| 摘要 |
This reactor ballast is used for controlling a lamp and comprises a core and winding connected in circuit with the lamp and inductively coupled to the core for developing a magnetic field in the core when the winding is traversed by electric current. The core forms a magnetic circuit for the magnetic field comprising two parts in series with each other in the magnetic circuit, one part being of metallic magnetic material and the other being of ferrite material. A control arrangement is provided for varying the temperature of at least a portion of the ferrite part in a predetermined temperature range just below the Curie point of the ferrite material where its relative permeability decreases steeply in response to small temperature increases. This temperature-varying arrangement comprises (a) a heating device in heat-exchange relationship with the ferrite portion and (b) control arrangement for causing the heating device to raise the temperature of the ferrite portion within said predetermined temperature range in response to predetermined system conditions and for causing the temperature of the ferrite portion to decrease within said predetermined range in response to other system conditions, thereby controlling the inductance of the reactor ballast and, as a result, controlling the performance of the lamp.
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