US3906413A

US3906413A - Current-limiting device for low-voltage electrical power systems

Info

Publication number: US3906413A
Application number: US505792A
Authority: US
Inventors: Challis I Clausing
Original assignee: ITE Imperial Corp
Current assignee: ABB Inc USA
Priority date: 1973-08-20
Filing date: 1974-09-13
Publication date: 1975-09-16
Anticipated expiration: 1992-09-16

Abstract

A current-limiting device is formed as a self-contained electrical component having terminals which may be identical to fuse terminals to allow the interchangeable connection of the device in a low-voltage circuit with a current-limiting or conventional fuse. The device is formed of a plurality of contacts which engage the opposite edges of a spirally wound coil, with the contacts sequentially opening to gradually insert the turns of the spirally wound winding in series with the circuit in which the device is connected. A magnetic core surrounds the windings in order to increase the inductance of the coil.

Description

United States Patent 1 Clausing CURRENT-LIMITING DEVICE FOR LOW-VOLTAGE ELECTRICAL POWER SYSTEMS [75] Inventor:

[73] Assignee: l-T-E Imperial Corporation, Spring House, Pa.

[22] Filed: Sept. 13, 1974 [2|] Appl. No: 505,792

Related U.S. Application Data [63] Continuation-impart of Scr. No. 39() 064 Aug. 20,

I973, Pat. No. 1836319.

Challis l. Clausing, Marlton, NJ.

[52] U.S. Cl 335/41; 317/11 C; 335/14;

335/[6 [5| lnt. CL- HOlH 77/06 [58] Field of Search 335/41, ll, l6, l4;

[56] References Cited UNITED STATES PATENTS Hayncs 335/41 1 Sept. 16, 1975 3.8363) 9/1974 Clausing 317/11 C Primary Examiner-Harold Broome Attorney Agent, or FirmOstr0lenk Faber Gerh & Soffcn [57] ABSTRACT A currentJimiting device is formed as a self-contained electrical component having terminals which may be identical to fuse terminals to allow the interchangeable connection of the device in a low-voltage circuit with a current-limiting or conventional fusew The dcvice is formed of a plurality of contacts which engage the opposite edges of a spirally wound coil with the contacts sequentially opening to gradually insert the turns of the spirally wound winding in series with the circuit in which the device is connected. A magnetic core surrounds the windings in order to increase the inductance of the coil.

25 Claims, 14 Drawing Figures PATENTEU SEP 1 8 975 SHEET 1 BF 9 a q W W W W W W W W W W m r w 4 .n I w W -wwWm/W F.\\\\\\\\\\\\\\\\ PATENTED SEP I 6 I975 SHEET 3 OF 9 W MI HN WHEN [H] SEP I 6 9. 5..

SHEET 5 OF 9 \Nm MNN ww PMEN'IEU 1 61975 sum 6 BF 9 t I g NNN I I L PATENIED I 6 5 SHEET 7 OF 9 NN E MWN CURRENT-LIMITING DEVICE FOR LOVV-VOLTAGE ELECTRICAL POWER SYSTEMS RELATED APPLICATIONS This application is a continuation-in part application of my copending application Ser. No. 390,064, filed Aug. 20, I973, now US. Pat. No. 3,836,819 entitled Current Limiting Circuit Interrupter Device and assigned to the assignee of the present invention now US. Pat. No. 3,836,819.

BACKGROUND OF THE INVENTION This invention relates to current-limiting devices, and more specifically relates to a novel current-limiting circuit component which is interchangeable with a fuse device and which may contain inductance increasing core means to increase the inductance of the winding which is inserted into a circuit in order to limit the fault current in the circuit.

Currentlimiting devices are well known to those skilled in the art and frequently take the form of current-limiting fuses or the like which tend to substantially increase circuit impedance over the range of their operation. Such current-limiting fuses are frequently used in combination with circuit breakers so that the fuse will tend to substantially limit the magnitude of fault current if the short circuit would exceed breaker rating. The circuit breaker interrupts relatively low currents up to its rating and the fuse clears fault currents which could have been supplied from the circuit being protected above the breaker rating. Other arrangements are well known for limiting the fault current in a circuit in which impedance. and particularly resistance. is sequentially introduced into the circuit as a circuit interrupter is operated.

My above-noted copending application discloses a particular current-limiting device which consists of an electrical winding having a plurality of turns. The winding is connected in series with a circuit to be protected. The individual turns of the winding are normally shortcircuited by individual contact elements bearing on opposite sides of the individual turns or groups of turns of the winding. These individual contacts are then springbiased into engagement with their respective turn. and are arranged to blow-of due to the magnetic field of a fault current which may be produced in this circuit. When these contacts blow off. the individual turn which they cooperate with is inserted into the power circuit. thereby to insert an inductive impedance in the circuit.

