Patent GB-190613287-A (GB)
Title: Improvements in and relating to Systems of Operating Electrically Propelled Vehicles.
Filed: 1906-06-08
Granted: 1907-06-06
Abstract: 13,287. British Thomson-Houston Co., [General Electric Co.]. June 8. Switches.-Relates to a system of operating electric railways wherein the current supplied to the cars is at a high voltage, and consists in reducing the potential by means of an induction motor-generatcr set carried by the cars to a suitable value for the series motors, which are adapted to work at a comparatively low voltage. A separate exciter is provided for the generator, and also means for varying the field strength of the generator and motors during both propelling and braking, in the latter case the generator being driven as a motor for driving the induction motor above synchronism so as to return energy to the line. An overload protective device is also provided. A master-controller K is adapted to govern a controller C, arranged to connect the motors M<1>, M<2> with their resistances R<1> ... R<4> to the armature 1 of the generator a<1>. The controller K also governs the resistance section R<5> ... R<9> of a controller D, which may be included in series with the field winding 2 of the generator a<1> ; the other section r<1>, r<2>, r<3> of the controller D is governed by an auxiliary mastercontroller H. A commutating-switch L co-operates with the controller K to produce either power or braking connexions fo:r the motors. A relay O, having one coil o in series with the armature 1 and a second coil o<1> in shunt, is arranged to close the circuit of a controller-locking device K' on an overload. In starting, the switch L is turned so that the right-hand movable contacts engage the fixed contacts, and, upon rotation of the controller K to the first position, a circuit is completed from one terminal of the exciter a<2> through contacts 3, 4, 5, 6, train-wire 44, actuating-coil of the switch T, and ground to the opposite terminal of the exciter, closing the switch T. A branch circuit passes from the contact 6 through contacts l<1>, l<8>, l<2> to the train-wire 40, through the actuating-coils of the switches T', T<2>, U to ground, closing the switches and reversing the connexion of the coil o<1> of the relay O. Another circuit passes from the contact 7 through contacts 8, l<3>, l<9>, l<4>, train-wire 41, and the actuating-coil of the series switch S to ground, closing the switch. A motor circuit is then established from the upper terminal of the armature 1 through the relay coil o, switch T, resistances R<1>, R<2>, armature of the motor M<1>, switch T', field winding of the motor M<1>, switch S, resistances R<3>, R', armature of the motor M<2>, switch T<2>, and the field winding of the motor M<2> to ground, as shown in Fig. 2. In the second position, a circuit passes from contacts 9, 10 to the train-wire 39, through the actuating-coils of the switches R<a>, R<c> to ground, closing them and cutting out resistances R', R<3>, and in the third position resistances R<2>, R<4> are cut out. In the fourth to the eighth positions, resistances R<5> ... R<9> are cut out, increasing the field strength of the generator and the electromotive force at its terminals. In the ninth position of the master-controller, the segment 7 leaves the contact 8, opening the series switch S, and all the resistance-controlling segments leave their cooperating fixed contacts, re-inserting the resistances. The segment 15 engages the contact 16, and a current passes through the contacts l<5>, l<0>, l<6>, train-wire 42, and the actuating - coils of the switches P, P' to ground. The motors are then in parallel with their corresponding resistances. The excitation of the generator field is again at its lowest, and, on further rotation of the controller K, the resistances R<1> ... R<4> in the motor circuit and the resistances R<5> ... R<9> in the generator field circuit are successively cut out. When it is desired to brake, the switch L is moved so that the left-hand movable contacts engage the fixed contacts, and, on rotation of the controller K to the first position, a circuit passes through the contacts 3, 4, 5, 6 and the actuating-coil of the switch T to ground, and a branch circuit passes from the contact 6 through the contacts l<1>, l<11>, l<12>, l<7>, train-wire 43, and the actuating-coils of the switches B, B<1>, B<2>, B<3> to ground, the circuit also branching and passing through the actuating-coil of the switch P' to ground. The switches T, B<1>, B<2>, B<3>, P' are closed, and circuits are closed, one through the motor armatures and resistances R<1> ... R<4> connected in parallel to the armature a<1> and the other two circuits in parallel to the exciter a<2>, one through the field windings of the motors in series with resistances r<1>, r<2>, r<3>, and the other through the field winding of the generator in series with resistances k<5> ... R9, as shown in Fig. 3. The motors then operate as separately-excited generators supplying current to the generator a<1>, which acts as a motor and drives the motor a above synchronism so as to return energy to the line. The master-controller may then be operated so as to cut out the resistances R' ... R<4> and then to strengthen the generator field by cutting out resistances R<5> ... R<9>. The requisite braking steps can be obtained through the action of the controller K, and the master-switch H, adapted to cut out the resistances r<1>, r<2>, r<3> in the circuit of the motor fields, may be used to regulate the speed