Switching Arc Energy Limitation Approach for LV Circuit Breakers

This paper presents an experimentally verified approach to deriving switching arc energy limitations for low-voltage (LV) circuit breakers (CBs). Air-insulated contactors equipped with additional vacuum-insulated (VI) arcing contacts were tested for AC and DC current interruption efficiency, respectively. In the study, the contact arrangements of reed relay VI contact switches of low current breaking capacity combined with air-insulated contactors were examined. Tests were performed on selected LV CBs inductively loaded for LV power network rated voltages. A comparative analysis of the arc energy resulting from various arc time durations recorded during the switching-off operation was performed. Using a variety of either basic CB air-insulated contact systems or combined contact systems, a practical assessment of the proposed idea for enhancing the arc quenching efficiency was undertaken. As a result of the implementation of the proposed idea, the arc burning duration time was indicated as being hundreds of times shorter. In most cases, a complete arc reduction was achieved. Moreover, the resulting arc energy dissipation during the breaking operation was substantially minimized. Consequently, a significant increase in the total current breaking capacity of the tested CBs was achieved.

ELECTRONIC FUSE USING RESETTABLE POLY FUSE FOR OVER CURRENT PROTECTION

This paper presents a new technique to deal with the high load currents or fluctuating currents using poly fuse as its major component. Poly fuse is a resettable fuse which goes on increasing its resistance, blocking the excess current until the current is back to normal. Once the current is under normal conditions, the resistance stabilizes and the path between supply and load is reconnected. The proposed work also uses a reed relay which breaks the path exactly at the specified rating, allowing a fast switch. The combination of poly fuse and reed relay provides more efficient outputs as compared to traditional circuit breakers. The fast-switching action, accurate results and the smaller size makes poly fuse more suitable for most of the power devices.

The Study of a Physico-Mathematical Model of the Acceleration of Storage Life Tests of Electrical and Electronic Equipment

The article proposes a solution to the problem of the variety of physico-mathematical models of EEE-storage life test acceleration by implementing a method based on the analysis of the results of accelerated tests in different modes. The objects of the study are reed relays. The article presents the main physico-mathematical models used for calculating the acceleration factor when simulating storage, as well as sets forth a description of a method for comparing these models. According to this method, the product is tested in various modes and, in accordance with the procedure for accelerated storage life testing based on the prediction of parameter time-dependent degradation, the storage period is estimated. Then, for each model, the storage period estimate is obtained for normal climatic conditions together with the standard deviation. The model with the least standard deviation is considered to be the most suitable for the tested type of product. The physico-mathematical models of the acceleration of reed relay failure mechanisms during storage were studied with the help of this technique; the most suitable is the reverse exponential model.

DEVELOPMENT OF A NEW GENERATION OF MAGNETIC CONTACT BASED ON HALL-EFFECT SENSOR

This paper describes the development of a new generation of magnetic contact. The development of this new generation of the magnetic contact is a part of the research activity of the security engineering laboratory. The new generation of magnetic contact is based on the Hall-Effect Sensor and microcontroller unit. Older magnetic contacts use a simple reed relay with only two states – normally closed or normally opened. The combination of the Hall-Effect Sensor and microcontroller unit provides advanced possibilities such as a programmable level of magnetic field sensitivity, adding different communication modules, programmable inputs/outputs etc. The results of this paper explain proposal of the new generation of magnetic contact, which can be used not only as a part of intruder alarm systems but also as a part of smart homes and other autonomous systems. The content of the paper can be used for even deeper research and by security systems developers as well.

Analysis of Magnetic Field in Dry-Reed Relay Application Circuit

To the problem of multiple dry-reed relays electromagnetic interference in application circuits, we present an effective method to reduce the electromagnetic interference in this paper. The method is alternating permutation matrix of dry-reed relays. The paper describes the cause of electromagnetic interference of dry-reed relays. Using the offset of electric polarity alternation principle, we put forward the method for reducing electromagnetic interference. The method is applied to a multi-functional physiotherapy instrument. By experiments, experimental result shows that the degree of electromagnetic interference is reduced along with the increase in the number of dry-reed relays.

Electrolytic Recovery of Nickel from Spent Electroless Nickel Bath Solution

Plating industry is one of the largest polluting small scale industries and nickel plating is among the important surface finishing process in this industry. The waste generated during this operation contains toxic nickel. Nickel removal and recovery is of great interest from spent bath for environmental and economic reasons. Spent electroless nickel solution from a reed relay switch manufacturing industry situated in Chennai was taken for electrolytic recovery of nickel. Electrolytic experiment was carried out with mild steel and gold coated mild steel as cathode and the different parameters such as current density, time, mixing and pH of the solution were varied and recovery and current efficiency was studied. It was noticed that there was an increase in current efficiency up to 5 A/dm2and after that it declines. There is no significant improvement with mixing but with modified cathode there was some improvement. Removal of nickel from the spent electroless nickel bath was 81.81% at 5 A/dm2and pH 4.23. Under this condition, the content of nickel was reduced to 0.94 g/L from 5.16 g/L. with 62.97% current efficiency.