The various contacts may be further arranged so that they are sequentially forced out of engagement with their respective coils. so that the full impedance of the entire winding is relatively gradually inserted into the circuit.

The current through the circuit may then be limited either until it returns to some normal value. or the limited current can be interrupted by a conventional interrupter in series with the circuit. As pointed out previously. the current will be limited to a value within the rating of this main interrupter device. Once the current has returned to its normal value or has been interrupted by the main interrupter device. the individual contacts bearing on the turns off the helical coil can be reclosed by releasing latches which latch the contacts open when they reach an opened position.

BRIEF DESCRIPTION OF THE PRESENT INVENTION In accordance with the present invention, a particular configuration is provided for the coil in which a spirally wound winding is supported within an insulation support and wherein the contacts are supported on opposite sides of the winding by flanges extending from input terminals. The input terminals then have end regions which can permit the connection of the self contained device in a location which can also receive a conventional fuse. Thus, the entire self-contained current-limiting device of the invention becomes interchangeable with fuses which can be connected in preexisting equipment or any equipment which is to be manufactured in the future, with the ability to be used with either fuses or with the device of the invention.

The present invention further provides a novel con figuration for the operating contacts which gradually insert portions of the winding into the circuit being protected, and is further provided with a magnetic core for the winding in order to increase the winding inductance.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. I schematically illustrates the present invention where the current-limiting impedance is a helical windmg.

FIG. 2 is a side view. partially in cross-section. of a circuit breaker equipped with the novel currentlimiting device of the invention. wherein the impedance takes the form of a helical winding.

FIG. 3 is a cross-sectional view of FIG. 2 taken across the section line 3-3 in FIG. 2.

FIG. 4 is a plan view of the top of the circuit breaker of FIG. 2.

FIG. 5 shows a modified arrangement for the mounting of a contact finger.

FIG. 6 is a side view of a further embodiment of the invention wherein the coil is spirally wound as contrasted to the helically wound coil of FIGS. 2. 3 and 4.

FIG. 7 is an end view of the coil of FIG. 6.

FIG. 8 is a cross-sectional view through section line 8-8 of FIG. 7 which illustrates the inter-connection be tween the contact elements of the spiral coil.

FIG. 9 is a perspective diagram of the spirally wound coil used in the current limiter of the present invention. and schematically illustrates the placement of the contacts and of a magnetic core which is used to increase the inductance of the windings.

FIG. I0 is a front plan view of a completely selfcontained device which uses the concepts schematically illustrated in FIG. 9.

FIG. II is a top view of FIG. I0.

FIG. I2 is a front view of FIG. II.

FIG. 13 is an enlarged view of the small section 13-13 in FIG. 12.

FIG. I4 is a cross-sectional view of FIG. 12 taken across the section line 14-14 in FIG. I2.

DETAILED DESCRIPTION OF THE DRAWINGS FIG. I schematically illustrates the circuit of the present invention. and shows one phase of a power circuit having input and output terminals I0 and II, respectively. wherein a circuit breaker 12, which may be of any conventional type, is connected in series with terminals and 11 and is provided with a conventional operating mechanism.

The current-limiting device of the invention is shown as device 14 and consists of a multi-turn winding 15 connected in series with the main power circuit. The input side of the circuit has a conductive support I6 which supports a plurality of moving contacts 17 to 21 which, as will be seen later, are spring-loaded into en gagement with individual turns at locations which are physically on the same side of the coil IS. The output of the device [4 contains similar contact fingers 22 to 26, supported from conductive support [6a, which are in engagement with individual coil turns on the opposite side of coil 15 from the side which receives contact The normal current flow in the circuit of FIG. I will then be from terminal [0 through interrupter 12, through all of input fingers l7 to 21 and then through all of the output fingers 22 to 26 of the terminal ll. The current flow from contacts 17 to 21 to contacts 22 to 26 for a given coil turn will be in one direction over the top of the turn and the opposite direction through the bottom of the turn. Thus, the entire winding 15 is, in effect, split up into parallel conductors with no current flowing around the coil as in an inductive device. Thus,

the coil 15 has no intentional impedance. The various contact fingers 17 to 26 are then arranged. as will be later seen, to be blown off by the current flow through the sections of the coil. Note, however, that any other desired operating mechanism can be provided to operate the individual contact fingers I7 to 26. If the blowoff mode is used when a short-circuit occurs. the contact fingers 17 to 26 will blow off at some level determined by respective contact pressure springs. ()nce open, each finger may be held open by an individual latch. Note that the blow open action will be cumulative in that. as soon as one finger blows off, more current must flow in the remaining parallel paths to force the sequential operation of each of the contact fingers 17 to 26. The springs may further be adjusted to ensure a particular sequence of operation such that contacts I7 through 2] blow off in sequence. contacts 22 through 26 blow off next in sequence. By properly controlling the number of turns and the geometry of coil 15, arcing at the individual contact fingers can be eliminated, or minimized to a point where the arc can be easily extinguished.

