| 摘要 |
647,037. Electric vehicles. GENERAL ELECTRIC CO., Ltd., and TURRALL, J. C. Sept. 15, 1948, No. 24278. [Class 79 (iii)] [Also in Group XXXVII] In electrically driven locomotives of the kind including a compressed air operated pantograph for collecting high voltage electric power from an external supply and a chamber or enclosure containing the main electrical circuits and a motor-generator set which converts the power to a lower voltage and the generator thereof supplies a field winding of the motor of the set, entry by an operator to the chamber being prevented unless the main circuits are disconnected from the external power supply, switching means are provided associated with the field winding and controlled by or in dependence upon the position of the pantograph so that the field winding is disconnected from the generator to prevent the motor generating a dangerous voltage when the pantograph is disconnected from the external power supply. As shown the pantograph 2 can connect on overhead line 1 to the main circuits 4 and the motorgenerator set 5 housed in the chamber 3. The circuit from the generator 7 to the motor field winding 9 includes switching means 10 which takes the form of a contactor controlled by a pneumatic relay. The relay comprises a cylinder 11 having a spring urged piston 12, whose rod 14 carries insulated contact segments 15, 16 co-operating with fixed contacts 17. The cylinder 11 is connected with the pantograph operating cylinder by a passage 18 so that when the pantograph cylinder is exhausted so is the cylinder 11 and the switching means 10 opened. The relay is operated at a slightly lower air pressure than the pantograph to ensure the pantograph is clear of the line 1 before the winding 9 is open circuited. If desired the motor 6 may be earthed by main switching means which earth the main circuits 4 before the operator can enter the chamber 3. |
