US2130871A - High speed tripping system - Google Patents

Description

Sept. 20, 1938. E. w. BOEHNE HIGH SPEED TRIPPING SYSTEM Filed Aug. 4, 1956 2 Sheets-Sheet 1 Fig.4.

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CURRENT a REROENT FOUNDS PUL L E. W. BOEHNE HIGH SPEED DRIPPING SYSTEM 5A TURA T/ON CURVE TIME IN SECONDS TIME IN SECONDS 3 TURNS Es F wag-6 l i I I AREA //v SQUARE INCHES by gfis fitovnev Patente am. 193 2,l30,811

UNITED STATES PATENT oFFlcE' man eru s-mo.

Eug cncW.Boehne, Yeadom l'as asllgnortoGeneyrgkmctfl company,aorpor atl otl-lew Application August 4 1m, No. 94,220 11 Claim (oi; Ira-zen Myinvention relatestohighspeedreleasing desimilar to the conventional method or tripping vices, such as for example those applied to the the breaker, that is in response to a fault conditrippins mechanism an electric circuit breaker tion in the high tension power line 2, such as a !or initiating high speed opening oi the breaker. short circuit for example, the current transforma The control 0! many other high speed operations, er causes energization of the relay], which in 5 such a'sthe quick automatic application 0! break- 'turn energizes the tripping or releasing means 3 ers' to rotating equipment is also contemplated. I for opening the breaker I. p I In high tension power systems operating at The operation and arrangement of the relay commercial frequencies, the duty of quickly isosystem which comprises no part of the present l0 latinga fault, such as a short circuit for example, invention are specifically described and claimed lo falls upon the circuit breakers controlling the in my copending application for control devices aflected part of the system. It is, therefore, and systems, Serial No. 94,219, filed concurrently essential that the'circuit breaker completely clear herewith and assigned to the same assignee as the circuit within a few cycles at the most in the present invention.

5 order that the stabllityoi the system shall not i The relay 4 comprises a permanent magnet 6 ll be upset. The operation oi a high tension oil having soft iron pole pieces 1 and a coacting armcircuit b r for example to clear the circuit ature carried on a pivoted contact arm 9. The may be vided into several stages; namely, disoperation of the armature 8-controls the contacts engagement of the tripping or releasing mechoi the relay switch indicated at S. The, magr 1" aniam in response to aiault'condition, initiation netomotive force producedby the permanent of opening movement of the breaker contact magnet 5 normally maintains the armature 8 in structure in response to release thereof, and openthe closed magnetic circuit position shown against ing movement of the contacts coincident with the bias of spring iii. When this magnetomotive the arc-interrupting operation. The present 111- force is overcome by the spring Hi, the relay as vention is primarily concerned w the first switch Sisclosed. For the purpose of controlling stare overationithe last two stages relating release or the armature a, a solenoid or tripping ore sp c to the circuit breaker and its coil H is related to the magnetic circuit above p mechanism described so that energization of said coil from A Principal of my invention therefore is the direct current control source I2 causes release the an impmved ugh speed trippmg oi the armature 8 and closing of the relay switch device which is eflgctwe appreciably S. To this end the current transformer 5 causes g fggg t tripping time over that heretofore in response to predetermined current in the line 2 actuation of the solenoid i3 for closing the conm'mvenflon Wm be more forth m the trol circuit at It. The relay control circuit also following descnpum referring to the accompany includes a current limiting series resistance I5 35 drawings and the matures novelty which and a capacitance it connected across the coil Muted my invention Wm be pointed II when the contacts at it are closed. It will, with particularity m the clam annexed to therefore, be apparent from the above descripforming"? oath: siinecifloflglonll I ti n that predet rmined energlzatiorl of the cure t e a y rent transformer 5 is effective to cause actuation diagrammatic view oi a circuit breaker operating or the rem y and closing of the relay switch S. system embodying the present invention, Fig. 2 The i t t I pping or releasing device 3, which is isasimplii'ied circuit diagram of circuit constants t ed th I i 1 I 1 d involved in mg. 1; Fig. 3 is a view or the tripping a es a Perm" mmetlgenerflly shown mm;- 1; Fm 4158'; -nent magne so ron poe pieces l8 and i9 Wave flew mwmung the structure the and an armature 20 of similar material. The mm how by m 3, and F188 mc1us1ve armature 10 is earried at M by a latch member are relating to the tripping magnet and 22 pivoted at It and biased by a tension spring circuit design factors. The circuit breaker oper- 13 -W y from the -8 The latch 22 s Proso sting system illustrated by Fig-.1 comprises an Vlded its pp 8 9 With an abutment 24 electric circuit breaker generally indicated at i arranged t en e n h i 88 generally indi tor the high tension power circuit 2, the circuit cated, the operating rod i of he circuit breaker breaker being controlled by a tripping magneto, in the closed circuit position. Normally, the which is in turn controlled by a relay 4 and cutmagnetomotive force produced by, the permanent as rent transiormer l. The operation in general is magnet i1 is eiiective to hold the armature 20 position against that energizatlon 01' the trip coil force at the armature 22 in a counterclockwise direction, thereby releasing the breaker operating rod l and permitting opening of the breaker. This general type of tripping device commonly known as the fluxshifting type, is shown for example by Tritle Reissue Patent No. 15,441 01' August 29, 1922.

