Patent GB-190503573-A (GB)
Title: Improvements in Electrical Means for Starting Prime Movers for Electric Generators and Controlling the Current
Inventor: SCLATER ARTHUR WILLIAM
Filed: 1905-02-21
Granted: 1906-01-11
Abstract: 3573. Sclater, A. W. Feb. 21. Turning-gear.-Relates to means for starting prime-movers for driving shunt dynamos, and consists in running the dynamo as a motor until the prime-mover is running on its own fuel, a fieldmagnet series winding being connected in circuit while the dynamo is running as a motor so, as to energize the field-magnet in the same sense as the shunt winding, and afterwards being disconnected when the dynamo is acting as a generator. In starting the dynamo D, Fig. 1, as a motor, the arm 4 of the starting-switch SA is moved by means of the insulated handle 5 towards the arm 3. The field shunt circuit sc is thus completed through the winding of the armature rca of the reverse current switch RC, metal bar s<1>, brush 7, winding of an electromagnet 6, brush 8, metal bar s<2>, and a variable resistance vr to the pole b<1> of the battery B, B', the other pole b of the battery being connected to the other end of the shunt winding sc through the overload cut-out OL, change-over switch S, and field series winding dsw. When the arm 4 has been moved to its extreme left-hand position and has become locked to the arm 3 by a hook 9 carried by the armature of the electro-magnet 6 engaging with a pin o, it is moved back to its original position, the circuit through the armature da being thereby completed through the arm 3 and the resistance vr, which is gradually cut out. Should the current through the armature da rise above a predetermined value, the overload electromagnet OL short-circuits the winding of the electro-magnet 6 so that the hook 9 releases the pin o and allows the arm 3 to fly back under the influence of the spring 14. The overload cut-out OL may be placed in the conductor c instead of in the conductor h. The two locked arms 3, 4 are held in their extreme right-hand position by a hook 11 engaging with the arm 4, and, in order that the field shunt circuit sc may not be broken when the brush 8 leaves the contact-bar, the' arm 3 is provided with a brush 15, which engages with a bar S' and is connected to the brush 8 by a conductor 16. When the speed of the dynamo has attained such a value that the prime-mover S is running on its own fuel, the change-over switch S is moved from the contact m to the contact g, thereby cutting out of circuit the field series winding dsw and completing the armature circuit through the reverse-current cut-out switch RC. This switch acts when a current passes through it from the battery to the dynamo by repelling the armature rc and so shortcircuiting the electro-magnet 6. A permanent magnet may take the place of the armature rca. In place of the shunt dynamo D, it may be desirable to use a compound-wound dynamo, in which case the field series winding dsw is not cut out of circuit when the change-over switch S is operated, but the connexions are so altered as to reverse the direction of the current in the winding. The dynamo D may be used in combination with a booster H, Fig. 2, the two machines being mounted on a common shaft M. The shunt field windings are connected between the bus-bars OB', OB<2>, the booster shunt winding through a variable resistance hsr, and the dynamo shunt winding sc through a variable resistance dsr and the starting- switch SA. The series windings dsw, hsw are connected in series when the dynamo 1 is running as a motor and disconnected from the circuit when the change-over switch S is operated, the switch W being on the contact n. When it is required to run the dynamo D in parallel with the battery BB<1> the change-over switch S is left open and the switch W moved to the contact z. In Fig. 3, the change-over switch is shown combined with the starting-switch. The arm 3 carries a contact 17 which is adapted to bridge the contacts of the variable resistance vr and the metal bar 18. When the arm 3 is moved into the position in which the contact 17 bridges the bar 18 and the contact 19, the field series winding dsw is short-circuited, further movement of the arm 3 disconnecting the winding from the circuit. The apparatus described above may be used for electrically starting, controlling, and reversing engines for wheeled vehicles and ships.