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The sudden voltage drop may upsurge the current level and trigger the self-protective system to disconnect the wind turbines that are detrimental for grid constancy. A novel structure of a modified switch type fault current limiter (M-STFCL) is proposed that protects the doubly-fed induction generator wind turbine (DFIG-WT) during the symmetrical and asymmetrical grid faults. The M-STFCL is cost-effective and requires little maintenance during operation. The proposed system maintains the rotor current and DC-link voltage below the maximum acceptable limits, thus, fortify the back-back converters. The M-STFCL is tested with both the sliding-mode control (SMC) and proportional-integral (PI) controller and their results are compared. From the simulation results, it is obvious that SMC has edged over the PI controller and demonstrated superior control over the critical parameters. The performance of M-STFCL is also compared with the conventional switch type fault current limiter and the analytical results clearly validate the significance of the proposed system.

Purpose The purpose of this paper is to investigate and minimize the printing-related defects in the surface mount assembly (SMA) process. Design/methodology/approach This paper uses an experimental approach to explore process parameter and printing defects during the SMA process. Increasing printing performance, various practices of solder paste (Ag3.0/Cu0.5/Sn) storage and handling are suggested. Lopsided paste problem is studied by varying squeegee pressure and the results are presented. Unfilled pads problems are observed for ball grid array (BGA) and quad flat package (QFP) which is mitigated by proper force tuning. In this paper, a comparative study is conducted which evaluates the manifestation of printing offset due to low-grade stencil. The input/output (I/O) boards were oxidized when the relative humidity was maintained beyond 70 per cent for more than 8 h. This pad oxidation problem is overcome by proper printed circuit board (PCB) handling procedures. When the unoptimized line is used, the paste wedged in the stencil and influences the performance of the screen printer, for this reason, an optimized line is proposed that minimize the printing defects. Findings The key findings are as follows: in the SMA process, printing quality is directly associated with solder paste quality. Experimentally, it is observed that a considerable variance in solder deposition occurred when the front and rear squeegee have different configurations. High-grade and unsoiled stencil results in superior paste deposition and less distinction. Insufficient solder paste and bridge problems also occur in printing when PCB pads are oxidized. Optimized line resolves solder paste clog issues, associated with stencil’s aperture. The cooling arrangement on the conveyor, after reflow, explicates hot jig problem. Control environmental conditions minimized static charges and printing defects. Originality/value The preceding studies emphasis mostly on the squeegee pressure, while other important parameters are not completely investigated. Moreover, it is very imperative to concurrently measure all parameters while varying the environmental conditions. This study highlights and provides an experimental approach to various PCB printing defects, and a comparative study has been conducted that concurrently measure all process parameters.

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Purpose Low relative humidity (RH) effect surface mount devices in numerous ways. The smaller size (0201) capacitor and resistor start wasting when RH is low. Due to low RH, electrostatic charges built-up on the surface of surface mount devices (SMDs) and component’s reel. The positive charged SMDs stick with the negatively charged reel tape and are wasted. This paper comprehensively explores the environmental effects on 0201 size surface mount devices during mounting process. Different type and size of surface mount devices are tested in low and desired RH to validate the effectiveness of the proposed approach. This paper will also highlight high electrostatic discharge (ESD) due to low RH which can be detrimental for small size surface mount devices. The experimental and graphical illustrations will stipulate the results of success rate for mounting components. The effect on ESD, subsequently varying temperature and humidity will also be analyzed. Design/methodology/approach In this paper, 0201 SDMs will be considered for analysis. The surface mount technology (SMT) plant temperature and humidity has been varied to examine the properties of small size SMDs. Total 5 hours production data are collected from Laptop motherboard production environment. This approach is applicable to all SMT environment. Findings The authors reduced the wastage of 0201 chip size resistor and capacitor. Total 11 components are selected of this size, and there success rate is observed during mounting. These components are first observed in harsh environment where the temperature is first set to 20ºC and RH is set to 25 per cent. The success rate of these components is very low due to component’s wastage. When the plant temperature is set to 25ºC and RH is set to 45 per cent, the success rate of mounting increased up to 100 per cent. A single component placement success rate with respect to RH is observed for one month. The results are shown in Table IV. It can be seen that the success rate is near 100 per cent when RH and temperature is maintained in production environment. To eliminate the ESD build-up in material and equipment in manufacturing environment humidification is a very effective way. When the RH is kept to 45 per cent, the moisture content of the air is a natural conductor and earths any ESD in environment. Originality/value Experimental data have been obtained from Laptop motherboard manufacturing process to validate the effectiveness of proposed approach.