GB889159A - Improvements in or relating to dielectric heating apparatus - Google Patents

Abstract

889,159. Dielectric heating ovens. RADYNE Ltd. Nov. 30, 1960 [Feb. 3, 1960], No. 3885/60. Class 39(3) Dielectric heating apparatus comprises at least two ovens, through which passes a conveyer band for carrying the material to be heated, and control means serving to initiate or increase the heating in a subsequent oven and to prevent or restrict further increase in the power drawn by a given oven when this power reaches a predetermined value. In the arrangement shown moist biscuits of varying thicknesses are carried by a conveyer band 2 through a conventional baking oven 4, employing for example hot air or radiation heating, and through three dielectric heating ovens 6, 8 and 10, each having a work electrode 12 and a generator 14. Ovens 6 and 8 are provided with control devices 16 and 18 respectively, each including a motor controlled by the cathode current of the oscillator valve of the associated generator 14. The generator 14 of the first oven 6 may be brought into operation by a device which measures the moisture content or the thickness of the biscuits. If the biscuits become wetter or thicker more power is drawn from the first generator 14 and the control device 16 raises the work electrode 12 of the oven 6 when the power reaches a given limit. In rising, the electrode 12 operates a switch to energize the generator 14 of the second, oven 8. The generator 14 of the third oven 10 is brought into operation in the same way by control device 18. The control devices 16 and 18 operate in a similar manner to lower the electrode 12 of ovens 6 and 8 and to switch off the generators 14 of ovens 8 and 10 on a decrease in thickness or moisture content of the biscuits.