US2166590A - Electric circuit breaker - Google Patents

Description

July 18,'51939. H. A. HIDDE NIJLAND 1'2,166,590

ELECTRIC CIRCUIT BREAKER 3 Sheets-Sheet 2 July 18, l939- H. A. HIDDE NIJLAND ELECTRIC CIRCUIT BREKER Filed oct. so, 1937 MY 18, 1939- H. A. HIDDE NIJLAND 2,166,590

ELECTRIC CIRCUIT BREAKER Filed Oct. 50, 1837 3 Sheets-Sheet 3 Patented July 18, 1939 UNITED STATES PATENT oFFicE Application October 30, 1937, Serial No. 172,029 In the Netherlands November 17, 1936 3 Claims.

The invention relates to a circuit-breaker for high voltage such'as is used in electric power stations and substations for the distribution of electricity and the protection of the distributing 5 networks, more especially to a circuit-breaker, in which the contact make and break element, comprising fixed contacts and a movable contactknife cooperating therewith, is mounted in a metal tank filled or adapted to be filled with insulating fluid, for instance mineral oil.

Circuit-breakers, for instance automatic switches, change-over switches, hand switches and the like, which have to switch often and under unfavorable conditions and whose contacts .15 and contact knives are thereby liable to heavy wear and tear, should be adapted to readily be rendered dead in order that they may be inspected and repaired. Up till now such circuitbreakers are therefore connected with the live 2() network (bus bar System, overhead line, cable) through other switches, s'o called isolating switches. These isolating switches were only used for disconnecting the main circuit-breaker from the network, but only after the main cir- 27, cuit-breaker had opened the circuit, as they are ordinarily not adapted to switch while under i load. As viewed from a purely electrical standpoint, such isolating switches do not serve any purpose. They render the switchgear compligg cate, bulky and expensive.,

The invention has for its object to avoid the necessity of using isolating switches, which up till now are indispensable and provides a main circuit-breaker (by which is meant a switch 3;, adapted to make and break contact under normal load or under overload), the composite parts of which can be inspected or repaired, without the necessity of disconnecting the switch from the network by means of separate isolating switches. The invention consists in connecting the xed contacts of the circuit-breaker to leading-in conductors passed through insulators in the wall of the tank in such a manner that the entire contact make and break element can be removed from the tank and reintroduced, while vthe leading-in conductors are alive. The leading-ln conductors may therefore be connected to the network without interposing isolating switches. A secondary advantage thereof is that no accidents can be caused when the wrong isolating switch is operated, which in practice sometimes occurs. When the main circuit-breaker is to be inspected, the contact make and break element is to be entirely removed .from the tank so as to u be remote from parts that are live. Switchgear composed of such circuit-breakers is'simple and cheap and, besides, occupies relatively `little space.

In accordance with the invention, each of two fixed contacts of the circuit-breaker may be electrically connected and mechanically secured to a contact-socket engaging either a plug provided at that end of the corresponding leading-in conductor, which extends into the tank, or engaging the plug-shaped end of said conductor. f

It is especially advantageous for the metal tank to be composed of two vertical tubular casings communicating near their top ends, the leading-in conductors being passed into said casings through or in the vicinity of the bottoms thereof. Since with this construction the leading-in conductors are each provided inv an individual casing and in the lower portions of the tank, their ends will remain comparatively far below the lowered liquid level (provided that the tank is iilled with an insulating liquid) after the contact make and break element has been removed.

Furthermore, and in accordance with the invention, the xed contacts may be mounted in the axis of one of the tubular casings and secured to an insulating bush provided within said casing, whereas the contact-knife may be arranged and be movable in the axis of said casing. This offers the advantage that the contact make and break element may have a substantially circular external cross-section throughout, so that the electric'eld distribution in the circuit-breaker may be substantially radial, whereby a uniform load of the dielectric can easily be obtained. With a view thereto, the tubular casing may surround the contact make and break element with relatively little clearance, so that only a small amount of insulating material is required. As a consequence, the circuit-breaker is relatively cheap to make and is not very dangerous in case of lire, provided that oil is used as an insulating fluid.

Another advantage of said arrangement is that the circuit-breaker can be made so as to allow the contact-knife to be withdrawn lengthwise from the tubular casingor inserted thereinto, while the fixed contacts are alive. This construction 'permits of ready change of the function of the circuit-breaker. For instance, instead of an automatically or manually movable contact-rod, a thin, conducting wire tightened between two contact rings and adapted to melt when overloaded may be used for bridging the fixed contacts. The circuit-breaker can, in that case, also serve as a fuse, and be used, for instance, for protecting small transformers. Moreover, the possibility of entirely removing the contact-knife from the tank is of great importance from the standpoint of safety. If it is required to overhaul an apparatus or a cable at the outgoing side of the circuit-breaker, one need only remove the contact-knife (or knives) from the tank to make perfectly sure that the contacts are disconnected from each other. l

To illustrate the above, reference is had to the drawings, which by way of example show some embodiments of the invention. In the drawings:

Fig. 1 is a vertical sectional view of a circuitbreaker in accordance with the invention.

