By relating relative overshoots of input current and load voltage for switch-on of the considered electrical circuit by either a relay contact or a SSPC, (2.32) and (2.33) represent a very important result of the investigations. The ‘damping properties' of the SSPC are put into evidence. Input current and load voltage have been plotted for the entire switch-on process in Fig. A.5. The shape of the load voltage for the time interval tL has been obtained by integrating (2.2). Conclusions of Section 2 Due to its current limitation feature and its fast reaction, the SSPC shows a completely different switching behaviour than a mechanical relay contact. Electrical circuits with a very small damping coefficient can be switched on by keeping voltage and current overshoots to a minimum. Particularly equations (2.32) and (2.33) reveal this property. The damping behaviour is improved when the difference between limitation current of the switch and steady state load current is reduced, i.e. when the selectivity is increased. Even a high selectivity (i.e. when the switch is really matched to the load) does not lead to dramatic restrictions regarding sizes of reactive filter elements. Capacitors up to several 100/zF can be charged by a 5 Amp device without tripping. In order to facilitate the matching process between load and SSPC, its limitation current should be adjustable (up to minus 35%). REFERENCES [1] LC3: Application to Voltage Regulation; LC3: O'Sullivan, D. & Weinberg, A., Applications in Power Switching and Protection, Proceedings of the Third ESTeC- Spacecraft Power Conditioning, Seminar Held at Noordwijk, the Netherlands, 21-23 September 1977. [2] Medium Voltage Power Switch (Preliminary specification) Ref: C. SE. MVPS.ST.017 by C. Cazaoulou & F. Fachinetti, CROUZET, 25 rue Jules Vodines, 26027 Valence, Cedex, France.
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