After the circuit has been operated and the circuit breaker I2 is opened. the contact fingers can be reset by spring pressure of their biasing springs when the individual latches of contacts 17 to 26 are removed.

FIGS. 2, 3 and 4 schematically illustrate a conventional type of circuit interrupter which has been modified to receive a currentlimiting device of the general type shown in FIG. 1. Referring first to FIG. 2, there is schematically illustrated a circuit breaker ofa generally conventional type and which has a molded support housing which carries tubular conductive terminals 41 and 42 which have tulip type disconnect contact assemblies 43 and 44 connected thereto by webs 45 and 46, respectively. The tulip type disconnect contacts 43 and 44 are then engageable with appropriate stationary conductors such as the

stationary conductors

47 and 48, respectively, which may be the stationary disconnect contacts contained in the interior of a conventional switchgear housing. Note that the breaker shown in FIG. 2 is of the type that is conventionally racked in and out of its switchgear cubicle. Conventional auxiliary equipment is provided for the circuit breaker such as the

current transformers

50 and 51 which encircle the lower terminal of the device.

The lower elongated terminal 41 is then connected to a movable contact arm which is pivotally mounted on stationary pivot 61 and which is operated by rotation about pivot 61 by a conventional operating mecha nisrn 62. Operating mechanism 62 is equivalent to mechanism 13 in FIG. 1. The movable contact 60 then cooperates with stationary contact elements, such as contact fingers disposed beneath contact springs 63 to 66 and by an arcing contact 67. These various contact elements make sliding contact with contact arm 60 to complete a current path to the stationary conductive member 68.

All of the foregoing structure described in connection with FIGS. 2 and 4 is of any desired conventional type and is simply intended to show a circuit breaker which can be of the type schematically shown for the circuit interrupter 12 of FIG. 1.

In accordance with the invention, the current conducting member 68 of FIG. 2 is connected as by brazing or bolting, or the like, to the terminal 70 of the multi-helica] winding 71.

The helical winding 71 of FIG. 2 is also shown in FIGS. 3 and 4 along with its input conductor 70. It will be seen from FIGS. 3 and 4 that the winding 71 is a tenturn winding and has an output conductor 72 which is appropriately connected as by bolting or brazing, or the like, to the conductive support 42 of the circuit breaker.

The conductive member 68 of the circuit breaker of FIG. 2 has an elongated conductive plate member 80. shown in FIGS. 2, 3 and 4, which serves as a support for a plurality of contact fingers to 99 which. as can be best seen from FlG. 2, are pivotally mounted on a pivotal shaft connected with contact finger 90.

Note that the pivot I00 can be a common pivot for each of contact fingers 90 to 99 or, alternatively, each contact finger can have its own pivotal support cooperating with an extending support finger of conductive body 80. Note further that the pivotal connection between the member 80 and the fingers 90 to 99 is a current carrying connection which can be conventionally ac hievcd in any desired manner as by conductive washers and the like. Thus. in FIG. 4 and for the case of contact finger 91 there is shown a silver washer 9Iu which makes good electrical connection between the finger 9l and the extending comb-like recess of elongated conductive plate 80. A belleville type washer 91b presses finger 91 against the washer 91a.

It will be noted that each of the fingers 90 through 99 is arranged to engage the lateral side of each respective turn of the coil 71. Moreover, each of the contact fingers is provided with a biasing spring, such as the biasing spring 110, shown for finger 90, where the spring 0 is carried on bracket 111. A similar compression spring is provided for each of the contact fingers 91 through 99 as schematically illustrated in FIG. 3, where these springs are supported from the block 68.

The bottom of contact fingers 90 through 99 are then provided with latch rollers, such as the latch roller 120, shown in FIG. 2 for finger 90, where the latch roller cooperates with pivotally mounted latch 121 which is pivoted on a fixed support shaft 122. Latch I2! is further provided with a tension spring I23 which tends to normally rotate the latch clockwise and into engagement with a reset bar and stop member 124. Thus, the bar 124, which is movable from the position shown and to the left and in the direction of arrow 125 of FIG. 2, may be a single bar which operates all of the latches similar to latch 121, which cooperate with the fingers 91 to 99.