Energization of the trip coil T may be efiected when the breaker l is closed by closing the relay switch S. The control circuit soestablished includes the control source I2, relay switch 5, auxiliary switch 25, which is controlled by the breaker I and assumes similar circuit controlling positions thereto, magnet trip coil T, auxiliary switch 26 which is controlled by the latch 22 so that it is closed in the holding position of the latch and vice versa, and series resistance R which is chosen, in

the tripping circuit, is connected across the trip coil T when the relay switch S is closed, as diagrammatically illus trated by Fig. 2. I

Immediately upon release of the latch 22 in response to a tripping impulse, the latch controlled auxiliary switch 26 is opened, instantly deenergizing the trip coil T. Also, the circuit breaker in moving to open circuit position causes opening of the auxiliary switch 25, which is also in series with the relay switch 3. The latch controlled auxiliary switch 26 operates considerably fasterthan thebreaker controlled auxiliary switch 25, the latter serving more as a back-up switch for insuring that the circuit of the trip coil is open when the breaker is open.

The breaker also controls auxiliary switch contacts at 29 included in the control circuit of the resetting coil 30 of the relay 4. included in the circuit or the resetting coil 30 are closing of That is, position the breaker rod I causes momentary closing of the exciting coilclrcuit at 35 so that the permanent magnet is recharged, so to speak,

' to its original magnetomotive force.

The resetting of the latch 22 when the circuit breaker is to be reclosed can be accomplished in any suitable manner, such as by a mechanical connection (not shown) operatively interconnecting the breaker closing mechanism (also not shown) and the latch 22. immediately reset after the can also be manually tripped if desired.

Referring more particularly to the tripping device 3, the permanent magnet portion I1 is prefr erably composed a precipitation hardened product, basically an iron-nickel-alummum alloy, and specifically a character described and claimed in cuts 1,947,274 and 1,968,569. This magnetic alloy has certain highly desirable qualities for a permanent magnet material, such as for exally designated by the flux arrows H.

The trip coil T, which includes a soft iron laminated core 36 spaced by non-magnetic members 31 from the pole pieces l8 and I 9, is positioned in shunt with respect to the aforesaid magnetic circuit so that when the coil '1 is enerso that the spring 23 is effective to pull the armature away from the magnet.

In designing the magnetic path of the magnet including the armature Accordingly, in the holding position the magnet must exert a pull in excess of this, such as 500 pounds for example. Knowhowever, by design or the trip signed for approximately of turns fa predetermined amount and by in-' saturation curve for the annature metal. Knowing the most eiiicient saturation curve, the optimum area of the armature for maximum force may readily be computed. Fig. 6 illustrates the relationship between eflective armature pull and the area of the armature.

Heretoiore tripping magnets of the character in question utilized-an electromagnet energized from a direct current source rather than a permanent magnet, hence soft ironc'omprised the main, ii not the entire part, or the rnagneticcircult including the armature. In accordance with the present invention, part of the magnetic circuit. including the ineilective path or the trip coil flux has comparativel high reluctance so that the trippingflux is concentrated at the armature where it is most eiiective.-' Since the division of tripping flux between its two paths .3. and 39 (Fig. 3) depends on the reluctance of these paths, it will be seen that a high reluctance path through the permanent magnet and a comparatively low reluctance path through the armature 20 are desirable. This is accomplished by using the precipitation hardened magnetic alloy of the character above described for the permanent magnet since this alloy has a permeance of 2 as compared with l for air and 1000 to 2000 (or iron. This practically amounts to an open circuit for that part of the trip coil flux 30.

