Patent GB-190512964-A (GB)
Title: Improvements in Electric Arc Lamps.
Filed: 1905-06-22
Granted: 1906-03-08
Abstract: 12,964. British Thomson-Houston Co., [General Electric Co.]. June 22. Arc lamps.-The upper electrode of a lamp o the kind described in Specification No. 7660, A.D. 1904, is held by a clutch from which it is only released when this is struck by the lower electrode. The lower electrode is carried by two rods, each engaged by a clutch, one for raising the electrode and the other for limiting its descent. The upper electrode 75, Fig. 1, is contained in a tube 67 within a chimney 1 forming the backbone of the lamp. A collar 68 on the tube 67 has curved arms 69 which are attached to the inside of a copper or like hood 64, secured to the end of the chimney 1. A sleeve 73, adapted to slide over the lower end of the tube 67, has pivoted to it pawls 72, which are connected by links 71 to the collar 68, and are normally pressed against the electrode 75 by the weight of the sleeve. A tapered sheath of copper or the like is attached to the sleeve, and is protected by a shield 77 of refractory insulating-material, such as fire-clay ; these parts are preferably arranged so as to be replaceable. The electrode 75 burns down, in use, within the sheath, so that when released it strikes the lower electrode with some force, which may be augmented by a follower-block placed in the tube 67. On the descent of the electrode 29 to strike the arc, the electrode 75 slips a little way through the clutch before it is gripped by the latter. A solenoid, supported by an arm 15 and a collar 14 on the tube 1, has a movable core 16 with a disk 17<1> attached thereto, both being slotted when alternating current is used. A groove in the disk and a rib 18 on the chimney 1 guide the core. Links 20 connect the disk to pawls 21, which are pivoted to a sleeve 22 and have jaws 25 adapted to engage one of the rods 23 supporting the electrode 29. The sleeve 22 normally rests on a guide-tube 24. The other rod 27 is engaged by a clutch (not shown) consisting of a sleeve and of a pawl, the outer end of which is attached to a long helical spring, tending to keep the inner end pressed against the rod. A narrow vertical plate, attached to the base-plate 12, has a number of holes in which can be inserted two pegs, serving respectively to limit the descent of the pawl and sleeve and to disengage the pawl from the rod. A collar loosely surrounding the rod and resting on the end of a guide-tube 28 is attached to a short vertical rod which passes through a guide in the base-plate 12 and has a button at its lower end. A shunt solenoid 45, Figs. 1 and 3, has a movable core consisting of a tube 50 and a disk 51. Supported by an insulating plug 55 in the upper end of the tube 50 is a rod 56, which passes through a second plug 57 in a fixed tube 54 of magnetic material, and carries a carbon contact-piece 58, preferably screwed on the rod so as to be adjustable in position. The core is partly supported by a spring 59', bearing against a pair of nuts 59 on the rod, and is connected to one member of a dash-pot 53. When raised, the contact 58 engages springs 62 carried by a plate 60, thereby closing a second shunt circuit through the other solenoid, and causing the lower electrode to be raised into engagement with the upper one. This solenoid is so arranged that, should the arc fail, it takes sufficient current to protect the solenoid 45 from injury. The lower electrode contains preferably 90 per cent of titanium carbide and 10 per cent of carbon, the upper one consisting of a shell of carbon with a filling principally of titanium carbide. The chimney 1 consists of two parts 2, 3, the former having ventilating-holes 9 protected by a hood 7, and is preferably of non-magnetic material.