It can now be understood that when the latch 121 and the other similar latches are in the position shown, that the spring 110 and finger 90 along with the other contact fingers will be pressed into engagement with the respective turns of windings 71. Note, however, that if the contact fingers 90 to 99 are operated to an open position by rotation in a clockwise direction about pivot 100, that the latches such as latch 121 will rotate clockwise to the stop position defined by bar 124 in order to latch the individual latch rollers, such as roller 120 of FIG. 2.

A substantially identical contact finger configuration is provided on the opposite side of winding 71 and is shown in FIG. 3 by the contact fingers 130 to 139. These contact fingers are mounted and biased and latched in a manner substantially identical to that described above in connection with fingers 90 to 99. Thus, the fingers are pivotally mounted on pivots such as pivot 140 which are current carrying pivots, and are spring biased into engagement with each of the turns of the coil by biasing springs, such as the biasing spring 141 carried from bracket 142 carried on member 42.

Latches such as latch 143 are similarly provided to latch the latch rollers, such as latch roller 144 of the contact fingers 130 to 139, where the latch 143 and similar latches are biased counterclockwise about their support pivots, such as pivot 145 by tension springs 146. A reset stop bar 147 is also provided which is movable in the direction of arrow 148 in order to allow reset of the individual contact fingers 130 to 139 under the influence of their biasing springs, such as spring 141.

The current-limiting device shown in FIGS. 2 and 3 is operated in response to the current flow through the individual contact fingers 90 through 99 and 130 through 139, where these fingers are opened due to the magnetic blow-off effect of the current. Thus, the nor mal current path through the entire assemblage of FIGS. 2 and 3 will be from terminal 47 through conductor 41, movable contact 60, stationary contact elements 63, 64, 65. 66 and 67, into the

conductive members

68 and 80 and then into the parallel conductive fingers 90 through 99 and then in parallel through the individual turns of coil 71. The parallel flowing currents exit through the

parallel fingers

130 and 139 and into terminal 42 and then terminal 48. The current path across the coil 71 is such that the current divides above and below the coil to flow in parallel around the upper and lower half loops formed by the turns of the coil.

The current flow, for example, through finger 90 will then be upwardly and then changing to the left to enter the right-hand side of the turn of coil 71 which is engaged by contact 90. This change in current direction then forms a blowoff path which creates a force which would tend to rotate the contact finger 90 (as well as fingers 91 to 99) in a clockwise direction and in opposition to the biasing force spring 110. Under normal current conditions. the biasing force of spring 110 is sufficiently high to maintain good pressure contact but, when the current increases, as due to a short circuit in the circuit being protected by the device, the magnetic forces created are sufficiently strong to rotate fingers to 99 to an open position, where they are latched by their respective latches, such as latch 12]. A similar blow-ofi path is formed for each of contacts 130 to 139, so that they too will be blown off when the current carried through these contact fingers becomes sufficiently high.

Preferably, the biasing springs, such as biasing springs and 141, are so arranged that the fingers blow off in a sequential manner. Thus, the biasing forces can be so arranged that contact finger 90 will be the first to open when a predetermined current magnitude appears. Then fingers 91 through 99 will blow off in sequence. This will then insert the first turn of the inductive winding 71 into the circuit to cause a relatively small inductive impedance to appear in the circuit which will tend to limit current. At the same time, an increased current will flow into the remaining closed fingers so that the next fingers will open, such contact fingers through 139 in sequence. thereby to insert successive turns into the circuit which is being protected. Ultimately, each of the contact fingers will be opened so that the full coil 71 is inserted in series with the circuit being protected in order to limit the current flow in the circuit.

FIG. 5 shows an alternate arrangement for mounting and latching the contact fingers and is shown in connection with contact finger 90. Thus, in FIG. 5 an angle member is secured to plate 80 or may be otherwise secured, for example, to the support molding 40 and carries the shaft 122 which pivotally mounts the various latches, such as latch 12].

The biasing spring 123 for latch 121 is shown in FIG. 5 as a compression spring which is seated at one end on the bracket 161 and at its other end on the interior surface of latch 121, thereby to bias latch 121 in a clockwise direction and against stop bar 124. Clearly, other support arrangements could be provided for supporting and biasing the latches such as latch 121.

The novel invention has been described above in connection with a helically wound inductance coil where current flow through the coil from the contact fingers is along the winding length. FIGS. 6 to 8 schematically illustrate a further embodiment of the invention in connection with a spirally wound coil where current flow between the contact elements is perpendicular to the length of the winding, with the contacts engaging the winding at its end surfaces rather than its lateral surfaces as in FIGS. 2, 3 and 4.

Thus, in FIGS. 6, 7 and 8 there is shown a two-turn spiral winding which has terminal ends 171 and 172 (FIG. 7).

