US1225587A - Protecting means for transmission systems. - Google Patents

Description

E. E. F. CRElGiTG-l. PROTECHNG MEANS For@ mmsmssmw SYSTEMS. APPLICATION FILED MAY 14, 1913.

Wi Uw onerose,

ELMER E. F. GltEGl-ETON, 0F SCHENECT.F`DY, NEV YORK, ASSGNOR TO GENERAL ELECTREG CQMPANY, A CORPRAEEN Gli NEW YURK.

'LU EETECTING MEANS FSR TRNSMISSIQN SYSTEMS.

incassa l eppueaoen sied nay 14, i913.

To o whom it may concern:

Be it known thatl", Emmi; E. l?. Cnniorn 'r-oN, a citizen of the United States, residing at Schenectadyin the county of Schenectady, State of Neu7 York, have invented certain new and 'useful improvements in Protecting Means for Transmission Systems, of which the following is a speciiication.

ly invention relates to transmission systems and the object of my invention is to provide for the protection of transmission systems against the production and continnance thereon of certain unduly high voltages and the prevention of oscillations of the energy thereon, Jproduced by the discharge of energy from or to one or more of 'the conductors ott the transmission system.

Various causes produce discharges of energy' between conductors of a transmission system, and between a conductor of a' tem and ground. Such discharges often take place through the air ,between a. grounded metallic body and a conductor, or between conductors. Such an arc is oscillatory in character unless special provisions are made and as a result gives rise 'to oscilla tions of energy on the system which are likely to produce disastrous results to the attached apparatusA` as by the building up of potential in a. manner Well understood. l accomplish the object oi? my invention, as set forth above, by requiring that a necessary exchange of energy between conductors of a, system or 1oetween a conductor and ground take place at a certain point by reducing the insulation value at this point or otherwise localizing the difflarge, and requiring that the disch-arg energy pass through a resistance of approximately the critical value. ln one aspect of my invention, it is immaterial whether the discharge takes place from one conductor of current to another conductor of current, completing a icircuit through the arc, or Whether the discharge takes place between a conductor ot a system of distribution, as one plate of a condenser, and another conducting body, as the earth, as another plate of a condenser. ln either case the discharge may be said to take place between two conductors. As is well known, a discharge of electrical energy through a resistance of, or greater than, the critical value is aporiodic, hence such a discharge cannot produce oscillations ciI the Specification of Letters Patent.

Patented May 8, 1913?, serial no. 767,543.

energy on the system. The critical value of the resistance, as is 'Well understood, depends upon the inductance and capacity of the system as a whole, or the part of the system immediately related to the discharge point.

it is not necessary that the resistance be of exactly the critical value. lf itis greater than the critical value, the only e'ect is, tiat the discharge energy over it taires an unnecessarily long time, and even though theresistanceis ci" very much less than the critical value, the advantages of my invention are obtained. For example, though the resistance used is cfa value of but one-tenth the critical falue, the oscillatory character is very materially changed for discharge is still oscillatory the number of oscillations is strictly limited. Therefore, if the particular system to which my invention may be applied is capable or' standing the occurrence of a number of oscillations without the development of a. fault, .it is quite possible to use a. resistance having a 'alue .'ery considerably less than the critical value, eren than one-tenth of the critical value. For this reason the word approximately hereinafter used in the specification aud'claims must he given a very. broad interpretation for I intend Ithe errpression approximately equaltol` thc critical value, and similar expressions, to include resistances oi" the critical value, resistances between the critical value and even less than one-tenth of the critical value, and resistances oi a somewhat greater value than the critical value.

ln carrying out my invention with overhead transmission lines employing metal towers or masts it is convenient to mount an airing' ring ou the insulator carrying the conductor and connect this ring to the mast or tower through a resistance member so that 'the total resistance offered to a discharge from or to that conductor is of approximately the critical value. It is only necessary as will be understood, to connect the resistance to whatever metallic body is most likely to receive the discharge and insulate the metallic body except tor this connection. ln systems using an overhead ground wire, a path or" approximately critical resistance would be maintained between sanctions ol. the groumlfwiro amlprouml in the although the connue-tors are generally carried onnecir-d to thc sheath ol' i manner illustrated, in principle, in gui-e i case olfunderground systems the i through eahles 'having nicizillic slieaths. ny discharge conductor "to ground,'thereiorej t lies place through the niet-allie sheath.

