Invention of the transistor in 1947 made a radical change to the path of the development of electronic products and systems. In the mid-1950s, integrated circuits (ICs) started evolving rapidly, creating miniaturized analog, digital and mixed signal circuits. By the 1960s to 1970s, microprocessors, memories and power semiconductors entered the electronic marketplace. During the 1980s and 1990s, power supplies required to power the high-performance digital circuits kept dropping towards 2 V and below. By the year 2000, complex digital and mixed- signal circuits required for portable gadgets were powered by very low dc rails as low as 1 V and sub-1 V. Very large-scale ICs and ultra-large scale ICs proliferated after 2000, integrating millions to billions of sub-micron feature transistors. The ultimate result of this massive progress came with the unique problem of vulnerability of modern electronics to transient surges. A detailed background to this is presented in Chapter 1 of reference [1].

SCASA is a patented technique commercialized as a surge protector device (SPD) that adheres to UL-1449 test standards. Apart from the novel use of supercapacitors, SCASA design incorporates a coupled-inductor wound to a specially selected magnetic material of powdered-iron. In this study, we investigate the limitations of the present design under transient operation and elucidate ways to eliminate them with the use of air-gapped ferrite cores. In modelling the operation under 50 Hz AC and transient conditions, a permeance-based approach is used; in addition, non-ideal characteristics of the transformer core are emphasized and discussed with empirical validations. The experimental work was facilitated using a lightning surge simulator coupled with the 230 V AC utility mains; combinational surge-waveforms (6 kV/3 kA) defined by IEEE C62.41 standards were continuously injected into SPD prototypes during destructive testing. Such procedures substantiate the overall surge-endurance capabilities of the different core types under testing. With regard to optimizations, we validated a 95% depletion of a negative-surge effect that would otherwise pass to the load-end, and another 13–16% reduction of the clamping voltage verified the effectiveness of the methods undertaken. In conclusion, SCASA prototypes that utilized air-gapped cores revealed a greater surge endurance with improved load-end characteristics.

Supercapacitor assisted surge absorber (SCASA) technique is a unique and commercially useful design approach for surge protector devices. SCASA topology is based on the combination of a coupled inductor, which partly acts as a transformer, and a supercapacitor (SC) subcircuit. In developing the first commercial product, the research team had to optimize the selection of the magnetic core, based on empirical approaches and industry price constraints. This article presents a permeance-based design and analytical approach to SCASA, with the topological details of its first successful implementation. While existing SCASA topology performs satisfactorily, this article elucidates design techniques to improve surge absorption by 60% and reduce load clamping by 10% based on high-performance prototypes developed using High-Flux and X-Flux toroids. The test results presented in this research are validated by experimental work carried out in a high-voltage surge laboratory using Noiseken LSS-6230 lightning surge simulator adhering to IEEE C62.41/IEC 61000-4-5 standards. Surge immunity of SCASA prototypes was evaluated using international test procedures of UL-1449 3rd edition standard.

Transient-surge absorption capability of small/low cost supercapacitors (SCs) is already published. SCASA is a patented technique that led to the development of a high performance commercial surge protector which adheres to UL-1449 3rd edition test protocols. The commercial implementation comprises a coupled-inductor, two metal oxide varistors (MOVs) and a SC sub-circuit. This paper presents a permeance based model for the coupled-inductor of SCASA topology in predicting its operation under contrasting voltage conditions. In validating the circuit operation with regard to its surge absorption capability versus 50 Hz AC power transfer, a lightning surge simulator (LSS-6230) was utilized. We discuss this comparison based on the standard IEEE C62.41 surge waveforms up to a maximum of 6.6 kV.

Supercapacitors help building long time constant resistor-capacitor circuits. This property helps them withstand high voltage transient surges and dissipate transient energy in the resistive element of the circuit without exceeding the supercapacitor’s DC voltage rating, which is usually between 2.5 to 4 V. SCASA is a patented technique, which was commercialized within the last five years. Successful implementation of this circuit topology, despite its simplicity, is quite dependent on the selection of the core of the coupled inductor utilized. This paper provides the essential details of the process of selecting the core for the magnetic component required, with a brief comparison of SCASA technique with a traditional surge protector, without any supercapacitors.

Supercapacitor assisted surge absorber (SCASA) is a patented technique developed by the University of Waikato. One noticeable attribute of this design is the inclusion of a coupled-inductor which improves its capability of surge absorption.This paper mainly focuses on investigating the usability of ferrite iron for the core of the coupled-inductor, and attempts to explain how to minimize the effects of a negative voltage peak that arises during SCASA operation. Four ferrite cores with different geometries and material compositions (W-ferrite and J-ferrite) are subjected to 6.6 kV surge hits. Experimental outcomes demanded the need of inserting air-gaps inside these ferrite toroids. High magnetic permeability of ferrite results in a low energy storage capability; this limits their suitability in surge absorption related applications. To overcome the issues of high permeability we modified the cores with thin cuts through the surfaces. Experimental work is facilitated by lightning surge simulators (LSS-6110 and LSS-6230) coupled with the utility main to generate surge waveforms defined by the IEEE C62.41. The analysis of test results encourages us to justify the gapped-core approach, and to further verify, performance of SCASA is empirically compared for both powdered-iron cores and modified ferrite cores using international protocols of UL-1449.