Fig. 2 is part of a sectional view corresponding to Fig. 1, during the withdrawal from the tank of the inner parts of the circuit-breaker.

Figs. 3 and 4 are a front elevation and a side elevation respectively, of a triple-pole circuitbreaker connected to a bus bar system and to a cable, and

Figs. 5 and 6 are an elevation and a crosssectional view respectively, of a melting fuse, drawn to an enlarged scale.

In Fig. 1, the numeral designates a rodshaped contact-knife adapted to cooperate both with a xed contact 2 having spring contact fingers 3 and with a fixed contact 4 having spring contact fingers 5, the fingers 3 and 5 being arranged in circular series around the contact-rod I. The contact-rod I is mounted in the axis of a metal tubular casing 6 and is adapted for lengthwise movement and for withdrawal from and' reinsertion into the tank'of the circuitbreaker by means of a rod 1 arranged in alignment vwith the contact-rod I and connected thereto through an insulator 8. The xed contact 2 is directly connected, both electrically and mechanically, to a contact-socket 9 having spring contact fingers I0 engaging a plug shaped end II of a ieading-in conductor I2 which is passed through an insulator in the bottom of the tubular l casing 6 and 'connected with its other end to a distributing bus bar I3. The xed contact 2 and the contact-socket 8 are mounted on an insulating support I4, secured by means of an insulating and threaded sleeve I5 to an insulating bushing I6 extending through substantially the entire length of the tubular casing 6.' i

The fixed -contact 4 has a screw connection with one end of a sleeve I1 of highly conductive metal fitting into the bushing I6, the other end thereof being connected through a horizontal conductor I8 to the top end of a second conductive sleeve |9. The latter is surrounded by an insulat- .ing bushing 20 mounted in a tubular metal casing 2|. The-conductive sleeve I9 is provided at its lower endwith a contact-socket 22 having a circular series of spring contact fingersv 23 engaging the plug-shaped end of a leading-in conductor 25, which passes through the bottom of the casing 2|, and whose other end extends into a cable junction box 26. The horizontal conductor I8 is surrounded by an insulating bushing 21 and is.

mounted in a receptacle 28 interconnecting the tubular casings 6 and 2|. Provided in this receptacle 28 is -a current transformer of the ring type 29 for protective or metering purposes. The current transformer of the ring type in the receptacle may be substituted by a current transformer having a primary coil, or by a relay having a high tension coil.

The metal tank of the circuit-breaker, consisting of the vertical casings 6 and 2| and the connecting receptacle 28, is closed at the topside by means of a loose insulating plate 30, which itself is covered by a metal plate 3|. Said plates are supported by bosses 30a of the wall of receptacle 28. The bush I6, the ilxed contacts 2 and 4, the conductive sleeve I1 and the contactsocket 9 are secured to the plates 30, 3 I, by means of an insulating tube 32, one end of which has a screw connection with the sfixed contact 4, the other end passing through the plates 30, 3|. 'Ihe latter end is provided with a screw cap 33. An

insulating sleeve 34, which projects into a circular groove 35 of the plate 30, and holds the bushing |6, the sleeve |1, the fixed contacts 2 and 4 and the contact-socket I9 in their proper places, when the screw cap 33 is tightened.

Said cap also serves to guide the rod 1 secured to the contact-rod In a similar manner, the bushing 20, the sleeve I9 and the contact-socket 22 are secured to the plates 30,.3| by means of an insulating tube 36. The lower end of this tube is screwed into the contact-socket 22, whereas the topend passes through the plates 30, 3| and is engaged by a screw cap 31. An insulating sleeve 38 extending into an annular groove 39 of the plate 30 holds the bushing 2|),

` the sleeve I9 and the contact-socket 22 in their proper places. The tank of the circuit-breaker isi closed by a. cover 40, through which project only the screw cap 33 and the operating rod 1.

Mounted on the cover is a box 4| shown in dash lines) enclosing an operating mechanism.

After removal of the cover, the interior parts of the circuit-breaker, with the exception of the leading-in conductors I2 and 25, can be hoisted from the tank by means of an eye 42 (Fig. 2), without it being necessary rst to release any connection. If the tank is lled with an insulating liquid, the level of the liquid will be lowered through a considerable distance owing to the withdrawal of the interior parts- (Fig. 2). However, since the leading-in conductors I2 and 25 are mounted in the lower portions of the tubular casings 6 and 2|, they will even then remain a suilicient distance below the liquid level. When the interior parts and especially the contactsockets of the circuit-breaker are to be inspected, it is not necessary for the busbar and the cable to be rendered dead. Consequently, the usual isolating switches at the incoming and the outgoing side of the main circuit-breaker are redundant.

In accordance with Figs. 3 and 4, three circuitbreakers in accordance with the invention are combined to form a triple-pole circuit-breaker. 'I'hrough a common cable junction box 43, the circuit-breaker is connected to a triple-conductor cable.