As best shown in FIGS. 6 and 8, contact means in cluding contact pairs 173174, 175-176, 177-178 and 179-180 are electrically connected to and supported by

conductive members

181 and 182. Terminal 172 is electrically and mechanically connected to conductive member 182 while terminal 171 is electrically and mechanically connected to conductive member 181. Thus, the terminals of coil 170 are connected so that the coil is in series between

conductive members

181 and 182 which are, in turn, appropriately connected to a circuit interrupting device as in the case of FIGS. 2. 3 and 4. The individual contact members 173 to are then arranged in a manner similar to that described, for example, in connection with FIGS. 3, 4 and 5 where, for example, the contacts are associated with appropriate biasing springs and latches, and the like.

During operation, the individual contact elements engage the ends of respective coil portions so that the electrical winding is simply a conductive shunt between the

conductive members

181 and 182. However, when the electrical contacts 173 to 180 open, the inductance of the coil 170 is inserted in series with

conductive members

181 and 182 to introduce impedance into a circuit which could, in turn, limit current rise in the cireuit.

Referring next to FIGS. 9 to 14, there is disclosed therin the additional subject matter of this continuation-inpart application. Referring first to FIG. 9. there is schematically illustrated a spirally wound coil 200 similar to the spirally wound arrangement of the em bodiment of FIGS. 6, 7 and 8, where the spirally wound coil 200 contains 2% turns for illustrative purposes only. Each side of the spirally wound coil 200 then receives opposing contacts, shown as contacts 201 to 206 on one side and opposing contacts 207 to 212, respectively, opposing contacts 201 to 206 on the opposite side of the spiral winding 200. Each of contacts 201 to 206 are then connected to one another and are con nected to a first terminal 220 and, similarly, contacts 207 to 212 are connected to one another and to a second terminal 221. The inside end of coil 220 is connected to terminal 220 and the outside end of coil 200 is connected to terminal 221.

As will be later disclosed, the contacts 201 through 212 are provided with suitable adjustable biasing springs. such that the contacts will blow open in a sequence which preferably introduces the inductance of winding 200 one-half turn at a time. Thus, under normal current-carrying conditions, all of contacts 201 to 212 engage opposite sides of spiral 200 so that no induetance is interposed between

terminals

220 and 221. However, upon the occurrence of a fault current. the contacts 201 to 212 will open in the sequence: 201, 202, 203, 204, 205. 206, 210. 208, 211,209, 212 and 207. The above sequence of operation permits the gradual insertion of the inductance of the coil 200 into the circuit to avoid the high induced voltages in the circuit and across the device.

An importance feature of FIG. 9 is that a magnetic core 230 can be formed around the winding in order to increase the inductance of the winding. Note that the magnetic core can be formed of conventional steel laminations or the like.

FIGS. 10 to 14 illustrate the manner in which the device of FIG. 9 can be manufactured to form a com pletely self-contained unit which is interchangeable and replaceable with standard fuse-type devices. Referring now to FIGS. 10, 11 and 12, the self-contained device has extending

terminal bus members

240 and 241 which may have terminal openings fixed on the same spacing as the terminal opening of a conventional highcurrent fuse which can be replaced by the conventional novel current-limiting device.

Each of

busbars

240 and 241 are bolted to conductive angle members 242-243 and 244-245, respectively, by bolts such as

bolts

246 and 247. The entire assembly is then supported between the

flanges

242 and 245. Each of the flanges or angles 242 to 245 are supported relative to one another by suitable insulation spacers best seen in FIG. 11 as

typical insulation spacers

250 and 251 which are fixed to the various angles by bolts 252-253 and 254-255, respectively. Similar sets of spacers are disposed below

spacers

250 and 251

such spacers

256 and 260 in the view of FIG. 14.

Nuts

261 and 262 are shown in FIG. 10 for the

spacers

256 and 260, respectively (FIG. 14).

Spacers

251, 253, 256 and 260 receive an insulation plate 270 (FIGS. 11, 12 and 14) which in turn receives the multi-turn spiral winding 271 which is rigidly clamped into a central opening in the insulation plate 270. One end of spirally wound winding 271 has a terminal portion 272 (FIGS. 11 and 12) which is connected to the conductive angle 243 by the bolt connector 273. The opposite end of winding 271 and the interior end in the spiral winding is provided with an extension 275 (FIG. 11) which is connected to the conductive angle 245 by bolts 276 and 277 (FIGS. 10 and 11 Thus, the spiral winding 271 is connected in series between

insulated terminals

240 and 241.

The winding is further surrounded by transformer steel lamination packs 280 and 281 which are supported by suitable angle supports shown as angle supports 282-283 and 284-285 for lamination packs 280 and 281, respectively. The transformer iron laminations increase the inductance of the spiral winding 271 as desired.

