| 摘要 |
The insulating support-plate (2) has a spiral groove on top and magnetic focussing inserts (21) beneath. The coil (10) employs bare copper strands laid up, to counter proximity effect, in Litz configuration, the strand diameter not exceeding 0.4mm because of skin effect at e.g. 25 kHz. The coil assembly is placed in a non-ferrous base (5), e.g. of aluminium, enclosed by the hob-plate (3). The spiral, pressed into the slightly under-sized groove, is held secure under a thermally insulating sheet (3a), giving protection against heat radiated from the ferrous cooking vessel (4). Opt. a stranded bare aluminium Litz conductor is used, inter-strand insulation being automatically provided by surface oxidation. |
