US1788437A - Lightning arrester and method of making the same - Google Patents

Description

Jan. 13, 1931. J. R. M FARLIN 1,733,437

LIGHTNING ARRESTER AND METHOD OF MAKING THE SAME Filed Feb. 11, 1924 Patented Jan. 13, 1931 UNITED STATES PATENT OFFICE JOHN ROBERT MOFARLIN, 0F PHILADELPHIA, PENNSYLVANIA, ASSIGNOR TO ELECTRIC SERVICE" SUPPLIES COMPANY, OF PHILADELPHIA, PENNSYLVANIA, A CORPORA- TION OF PENNSYLVANIA LIGHTNING ARRESTEB AND METHOD OF MAKING THE SAME Application filed February 11, 1924. Serial No. 692,144.

My invention is designed to provide an improved device for eifecting the ready discharge to ground from a protected line or instrument of currents, or other electrical manifestations of abnormal potential, such as lightning, while preventing leakage of normal current to ground. My improved arrester is particularly adapted for the protection of apparatus such as is connected with razlio antennae, but is also suitable for the protection of low voltage direct and alternating current circuits for operating signals, alarms and the like, for the protection of apparatus connected to alternating current circuits of 115, 230 volts or higher, or for general use.

Leading objects of my invention are to provide, in a simply constructed and inexpensive device, means for effecting and maintaining accurate positioning of gap electrodes and nice adjustment of the air gap between them, and to provide for the gap electrodes a secure- 1 I sealed non-conducting shell excluding tiierefrom dust, moisture or corroding gases, with avoidance of the corrosion of the elec trodes and closure of the air gap commonly material, as bakelite, about the knurled or.

corrugated bodies of binding posts to form complementary shell sections having air tight joints with the binding posts embedded therein, the shell sections being adapted for connection with one another to provide an electrode housing containing an expansion chamber having a sealed peripheral joint. The binding post body and the gap electrode of each shell section are connected together in telescoped relation and the gap face of the electrode positioned in predetermined relation to a fixed point of the shell section, and preferably with relation to the bearing surfaces of shell lugs adapted to abut against bearing surfaces of similar lugs of a complementary shell section to space the gap electrodes and limit the pressure on the packing in the peripheral joint formed by the connec-; tion of two shell sections.

The characteristic features and advantages of my improvements will more fully a pear from the following description of a pre erred embodiment of my invention and the accompanying drawings in illustration thereof.

In the drawings, Fig. 1 is a vertical sectional view of an arrester embodying my improvements, the section upon which the view is taken being indicated by the lines 11 of Fig. 2; Fig. 2 is a bottom plan view, upon a reduced scale, of the upper casing section or cap; and Fig. 3 is a transverse sectional view taken on the line 3-3 of Fig. 1.

As illustrated in the drawings, my invention is embodied in a lightning arrester comprising a pair of easing sections or caps 1, 1' moulded from plastic insulating composition, such as bakelite, and hardened. Each shell section or cap has embedded therein while plastic the knurled orcurrugated body 2, 2 of a binding post 3, 3. The plastic composition is expanded axially along the binding posts to form extended bearings or hubs 4, 4 closely interlocked with the binding posts and providing moisture and air proof seals and rigid supports.

The shell section 1 contains a channel 5 adjacent to the periphery thereof and forming a seat for a packing ring 6. The shell section 1 is provided with a peripheral wall or flange 7 having a lip 7 registering with and adapted to be engaged in the channel 5 against the packing 6. The shell section 1 has moulded integrally therewith the lugs 8, connected with the hub 4 by the radial reenforcing ribs 9, the lugs having embedded therein the headed ends of bolts or rivets 10. The lugs 8 are adapted to pass within the peripheral wall 7 into abutting relation with similar lugs 8 integrally formed with the shell section 1 and connected with the lug 4: by radial reenforcing ribs 9. The lugs 8 contain rivet holes 11, terminating exteriorly in counterbored sockets 11' which provide seats for the fibre washers 12 over which the heads 10' of the rivets 10 are spun. If desired, the sockets may be filled with a suitable sealing compound, as wax.