Referring again to Fig. apparent that the flux indicated at I! would be weak as compared with the magnet flux at 38. This insures taster building up or the bucking flux in the armature to a tripping value. Also the soft iron laminated pole pieces I! and is, which are particularly designed for low losses form for the trip coil flux 38 a path permitting a high rate or flux build-up.

The most marked increase in tripping speed over prior devices oi this character is obtained,

coll T. Heretoi'ore -a comparatively large number or ampere turns of the trip coil were considered not only desirable but essential for effective tripping on the assumption that a most eflective. For example, in a commercial form of tripping device using adirect current electromagnet having torce'ot the degree in question, the trip coil is deiound that by appreciably reducing the number sorting in the trip coil circuit externally of the trip coil a compensating non-inductive resistance,

, the iiux required for tripping builds up in the armature at a much higher rate.

In other words,

the armature the spring 23 in 20 is released by much shorter time when the trip' coil is designed in accordance with my invention since the bucking ilux at 38 more quickly eaches a value counf teracting the main magnet cordance Figs. '1 and 8 illustrate graphically the improved operation when the trip coil is designed in acwith my invention. The value H, or number of ampere turns in terms of force required to trip the armature isreadily known 1. e. the diilerence between the magnet pull and the spring pull or approximately 200 pounds. With a given source of direct current voltage and a fixed magnitude of ultimate trip coil current, I have found that by properly relating noninductive ex-. ternal resistance to a reduced number of turns there results not only a new value of ultimate current for tripping but also a great decrease in point for operation on the a magneto-motive- 500 turns. I have from 400 to 500 for example, the tripping cur- 1 rent, although being a. small part or the ultimatetrip coil current, nevertheless requires approximately .003 second in order to bring the tripping flui': up to its 'eflfectiv The coil having' eighty turns, however, higher percentage or the ultimate trip coil current to produce tripping, is eflective to cause tripping oi the armature in less than .001 second. It will, therefore, be apparent that tripping speed may be appreciably increased by properly relating the factors above referred to.

The relationship between the tripping time and the number of turns of the trip coil T is graphically illustrated by Fig. 8 which clearly shows that the tripping time for a given ultimate maximum current increased if the number of turns of the trip coil is decreased or increased with this value being the present inthe trip coil itself. the electrical conditions involved in this high speed tripping is believed to be unnecessary for a complete understanding of the present invention, other than to pointout that the inductance of the trip coil is reduced by the reduction in the number of coils, and this decreased inductance is connected in series with an external non-inductive resistance for fixing the ultimate trip coil current.

It may be noted at this point that the latch controlled auxiliary switch 26, which operates practically instantly on tripping, limits the trip coil current to approximately its tripping value, that is about '70 per cent of the ultimate value as indicated by Fig. 'l.

Although the above described tripping device is several times faster than any other releasing" or tripping device known to me, the tripping operation may be even further speeded up by connecting'a capacitance C across the trip coil as diagrammatically illustrated by Fig. 2. The capacitance C is connected on the coil side of the auxiliary switch 26 and on the'supply side of the relay switch 8. Accordingly, when the auxiliary switch 26 is opened in accordance with a tripping operation to interrupt the trip coll current, the capacitance prevents a high inductive surge by acting as a reservoir for the stored energy in the coil T.

When the breaker is .closed, the auxiliary switch 26 is closed and the relay switch open so that closing or the switch S not only completes the trip coil and battery circuit but also completes a shunt circuit including the capacitance C and the trip coil. Since the capacitance remains charged at the voltage of the source or battery I! when the switch S is open, closing oi this switch causes a rapid discharge through the trip coil, thereby increasing the rate of building up of the tripping current. That is, the capacitance in shunt with the direct current source acts as a transient booster in speeding up energization of the trip coil.

The improved operation due to the capacitance C can be understood irornthe following analysis.

to include practically all of the s fidt Eto should be comparatively large.

