based on the results of a single nondestructive in-service test), the safe operation time, and quantitative assessment of the critical value reaching probability.

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Development of 72kV High Pressure Air-insulated GIS with Vacuum Circuit Breaker

IEEJ Transactions on Power and Energy ◽

10.1541/ieejpes.125.1270 ◽

2005 ◽

Vol 125 (12) ◽

pp. 1270-1277 ◽

Cited By ~ 7

Author(s):

Toshiaki Rokunohe ◽

Yoshitaka Yagihashi ◽

Fumihiro Endo ◽

Kenji Aoyagi ◽

Hitoshi Saitoh ◽

...

Keyword(s):

High Pressure ◽

Circuit Breaker ◽

Vacuum Circuit Breaker

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A study on stabilization of operation time for hydraulic operating circuit breaker (Investigation of synchronous / sequential operation system of two high speed hydraulic operating devices)

Transactions of the JSME (in Japanese) ◽

10.1299/transjsme.15-00539 ◽

2016 ◽

Vol 82 (838) ◽

pp. 15-00539-15-00539 ◽

Cited By ~ 1

Author(s):

Tohru YAMASHITA ◽

Yoshiki HIRANO ◽

Nobuya NAKAJIMA ◽

Tsutomu SUGIYAMA ◽

Toshiaki YOSHIZUMI

Keyword(s):

High Speed ◽

Circuit Breaker ◽

Operation Time ◽

Operation System

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Quantitative predictions of cavitation presence and erosion-prone locations in a high-pressure cavitation test rig

Journal of Fluid Mechanics ◽

10.1017/jfm.2017.156 ◽

2017 ◽

Vol 819 ◽

pp. 21-57 ◽

Cited By ~ 16

Author(s):

Phoevos Koukouvinis ◽

Nicholas Mitroglou ◽

Manolis Gavaises ◽

Massimo Lorenzi ◽

Maurizio Santini

Keyword(s):

High Pressure ◽

High Speed ◽

Transient Flow ◽

Mass Transfer Rate ◽

Operation Time ◽

Working Fluid ◽

Experimental Investigations ◽

Micro Ct ◽

Mixture Phase ◽

Cavity Shedding

Experiments and numerical simulations of cavitating flow inside a single-orifice nozzle are presented. The orifice is part of a closed flow circuit, with diesel fuel as the working fluid, designed to replicate the main flow pattern observed in high-pressure diesel injector nozzles. The focus of the present investigation is on cavitation structures appearing inside the orifice, their interaction with turbulence and the induced material erosion. Experimental investigations include high-speed shadowgraphy visualization, X-ray micro-computed tomography (micro-CT) of time-averaged volumetric cavitation distribution inside the orifice as well as pressure and flow rate measurements. The highly transient flow features that are taking place, such as cavity shedding, collapse and vortex cavitation (also known as ‘string cavitation’), have become evident from high-speed images. Additionally, micro-CT enabled the reconstruction of the orifice surface, which provided locations of cavitation erosion sites developed after sufficient operation time. The measurements are used to validate the presented numerical model, which is based on the numerical solution of the Navier–Stokes equation, taking into account compressibility of both the liquid and liquid–vapour mixture. Phase change is accounted for with a newly developed mass transfer rate model, capable of accurately predicting the collapse of vaporous structures. Turbulence is modelled using detached eddy simulation and unsteady features such as cavitating vortices and cavity shedding are observed and discussed. The numerical results show agreement within validation uncertainty with the obtained measurements.

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Design of Intelligent Fast Switch Controller Based on CPLD

MATEC Web of Conferences ◽

10.1051/matecconf/201823204010 ◽

2018 ◽

Vol 232 ◽

pp. 04010

Author(s):

Saifei Liu ◽

Xiaochun Ma ◽

Ruizheng Ni

Keyword(s):

High Speed ◽

Complex Structure ◽

Circuit Breaker ◽

Operation Time ◽

State Monitoring ◽

Capacitor Discharge ◽

Technical Performance ◽

Control Command ◽

Electronic Controller ◽

Hardware Circuit

In view of the large volume, complex structure and many transmission links of the current circuit breaker operating mechanism, a new type of electromagnetic actuator and electronic controller are used to shorten the operation time. This paper introduces the hardware and software design of an intelligent fast switching controller based on CPLD. The hardware circuit design of the controller is mainly described, including power supply conversion and charging voltage monitoring, switch state monitoring, control command monitoring, relay output, LED indicator and split switch driving module. The optocoupler isolation is realized between input and output, and the thyristor module is used to drive the capacitor discharge. The feasibility of the design circuit is verified by the actual sampling waveform, which has the advantages of high-speed operation, intelligent control, high technical performance and reliable operation.

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Separation of Diethylbenzene Isomers on Silicalite in the Presence of High Pressure Carbon Dioxide and Propane

Adsorption Science & Technology ◽

10.1177/026361749100800405 ◽

1991 ◽

Vol 8 (4) ◽

pp. 226-234 ◽

Cited By ~ 1

Author(s):

Chung-Sang Tan ◽

Chen-Lung Liao ◽

Shiaw-Tseh Chiang

Keyword(s):

Carbon Dioxide ◽

Experimental Study ◽

High Pressure ◽

Retention Time ◽

Operating Temperature ◽

Operation Time ◽

Production Plant ◽

Mean Retention Time ◽

The Mean ◽

Time Required

An experimental study of the separation of m- and p-diethylbenzene (DEB) from a mixture containing the weight composition 66.7% m-DEB and 33.3% p-DEB on silicalite has been undertaken using high-pressure carbon dioxide and propane. The high-pressure gases functioned both as a carrier and a desorbent. The results show that the most appropriate operating combinations for obtaining 100% recovery of DEB isomer with a purity of over 99% and the smallest mean retention time for m-DEB was achieved by utilizing CO2 and propane at 34.0 atm, 363 K and 30 cm3/min, and at 6.8 atm, 443 K and 15 cm3/min, respectively. With these various combinations, the mean retention time of m-DEB was 149.7 min and 84.4 min using CO2 and propane, respectively. Accommodation to the operating temperature in the DEB production plant, and taking account of the compression costs and the operation time required, suggests the use of propane to achieve separation.

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