Patent GB-190406041-A (GB)
Title: Improvements in Electric Arc Lamps
Inventor: LEVIS HOWARD COPPUCK
Filed: 1904-03-11
Granted: 1905-02-16
Abstract: 6041. Levis, H. C., [General Electric Co.]. March 11. Arc lamps.- The lower electrode is directly connected to the core of a shunt solenoid, which is cut out of circuit when current flows through the electrodes, so as to allow the lower electrode to fall. In order to limit the length of arc thus struck, the lower electrode is also connected by a lost-motion arrangement t o a clutch device, which it can only move upwards. The upper electrode 15 may be of copper or other good conductor, so as to be non-consuming, and is formed in one piece with, or secured to, a plate 13 of similar material. The plate 13 is attached by means of screws 14 with insulating-bushings to a plate 9 of the lamp-frame. The negative electrode 46, which may be formed of or contain materials such as oxide of iron or titanium carbide, giving a flaming arc, is placed in a holder 45. The holder 45 is connected by a cross-piece 44 and rods 43 to a bar 42, to which are attached the cores 23 of the solenoids 6, a bridge-piece 24 of magnetic material, and a rod 25. Fixed to the rod 25 is the piston 33 of a dash-pot, the shell 28 of which is pivoted to a screw 29. The downward motion of the piston 33 of the dash-pot is limited by a shoulder 32 on a piece 31, adjustably attached to the shell 28. A box-like frame 36 embraces bars 2 screwed into a plate 1 of the lamp-frame, and has pivoted to it levers 38. The levers 38 are bevelled at their outer ends to engage and grip the bars 2, and are formed at their inner ends with upper and lower knifeedges, adapted to be engaged by nuts 39, 40 on the screw 29. A spring 41 is compressed between the nut 39 and a bridge-piece 34 attached to the frame 36. A nut 35 is provided on the end of the screw 29. When the dash-pot shell 28 is moved upwards, the nut 40 lifts the inner ends of the levers 38, and disengages their outer ends from the bars 2, so that the frame 36 is free to rise. Attached to the plate 1 in front of the solenoids 6 is a U-shaped piece 47, represented in Fig. 3, of conducting-material such as copper. Below the upper leg of the piece 47 is secured an electromagnet, having a core 48, end-piece 49, yoke 50, and armature 51 pivoted to the yoke, all of magnetic conducting-material. The electromagnet, U-shaped piece 47, and plate 1 are insulated from one another. The winding 52 of the magnet is in series with the arc. When no current is flowing through the electrodes, the armature rests against a screw 53 in the piece 47, and closes a circuit from the lamp terminal 62 through the conductor 67, yoke 50, armature 51, piece 47, conductor 65 attached to a binding-screw 66 on the piece 47, the solenoids 6, and conductor 63 to the terminal 61. Upon the closing of the main circuit by the raising of the electrode 46, the magnet 48 raises its armature 51 and breaks the shunt circuit, allowing the electrode 46 to descend by a distance limited by the dash-pot. If it is desired that the lower electrode should be fed upwards without the arc being broken, means may be provided, such as a coil in shunt to the arc, which will close a temporary shunt about the windings of the electromagnet 48 or otherwise diminish the excitation of the magnet whenever the voltage of the arc rises too high, or in a constant-current system the current to the lamps may be interrupted at the supply station when the voltage of the circuit rises unduly. With electrodes of the character descibed, no feeding is required during the normal period of working of the lamp. The upper electrode 15 is surrounded by insulation 17 of mica or other material, and outside this by a porcelain or other tube 18. Attached to an annular disc 10 is a cylinder 19. The tube 18 and cylinder 19 are of nearly the same length as the electrode 15, but the insulation 17 is somewhat shorter. The disc 10 is secured by bolts to the plate 9, and between the two is a removable cylindrical piece 21, provided with perforations 22 for ventilation. The plate 9 is attached by posts to a plate 5, between which and the plate 1 the solenoids 6 are secured by means of bolts 7. The rods 2 carry at their upper ends a cross-piece and suitable means for suspending the lamp, and may be screwed into the upper end plates of the solenoids 6. A cylindrical casing (not shown) extends between the plates 1, 9. The globe is held by screws 59 passing through lugs 58 on the disc 10.