| 摘要 |
PURPOSE:To prevent the dewing and freezing of a collector ring so as to maintain the sliding condition between a brush and the collector ring always favorable by cutting off the exciting circuit connected to brushes at low-speed operation or at nonexciting operation thereby applying heating currents between the opposed brushes of individual collector rings through the collector rings. CONSTITUTION:Changeover switches 21 are all made to the S1 sides in the figure at ordinary exciting operation, whereby excitation is made as in the past with a power source 15 for excitation as a power source. Moreover, at nonexcitation when the temperature drop of the collector rings 7 and 8 are easy to occur, the changeover switches 21 are all made to the S2 sides in the figure, and as an electronic circuit, each collector ring 7 and 8 is independent, and the circuit comprising a power source 18, a brush 16A(17A), a collector ring 7(8), a brush 16B(17B) and a power source 18 for heating is constituted. Therefore, for the collector ring 7, a current is applied between the brushes 16A(17A) and 16B(17B), and by joule heat, temperature difference occurs, and dewing and freezing can be prevented. |
