Patent GB-190503184-A (GB)
Title: Improvements in Installations for Controlling Electrically Propelled Trains.
Filed: 1905-02-15
Granted: 1906-02-15
Abstract: 3184. Siemens Bros. & Co., and Jenkin, C. F. Feb. 15. Transformers switches.-Relates to the equipment of electric cars propelled by a pair of motors on each car worked by single-phase alternating currents, in which the voltage is varied as described in Specification No. 23,398, A.D. 1901, by current being taken from various parts of the secondary coil of a transformer having its primary supplied from the line, and comprises improvements on the invention described in Specification No. 2864, A.D. 1905, which comprises means for varying the voltage without any intermediate drop and for interlocking the contactors of the secondary winding. By the present invention the mastercontroller can be at once turned into the desired position, when the contactors will close and open one after another in a definite sequence, the rate of which is controlled by a governor switch which opens when the current exceeds a predetermined value. Fig. 2 shows the control circuits and the interlocking arrangement of the contactors x<1> ... x<8>, two of which are employed for each section of the secondary winding g and each pair being joined in parallel ; four train-wires 1 . . . 4 and four steps p<2> . . . p<5> are required on the master-controller. The sections of the secondary winding are switched in circuit with resistances k, l, m, n, which are then short-circuited by contactors x<1>, x<3>, x<5>, x<7>. Assuming the controller turned into the position p<3>, the train-wires 3, 4 being thus supplied with current, a circuit is completed through the contactor x<8> and contacts 38 . . . 32. The contactor x<8> is thus operated, whereby another circuit is established through the contactor x<7>, contact 49, and governor switch f The contactor x<6> then drops and the circuit of the contactor x<7> is through the contacts 28 and 37 . . . 32. This completes a circuit through the train-wire 3 through the contacts 48, 59 and the governor switch f<1>. The contactor x<6> rises and the circuit of x<7> is broken, and it therefore falls, completing the circuit of x<5>, and so on, until the full voltage of the second section of the secondary of the transformer is available. The governor switch f<1> is such that an abnormal rise of current opens the gap 30 and the next contactor following that just closed cannot operate until the current falls. The controller contains a switch d' which opens when the handle is turned backwards, thus insulating the contact m and preventing useless operation of the contactors. Fig. 3 shows an arrangement of contacts which renders it necessary for the controller handle to be moved into the position p<2> before it can be moved forwards again. Fig. 4 shows the application to the arrangement of contactors described in Specification No. 2864, A.D. 1905. The resistance contactors x<9>, x<10> are always supplied with current by a branch from the lead 6. In this case a time-lag switch g<1> is preferably used. If the current becomes excessive, this switch opens a gap 30<a> in the same circuit as the gap 30, giving the governing-switch time to act.