Four packages of contact finger assemblies are then disposed within the self-contained device to make engagement and disengagement between

angles

242 and 243 and the left-hand side of winding 271, and angles 244 and 245 and the right-hand side of winding 271 in FIG. 1 1. Thus, contact assembly packages 290 and 291 are bolted to

angles

242 and 243 respectively while contact packages 293 and 294 are connected to

angles

244 and 245 respectively.

FIG. 10 shows bolts 295 to 298 which serve to hold contact package 293 in position and further shows bolts 299 to 302 which serve to hold the package 294 in position. Similar bolts, such as bolts 306 and 307 (FIG. 11) secure package 290 (FIG. 12) in position. Another similar arrangement of bolts (not shown) holds package 291 in position.

Each of the individual packages of contacts 290 to 293 are identical in construction and are shown in detail in FIG. 13 in connection with package 294. Each package contains a plurality of pivotally movable contact fingers shown in FIGS. 12 and 13 as contact fingers 310 to 313 which are each pivotally mounted on a pivot pin 314. The pivot pin 314 is carried from sta tionary conductive plates 315 to 319 which extend from a common conductive rear surface 320 (FIG. 12) whereby the plates 315 to 319 serve as the teeth of a comb-shaped arrangement having the spine 320. The same comb-teeth plates 315 to 319 also support a second pivot pin 321 which carries individual latch members 322 to 325 which respectively act to latch contact fingers 310 to 313 as will be later described.

Each of the contact fingers 310 to 313 have an extending region for receiving a respective biasing spring. such as the biasing spring 330 in FIG. 12 for finger 310 and spring 331 in FIG. 14 for finger 313. Each of the contact fingers will obviously have a spring such as springs 330 and 331 which tend to bias the contact strongly counterclockwise in FIG. 12 and into engagement with the edge of a respective winding portion which serves as a stationary contact of the winding 271. Note that FIG. 12 shows the contact finger 310 in its opened position.

The latch members 322 to 325 are similarly provided with biasing springs. such as biasing spring 340 in FIG. [2 for latch 322 where the spring 340 extends to the corresponding latch 341 in package 290. Thus. each of latches 322 to 325 are biased in a clockwise direction with the latch stopping against the underside of the contact finger to the latching position shown which latches the corresponding contact fingers open once the contact fingers have been moved to their open position it will be noted in FIG. 14 that the biasing spring 340 for latch 322 and similar springs 350. 351 and 352 for latches 323. 324 and 325 are also shown.

In order to close the contacts. means (not shown I are provided for rotating latches 322 to 325 in a counter clockwise position. thereby permitting the contact firlgers 3") to 313 to move counterclockwise under the influence of their biasing springs such as spring 330.

In order to obtain the desired sequential operation of the contacts. their individual contact spring forces are easily adjustable from a region external of the device. with each ofthe springs. such as spring 330. being supported from a bracket 360 (FIGS. 10 and 12) which has a window 361 which exposes the adjustment screws 362 to 365 for each of the contact springs of the pack age. Similar windows. such as window 370. are pro idcd for each of the other packages in the various angles.

ln operating the device of FIGS. 10 to 14. it will be noted that a blowoff current carrying path is formed from each terminal through each contact and into the spiral winding 27]. Thus. when current through the device exceeds a given value. the contact will tend to be moved by magnetic forces to a disengaged position. By appropriately controlling the biasing force of springs 336 for each of the contacts. and because each contact will carry an increasing current after a preceding contact has opened. the contacts can be arranged to open sequentially. thereby to insert the inductance of winding 27] one-half turn at a time with the contacts latching open once they reach their fully open position. The currenbcarrying device may then be restored to service by releasing each of the latches of the contact fingers so that winding 271 will in effect be short circuited by the current path through opposing contact fingers of the opposing packages 290-293 and 291-294.

Although the present invention has been described in connection with preferred embodiments thereof. many other variations and modifications will now become ap parent to those skilled in the art. It is preferred. therefore. that the present invention be limited not by the specific disclosure herein. but only by the appended claims.

The embodiments of the invention in which an exclu sive privilege or property is claimed are defined as follows.

l. A sclt contained current-limiting device compris ing in combination:

a winding having a plurality of insulated turns and having first and second ends;

a first and second plurality of contacts connected to said first and second ends respectively. and movable into and out of engagement with respective se lected regions of said plurality of insulated turns;

first and second extending terminals for said device;

said first plurality of contacts connected to said first terminal; said second plurality of contacts con nected to said second terminal;

biasing means for biasing each contact of said first and second plurality of contacts into engagement with said selected regions of said turns. whereby a current path is formed essentially laterally through said plurality of turns. whereby the inductance of said plurality of turns is not connected between said first and second terminals;

operating means for moving at least selected contacts of said first and second plurality of contacts to a disengaged position relative to said selected regions when the current flow between said first and second terminals exceeds a predetermined value; and

latch means for latching said contacts in a disengaged position after their movement thereto.