The circuit-breaker is mounted on a chamber 44 containing a triple-busbar system 45. the cover 4|) and the operating mechanism may be common to the three unipolar circuit-breakers.

I t is not necessary for each of the contact make and break elements of a multipolar circuitbreaker to be mounted in an individual tank; they may also be accommodated in a common tank. Furthermore, it is obvious that other arrangements may be used. The leading-in conductors |2 and/or 25 could also pass laterally into the tubular casings 6 and 2|, respectively. 'Ihe circuit-breakers may be arranged horizontally. Furthermore, they can be provided in the ordinary manner with a -gas vent, an oil level gauge and other auxiliaries. When the contact-rod has been withdrawn from the circuit-breaker, it is Also Y,switchable fuse.

very easy for an earthing apparatus or for a voltage -indicator to be inserted. Consequently, it is not necessary to make' special provisions for this purpose, as hitherto required. Y

The contact-rod in accordance with Figs. and 6 consists of two parallel rods Il of insulating material, which on either end carry a common contact ring 41, 4l adapted to engage the contact fingers I, 5 of the fixed contacts 2, 4 diagrammatically shown in dash lines. The contact rings are interconnected' by a thin, conductive wire Il adapted to melt when carrying an excessivecurrent. If, therefore, the circuit-breaker is provided with such a contact-rod, it can be used as a Since the contact-rod can be withdrawn while the xed contacts are under tension, the fuse wire can easily be renewed.

The special construction of a circuit-breaker in accordance with the invention enables one and the same bay of a switch-gear embodying the circuit-breaker to be selectively provided either with a hand switch, or with an automatic switch (oil switch), or with 'a switchable fuse, without it being necessary for said bay, which forms an integral part of the swltchgear (reference being had, for instance, to metalclad switchgear) to be modiiled, .or for the bay (or for that portion of the switchgear to which the bay is. allocated) to be rendered dead. -v

The invention, therefore, provides a universal circuit-breaker. Since the electric neid distribution in a circuit-breaker in accordance with the invention, can be very favourable, it is not necessary for a circuit-breaker for very high tension, say 150 K. V., to differ, or to materially dliler from a circuit-breaker for less high tension, say 10 K. V.

- What I claim is:

1. A circuit breaker for high voltage currents, comprising a fixed metal tank comprising two vertical tubular casings communicating with one another at their top endsand adapted to be filled with an insulating iiuid such asmineral oil, insulators mounted adjacent the bottoms of said casings in the wall thereof, fixed leading-in conductors passed through said insulators and extending with one of their ends into said casings,

a contact make and break element'comprising 4iixed switch contacts and an axially movable plugging contact cooperating therewith and arvided at said ends of the leading-in conductors,

the contact means connected to the iixed switch contacts and those provided lat the leading-in conductors releasably engaging one another so as to permit the contact make and break element tacts of said element spaced apart,

to be entirely withdrawn from' and inserted into said tank, while the leading-in conductors are alive and the tank with the leading-in conductors remains in place.

2. A circuit breaker for high voltage currents, comprising a xed -metal tank adapted to be illled with an insulating iluid such as mineral oil, insulators positioned in the wall of said tank, fixed leading-in conductors passed through said insulators and extending with one of their ends into said tank, a contact make and break element comprisingflxed switch contacts and an axially movable plugging contact cooperating therewith, an insulating bushing in which the contact make and break element is coaxially arranged and which keeps the xed switch concontact means connected both electrically conductively and mechanically rigidly to said xed switch contacts, contact means provided at said ends of the `leading-in conductors, the contact means connected to the iixed switch contacts and those provided at the leading-in conductors releasably engaging one another so as to permit the contact make and break element to be entirely withdrawn from and inserted into the tank, while the leading-in conductors are alive and the tank with the leading-in conductors remains in. place.

3. A circuit breaker for high voltage currents, comprising a fixed metal tank comprising two vertical tubular casings communicating with one another at their top ends and adapted to be filled with an insulating iluid such as mineral oil, insulators mounted adjacent the bottoms of said casings in the wall thereof, iixed leading-in conductors passed through said insulators and extending with one of their ends into said casings, a contact make and break element comprising xed switch contacts and an axially movable plugging contact cooperating therewith and arranged in one of the tubular casings with the axis of the movable plugging contact in the axis of that casing,'resillent contact sleeves of which the one is directly connected to one of the fixed switch contacts and is arranged in the casing with the contact make and break element and the other'is arranged in the other casing and is connected'to the other nxed switch contact through a bridging conductor, plugs provided at said ends of the leading-in conductors, the redllent contact sleeves connected to the iixed switch contacts and the plugs provided' at the leading-in conductors releasablyengagingoneanothersoastopermit the contact make and break element `to beentirely withdrawn from and inserted into the tank, while the leading-in conductors are alive and the tank with the leading-in conductors remains in Pll.

HINDRIKA. H'IDDEA NIJLAND.

Images