The eilect of the capacitance C in the present instance is graphically illustrated by Fig. 9 wherein curve a. represents the circuit of Fig. 2 without capacitance and curve b represents the circuit as shown. It will be noted that the current reaches the tripping value on curve b in time than in the case of curve a. be noted that the optimum numthe tripping coil is still further It should also ber of turns of out the capacitance.

It shall be understood, of course, that the above described improvements in the trip coil circuit can be applied generally to a tripping magnet, regardless of whether the magnetomotive force is by an electromagnetor permanent mag the relay 4 is preferably similarly designed so that closing of the relay switch S takes place practically instantly in response to a fault condition.

It should be understood that my invention is not limited to specific details of construction and arrangement thereof herein illustrated, and that What I claim as new and desire to secure by Letters Patent in the United States is:

1. A high means. for controlling energization ping coil. I

gizing said tripping coil, the number of turns of said tripping coil being related to the c0nstants of the circuit of the tripping coil to eifect an optimum with respect to the rate of building up of said tripping flux to the tripping value.

pacitance by reason of said shunt relationship also serving to absorb the stored energy 01' said coil when said shunt circuit is disconnected from said source.

trolled by said tripping armature movable between two positions, an armature releasing coil having a magnetic path related to the magnetic circuit including said armature, a charging coil for said permanent magnet portion, and a switch controlling the circuit of said charging coil arranged to be momentarily closed in accordance with the tripping operation of said armature.

'7. A high speed tripping magnet having a magnetic circuit including a relatively movable armature normally held in closed magnetic circuit position by magnet, means biasing said armature towards open magnetic circuit position, an armature releasing coil having a magnetic path related to the magnetic circuit of said magnet, and an auxiliary switch controlled by said armature Ior instantly deenergizing said releasing coil in accordance with the release of said armature.

8. A high speed magnet having a magnetic circuit including a relatively movable armature normally held in closed magnetic circuit position by the magnetomotive force of said magnet, means biasing said armature towards open magnetic circuit position, an armature releasing coil having a magnetic path related to the magnetic circuit of said magnet, and a control circuit for said coil including a source oi. direct current, a non-inductive resistance, a normally open control switch, and a capacitance connected in shunt with said source oi direct current and noninductive resistance, said capacitance being so related to the ohmic resistance oi said tripping coil and said non-inductive resistance that closing of said control switch causes an initial discharge from said condenser to said trip coil so as to increase the rate of build-up of the tripping flux of said coil to the tripping value.

9. A high speed releasing magnet of the fluxshifting type comprising a source of magnetomotive force for establishing a holding flux, a tripping coil for establishing a releasing flux, a source of electromotive force for energizing said tripping coll, a capacitance arranged to be connected in shunt with both said source of electromotive torce and tripping coil, a non-inductive the magnetomotive force of said resistance of appreciable value in the connection between said source of electromotive force and said capacitance, and a control switch adapted to connect said capacitance in shunt with said trip coil for discharging said capacitance through said coil substantially coincident with energization of said coil by said electromotive force, said switch also establishing a circuit whereby said capacitance subsequently absorbs the inductive energy of said coil.

1 10. A high speed releasing magnet oi the fluxshiiting type comprising a source of magnetomotive force for establishing a holding flux, a tripping coil for establishing a releasing flux, a source of electromotive force for energizing said tripping coil, a capacitance normally connected in shunt with said source of electromotive force, a normally closed control switch and a noninductive resistance of appreciable value being included in said shunt connection, and a second normally open control switch for connecting said source ofeiectromotive force in series with said tripping coil and also said capacitance in shunt therewith for causing discharge of said capacitance through said tripping coil substantially coincident with energization of said coil by said source of electromotive force.

11. A high speed releasing magnet of the fluxshiiting type comprising a source of magnetomotive force for establishing a holding flux, a tripping coil for establishing a releasing flux. a source of electromotive force for energizing said tripping coil, and a capacitance arranged to be connected in the tripping coil circuit in shunt with both said source of electromotive force and tripping coil, the circuit constant ratio being comparatively large where R is the noninductance resistance oi that part of the circuit including the capacitance and source of electromotive iorce, and r is the non-inductive resistance of the tripping coil.

EUGENE W. BOEHNE.

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