2. The device of claim 1 wherein said first and second terminals are generally coaxial with one another and are spaced from one another by a given dimension. whereby said device is interchangeable with a preexisting fuse device.

3. The device of claim 1 wherein said operating means at least includes the magnetic field produced by the current flow through said plurality of contacts. whereby said current path applies a blow-off magnetic force for said contacts.

4. The device of claim 2 wherein said first and second terminals each comprise rectangular has members hav ing terminal openings therein.

5. The device of claim 4 wherein said plurality of first and second contacts. said biasing means. said winding. and said latch means are physically supported from said first and second terminals.

6. The device of claim 5 wherein said first plurality of contacts are fixed to said first terminal. and wherein said second plurality of contacts are fixed to said second terminal. and which further includes insulation spacer means for physically connecting said first and second terminals to one another and for physically supporting said winding.

7. The device of claim I wherein said winding is spirally wound and wherein said first and second pluralities of contacts engage respective opposite sides of said winding.

8. The device of claim 7 wherein said first plurality of contacts are fixed to said first terminal, and wherein said second plurality of contacts are fixed to said second terminal. and which further includes insulation spacer means for physically connecting said first and second terminals to one another and for physically supporting said winding.

9. The device of claim 1 wherein each of said plurali ties of contacts consist of identical assemblies of identical contacts.

10. The device of claim 8 wherein each of said pluralities of contacts consist of identical assemblies of identical contacts.

1], The device of claim 1 which further includes magnetic core means mounted on said winding and magnetically coupled thereto. thereby to increase the inductance of each of said turns.

12. The device of claim 8 which further includes magnetic core means mounted on said winding and magnetically coupled thereto. thereby to increase the inductance of each of said turns.

13. A current-limiting device comprising, in combination:

a winding having a plurality of insulated turns;

a first and second plurality of contacts movable into and out of engagement with respective selected regions of said plurality of insulated turns;

first and second terminals for said device;

biasing means for biasing each contact of said first and second plurality of contacts into engagement with said selected regions of said turns, whereby a current path is formed essentially laterally through said plurality of turns, whereby the inductance of said plurality of turns is not connected between said first and second terminals;

operating means for moving at least selected contacts of said first and second plurality of contacts to a disengaged position relative to said selected regions when the current flow between said first and second terminals exceeds a predetermined value;

and magnetic core means mounted on said winding and magnetically coupled thereto, thereby to increase the inductance of each of said turns.

[4. The device of claim 13 wherein said winding is spirally wound and wherein said first and second pluralities of contacts engage respective opposite sides of said winding.

15. A current-limiting device comprising in combination:

a winding having a plurality of insulated turns;

first and second insulated terminals for said device;

said first plurality of contacts connected to said first terminal; said second plurality of contacts connected to said second terminal;

biasing means for biasing each contact of said first and second plurality of contacts into engagement with said selected regions of said turns. whereby a current path is formed essentially laterally through said plurality of turns, whereby the inductance of said plurality of turns is not connected between said first and second terminals;

operating means for moving at least selected contacts of said first and second plurality of contacts to a disengaged position relative to said selected regions when the current flow between said first and (all second terminals exceeds a predctemiined value;

said winding being spirally wound; said first and second pluralities of contacts engaging opposite sides of said winding.

16. The device of claim 15 wherein each of said pluralities of contacts consist of identical assemblies of identical contacts.

17. The device of claim 14 which further includes latch means for latching said contacts in a disengaged position after their movement thereto.

18. The device of claim 15 which further includes latch means for latching said contacts in a disengaged position after their movement thereto.

19. The device of claim 1 wherein said operating means operates said contacts in a predetermined sequence, thereby to sequentially insert the turns of said winding in series between said first and second terminals.

20. The device of claim 19 wherein said operating means at least includes the magnetic field produced by the current flow through said plurality of contacts, whereby said current path applies a blow-off magnetic force for said contacts.

21. The device of claim 8 wherein said operating means operates said contacts in a predetermined sequencc. thereby to sequentially insert the turns of said winding in series between said first and second terminals.

22. The device of claim 10 wherein said operating means operates said contacts in a predetermined sequence, thereby to sequentially insert the turns of said winding in series between said first and second terminals.

23. The device of claim ll wherein said operating means operates said contacts in a predetermined se quence, thereby to sequentially insert the turns of said winding in series between said first and second terminals.

24. The device of claim 13 wherein said operating means operates said contacts in a predetermined sequence, thereby to sequentially insert the turns of said winding in series between said first and second terminals.