'Prfer with such eins, therefore, to carry ut iny invention o; keeping the sheath out oi general connectiiu ufith the earth lijf inng it in any manner und connecting t -e sheath to th earth at one. or more points through e, rosier ree er of approximately the enti, value. A discharge @round i i re, taires nlece to the sheath and through f c nnection to ground.

novel features oi' my invention may embodied a ninnher of dil'erent conu clons. l'n the accompanying drawings he i' s i. 'WL ch forni a part oi this speciiication, fi. have illustrated diagrammatically two possible constructions embodying the novel fea.- tures of my invention in which: Fig. l illustrates one Way of applying my invention. to an overhead transmission line, and Fig. 2 illustrates the principle of my invention as applied to o. cable. p

In Fig. l the mast l. carries suitable arms @fior supporting the insulators carrying the endnctors. T insulator 3 is carrie-d on a n attached to one of the arms or' the est.V On this insulator is carried the conductor-5. In carrying out 'my invention 'with such. overheadtransmission line it is sa lsactory to attach the resistance inem-- her tothe inast at one end and the other end. to any metallic hotly which is so loca 'ed as to mest likely receive the are from the adiacent conducton this .metallic body being insulated other than through the resistance. lin this particular cas; l have illustrated an arcing ring' 6 of common construction, carl Electricallf,7 con the. cond uetor 5 o at .least for any discharge which nia y tal-re place i'roni a given part o'F the Conductor 5, the system as a whole being thus protected against discharges where their occurrence would he especially langen ous or .uulesirahle.

ln Fig. i) is shown a cahle 'l0 haring the customary memllicuhratln usually ci' lead. rThis cable .is showin.nim-ely tor purposes oi illustration7 as '.arryiug three conductors.

hr cable if; :L Cou- Leones.

Erein, one or he coiuhictors7 therelated fron: the ground other than through the connectors. Now it is possible to attach a number of the grounding connections to :i cable, preferably spacing 'them approximately equal distances apart, the sheath of' the cable being continuous electrically. It may also he desirable ut times to break the sheath into sections insulated from each otl'icr, as shown at In this case each section should have one or more grounded connections.

By this construction surges or oscillatory .discharges occurring on any conductor of the cable are removed from the conductor and prevented from building up voltage peaks, due to the :tact that the cable sheath forms with its path to ground an inductively related circuit of approximately critical resistance, whereby upon the occurrence of an oscillatory surge, energy is induced from the conductor to the inductively related circuit and such energy removed from the conductor to ground as on aperiodic discharve. Applying these principles of protection to cn overhead ground Wire systeni, the ground wire would be connected to earth in sections, through resistance aths of approximately critical velue and therefore in like manner 'would remove from the conductor any oscillatory disturhancerJ ucnperodic discharges.

llf'hct l. claim asx nv and desire to secure by Letters Pute.- vr e UnitedStates, isz-- l. The ecinlnnnticn with an electrical conductor, oi menons.; said conductor for loculi-zing discharges from said conductor, supports'ior said ineens providing pathsto vground from said means, and means conneetmgsmd'supports and said first mentioned means `coperatng with said supports to provideypaths having i a. resistance eueient to render".dischargesl suiiicicnt to render all discharges over the 1.20

.saine non-os lhr'rory.`

3. The combination with an electrical cmnluctor7 of an insulated metallic member positioned relative to said conductor toreduc'e the insulation value of said conductor at that point, a support for said member,

and a resistance between said inemher and sind support which combined with the resistance or said support provides path hav ing a total resistance to conduct all dis- 130 located in proximity to f ehrges to ground and render them nonn Witness whereof, have hereunto set eeciilatery. my hand this 12th day of May 191.3.

The combination With en electrical con- T dilater, an insulating support therefor, an ELMER E' F' CREGHT" iiicin'giring carried by Said support, and a Witnesses: connection to ground from said ring having HELEN ORFORD,

a resistance of applzoximately critical value. BENJAMIN B. HULL.

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