GB190521931A - Improvements in Electric Arc Lamps. - Google Patents

Abstract

21,931. British Thomson-Houston Co., [General Electric Co.]. Oct. 27. Arc lamps. -The positive electrode consists partly of conductive material and partly of magnesia, a rare earth such as thoria, or other material conductive only at high temperatures. The arc is struck from the conductive part, and is transferred to the refractory part by movement of the electrode when the refractory part has become heated by conduction. In the form shown in Fig. 3, the refractory part is a block 8, held by screws in a dovetailed recess in a curved rocking- bar 5, of copper or other material, to form the upper electrode in the type of lamp described in Specification No. 6040, A.D. 1904. The lower electrode 10 is of titanium carbide, magnetite, or other material. The base-plate 1, Fig. 1, of the lamp carries a tube 2, which may form part of a central chimney. The electrode 5 passes through slots in the tube 1 and is attached at its ends to yokes 6, which are pivoted to the tube 2 and connected by links 27, 26 to the core 23 of solenoids 24. A tube 12 carrying the holder of the electrode 10 is guided by a rod 13 and engaged by two clutches 19, 21. An arm 16 on a rod 15 serves as an upper and lower stop for the two clutches respectively ; the clutch 19, the pawl of which is drawn upwards by a spring 20, is also provided with a lower stop 17, to limit the length of the arc struck. The pawl 22 of the clutch 21 engages the top of a dash-pot 25, which is attached to the core 23. The links 26, 27 are connected by a pin-and-slot device, and the clutch 21 is arranged so that, when the core 23 begins to ascend, it is allowed to acquire some momentum before it moves the electrodes. The solenoids 24 are in shunt to the arc, so as to bring the electrodes together when the current is switched on, and are then cut out of circuit by means of a series coil 35. If the voltage rises unduly, a high-voltage coil 39 closes a shunt circuit about the coil 35, causing current to flow again through the solenoids 24.