25. The device of claim 15 wherein said operating means operates said contacts in a predetermined sequence. thereby to sequentially insert the turns of said winding in series between said first and second terminalsi

Claims

1. A self-contained current-limiting device comprising in combination: a winding having a plurality of insulated turns and having first and second ends; a first and second plurality of contacts connected to said first and second ends respectively, and movable into and out of engagement with respective selected regions of said plurality of insulated turns; first and second extending terminals for said device; said first plurality of contacts connected to said first terminal; said second plurality of contacts connected to said second terminal; biasing means for biasing each contact of said first and second plurality of contacts into engagement with said selected regions of said turns, whereby a current path is formed essentially laterally through said plurality of turns, whereby the inductance of said plurality of turns is not connected between said first and second terminals; operating means for moving at least selected contacts of said first and second plurality of contacts to a disengaged position relative to said selected regions when the current flow between said first and second terminals exceeds a predetermined value; and latch means for latching said contacts in a disengaged position after their movement thereto.

2. The device of claim 1 wherein said first and second terminals are generally coaxial with one another and are spaced from one another by a given dimension, whereby said device is interchangeable with a pre-existing fuse device.

3. The device of claim 1 wherein said operating means at least includes the magnetic field produced by the current flow through said plurality of contacts, whereby said current path applies a blow-off magnetic force for said contacts.

4. The device of claim 2 wherein said first and second terminals each comprise rectangular bus members having terminal openings therein.

5. The device of claim 4 wherein said plurality of first and second contacts, said biasing means, said winding, and said latch means are physically supported from said first and second terminals.

6. The device of claim 5 wherein said first plurality of contacts are fixed to said first terminal, and wherein said second plurality of contacts are fixed to said second terminal, and which further includes insulation spacer means for physically connecting said first and second terminals to one another and for physically supporting said winding.

7. The device of claim 1 wherein said winding is spirally wound and wherein said first and second pluralities of contacts engage respective opposite sides of said winding.

8. The device of claim 7 wherein said first plurality of contacts are fixed to said first terminal, and wherein said second plurality of contacts are fixed to said second terminal, and which further includes insulation spacer means for physically connecting said first and second terminals to one another and for physically supporting said winding.

9. The device of claim 1 wherein each of said pluralities of contacts consist of identical assemblies of identical contacts.

11. The device of claim 1 which further includes magnetic core means mounted on said winding and magnetically coupled thereto, thereby to increase the inductance of each of said turns.

12. The device of claim 8 which further includes magnetic core means mounted on said winding and magnetically coupled thereto, thereby to increase the inductance of each of said turns.

13. A current-limiting device comprising, in combination: a winding having a plurality of insulated turns; a first and second plurality of contacts movable into and out of engagement with respective selected regions of said plurality of insulated turns; first and second terminals for said device; said first plurality of contacts connected to said first terminal; said second plurality of contacts connected to said second terminal; biasing means for biasing each contact of said first and second plurality of contacts into engagement with said selected regions of said turns, whereby a current path is formed essentially laterally through said plurality of turns, whereby the inductance of said plurality of turns is not connected between said first and second terminals; operating means for moving at least selected contacts of said first and second plurality of contacts to a disengaged position relative to said selected regions when the current flow between said first and second terminals exceeds a predetermined value; and magnetic core means mounted on said winding and magnetically coupled thereto, thereby to increase the inductance of each of said turns.

14. The device of claim 13 wherein said winding is spirally wound and wherein said first and second pluralities of contacts engagE respective opposite sides of said winding.

15. A current-limiting device comprising in combination: a winding having a plurality of insulated turns; a first and second plurality of contacts movable into and out of engagement with respective selected regions of said plurality of insulated turns; first and second insulated terminals for said device; said first plurality of contacts connected to said first terminal; said second plurality of contacts connected to said second terminal; biasing means for biasing each contact of said first and second plurality of contacts into engagement with said selected regions of said turns, whereby a current path is formed essentially laterally through said plurality of turns, whereby the inductance of said plurality of turns is not connected between said first and second terminals; operating means for moving at least selected contacts of said first and second plurality of contacts to a disengaged position relative to said selected regions when the current flow between said first and second terminals exceeds a predetermined value; said winding being spirally wound; said first and second pluralities of contacts engaging opposite sides of said winding.

21. The device of claim 8 wherein said operating means operates said contacts in a predetermined sequence, thereby to sequentially insert the turns of said winding in series between said first and second terminals.

23. The device of claim 11 wherein said operating means operates said contacts in a predetermined sequence, thereby to sequentially insert the turns of said winding in series between said first and second terminals.

25. The device of claim 15 wherein said operating means operates said contacts in a predetermined sequence, thereby to sequentially insert the turns of said winding in series between said first and second terminals.