The binding post bodies 2, 2' have axial sockets 13, 13' drilled therein to provide seats for the knurled gap electrodes 14, 14' having fins or serrations 15, 15' of slightly larger external diameter than the internal diameter of the sockets 13, 13; so that when the electrodes are pressed into the binding post socks they cut their way into the binding post stock and make a tight force fit therewith.

The external ends of the binding posts are milled to provide seats 16, 16 and drilled and tapped to accommodate screws 17, 17, whereby line and ground wires 18, 18 are secured to the binding posts. The arrester may be conveniently fastened to a support by means of the strap or band 19 engaged between the beads 20, 20.

In assemblin my improved arrester, after the moulded s ell sections have hardened with the binding post bodies and rivet heads embedded therein, the gap electrodes 14, 14' are first forced into the sockets 13, 13 and their gap faces positioned in predetermined relation to the bearing surfaces of the respective lugs 8, 8', or other casing surfaces determining axial positions of the casing sections relatively to one another. Such positioning of the electrodes may be suitably effected by an indexing guide on the forcing press.

The air gap distance between the gap faces of the electrodes when the arrester is assembled is a function of the relationship betweensuch gap faces and the indexing surfaces of the respective casing sections. For example,

when the respective gap faces are retracted relatively to the planes of the respective lugs 8, 8, the air gap between the electrodes in the assembled arrester will be the sum of the distances which the electrode faces are retracted.

When the electrodes are properly set, the casing sections are telescoped together with the lugs 8, 8 in abutting alignment and the lip 7 engaging the packing 6 in the channel 5. By upsetting the heads 10 of the rivets against the washers 12, the casing sections are securely fixed together and form a moisture and gas tight chamber containing electrodes accurately spaced in a very simple and economical manner.

Having described my invention, I claim: 1. A lightning arrester comprising a tight shell containing a peripheral groove, a strap engaged in said groove, a plurality of binding posts containing aligned sockets having closed outer ends and gap electrodes seated in the respective sockets and permanently fixed relative thereto.

. 2. A lightning arrester comprising a housing, a binding post and a gap electrode, said post and electrode being fixed together in telescoped relation and oneof said members having a serrated surface engaging the other member in fixed relation thereto and said post having serrations engaging said housing and extending transverselyto the serrations first named.

sections having radial reenforcm ri s and abutting bearings, said sections a so having hubs forming seats for aligned gap elec-. trodespermanently fixed relative to the re-v spective sections and spaced by the engagement of said bearings.

4. A lightning arrester comprising shell sections having members forming a joint between them' and an elastic gasket sealing said joint, said shell sections aving abutting bearings limiting the pressure on said gasket.

5. A li htning arrester comprising shell sections 0 hardened plastic material moulded around aligned binding posts, and gap electrodes telescopically connected with said binding posts, one of said members last named having fins embedded in the material of the other, and said electrodes being spaced by the engagement of abutting bearings of said shell sections.

6. A lightning arrester comprising conoidal shell sections of hardened plastic material moulded around binding posts at the.

apexes thereof and having gap electrodes seated therein, said shell sections having abutting bearings adjacent their Eeripheries of and forming a tight joint therewith, said shell section having a peripheral flange and spaced lugs, a second moulded conoidal shell section having a binding post set therein at the apex thereof in alignment with said binding post first named, said-second shell sec tion having members coacting with said flange and spaced lugs abutting against said lugs first named, and aligned electrodes connected with the respective binding posts and spaced to form an air gap by the alignment of the lugs of the respective shell sections.

8. In a method of forming lightning arresters the step which consists in moulding a plastic substance around a terminal to form a shell section, hardening the shell section, and pressing an electrode into telescopic relation to said terminal until its gap face is in indexed relation to a fixed part of said shell section.

9. The method of forming lightning arresters which comprises moulding'a plastic substance around a terminal to form a h0l-.

Images