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.

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.

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 sub-circuit. 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 paper 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 research 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.

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