EP0008583A1 - Indicator for blown circuit breaker - Google Patents

Abstract

A circuit breaker trip indicator is used with a conventional type circuit breaker (9). The circuit breaker trip indicator comprises a circuit comprising a light emitting diode (50), in series with a second switch and a connection (55) to the earth which derives the current from the load (49) which is supposed to have caused the overload conditions of the circuit breaker (9), the light emitting diode being arranged at the front (12) of the case (10) of the circuit breaker (9) in order to allow a visible indication of tripping of the circuit breaker. In one embodiment, the light emitting diode (50) is activated by a second switch (57) when the circuit has been tripped, and in another embodiment, which provides for the use of a plurality of circuit breakers, the light is only deactivated by a second switch (57) on the circuit breakers that have tripped.

Description

DESCRIPTION

TITLE: I. INDICATOR FOR BLOWN CIRCUIT BREAKER II. TECHNICAL FIELD The present invention relates to circuit breakers and more specifically to means of indicating that a circuit breaker has blown. III. BACKGROUND ART As commonly used, conventional circuit breakers are placed in banks of several side by side units, with each circuit breaker having an operating handle extending outward from the front of the casing of the circuit breaker. Normally, the handle has two extreme positions, an "On" position in which the circuit breaker completes the circuit, and another extreme position or "Off" position, in which the circuit is interrupted or opened. When this load circuit is overloaded, it will "blow", or more specifically, the load circuit is interrupted by a circuit overload response member. -When this circuit overload response member interrupts or opens the circuit, simultaneously the operating handle moves to an intermediate position between the two above described extreme positions. With the standard circuit breakers presently on the market, it is difficult to determine whether or not a breaker is in this intermediate position or "blown" position, and not in one of the two extreme positions. This problem is made substantially worse when a plurality of circuit breakers are positioned in side-by-side relationship, as they commonly are in conventional practice. When one of the circuit breakers has its operating handle in the "blown" position, it is particularly hard to _/-^gU t^'A^ determine that this condition exists, especially where the circuit breakers are located in cellars or other dark locations. This makes it difficult for the cause of the overload to be found and corrected by resetting the breaker. As is common practice with the prior art circuit breakers, resetting consists of moving the operating handle to the "off" position, and then subsequently moving the same to the "on" position. Conventional type circuit breakers found in the prior art are illustrated in U.S. Patents Nos. 2,618,716; 2,663,773; 2,781,433; 2,924,683; 2,989,604; 3,636,482; and 3,930,211. This application is a continuation application of U. S. application serial number 871,487, filed January 23, 1978, which is a continuation-in-part of U.S. application serial number 847,007, filed October 31, 1977 (now abandoned) which in turn was a continuation- in-part of U.S. application serial number 729,664, filed October 5, 1976 which is now U. S. Patent number 4,056,816 issued on November 1, 1977.

IV. DISCLOSURE OF THE INVENTION

The present invention is directed to a blown circuit indicator to be used in combination with a conventional circuit breaker. The conventional circuit breaker load circuit normally comprises first switch means for opening or closing the load circuit, and a tripping means for triggering the first switch means to interrupt the load circuit in response to an overload condition of the load circuit. The problem found with conventional circuit breakers, including the device described and claimed by this inventor in U. S. patent number 4,056,816, is that when a light indicator is used there is a small current flowing through the light indicator circuit, which is in parallel with the load circuit, and through the load. refers- to the circuitry outside the circuit breaker that is being fed. "Load circuit" refers to the circuit inside the circuit breaker comprising a first switch means and a tripping means) . This small current that continues to flow through the load may be hazardous since it forfeits the original purpose of the circuit breaker, namely, to cut off the current to the load in response to an overload condi- tion. Consequently, there are a number of safety agencies that would not approve the use of circuit breakers with overload indicators of this type. The improvement of the present invention comprises a blown breaker indicator circuit having a second switch means and a connection to a third neutral contact thereby eliminating the above mentioned flow of current through the load. It is a primary object of the present invention to provide a light indicator for a conventional circuit breaker that can be used safely to facilitate the locating of a circuit breaker that has blown. A further object of the present invention is^' to provide a light indicator for a conventional circuit breaker, which will activate a light emitting diode in the front panel of the breaker casing, so that there will be visible indication that a particular circuit breaker has blown. A related object of the present invention is to provide another embodiment of the present invention in which a light emitting diode is deactivated so as to visually indicate that a particular curcuit breaker has blown. Yet another object of the present invention is to provide an indicating light in the front' panel of the circuit breaker which is either activated or deactivated and stays in such a condition until the blown breaker has been reset, presumably after the cause of the overload on the circuit has been corrected. Yet another object of the present invention is to provide a blown circuit indicator using light means located in a readily visible location remote from the location of the overload responsive component so that if any heat caused by the overload responsive component will be sufficiently distant from the light means so as not to cause damage to the same. Yet another object is to provide a light indicator means for a circuit breaker whereby one can quickly determine which circuit breaker out of a plurality of side-by-side circuit breakers have been blown.

V. BRIEF DESCRIPTION OF DRAWINGS

With the above and other related objects in view, this invention consists in the details of construction and combination of parts as will be more fully understood from the following description, when read in conjunction with the accompanying drawings, in which: FIG. 1 is an elevation view of the second embodiment of the present invention having the conventional bimetallic circuit breaker to which the blown breaker indicator circuit of this invention has been added, with the circuit breaker being "on", the face or cover of the casing being omitted. FIG. 2 is an elevation view of the embodiment shown in FIG. 1, with the circuit breaker being "blown". FIG. 3 is an elevation view of the first embodiment of the present invention having the conventional bimetallic circuit breaker to which the blown breaker indicator circuit of this invention has been added, the circuit breaker being "on". FIG. 4 is an elevation view of the embodiment of FIG. 3 with the circuit breaker being "blown". FIG. 5 is a schematic diagram of the first embodiment of the present invention shown in FIG. 4. FIG. 6 is a schematic diagram of the second embodiment of the present invention of FIG. 2. FIG. 7 is a diagramical view of the circuit breaker of the present invention interconnected with the load of a power system. VI. BEST MODE OF CARRYING OUT THE INVENTION A conventional blown circuit breaker, generally indicated as 9, is shown having a housing or case 10 suitable insulating material and in which the side cover or face is omitted from the illustration to enable the interior, parts to be illustrated. The case and cover are typically of molded insulating plastic. The various elements of a conventional circuit breaker mechanism, and also the elements of this invention, are mounted with the case 10. The case 10 has a front panel 12 through which an operating handle 13 extends. In FIG. 1 the handle 13 is shown in load circuit "ON" position 14 and in dotted outline, the handle 13 is shown in "OFF" position 15. In FIG. 2 the handle 13 is shown in its "blown" position 17. The circuit breaker 9 has first and second line terminals 18 and 34 which electrically connect the breaker 9 to the load to be protected. A load circuit 8 including first switch means 25 is electrically connected at one end to line terminal 18 and at the other end to line terminal 34. As commonly provided in conventional circuit breakers, the first line terminal 18 provides ideally a fixed contact 16 mounted in the casing 10 to engage a main bus bar 19 when the circuit breaker is inserted into a distribution panel (not shown) . As illustrated in FIG. l,a lever 22 having a movable contact 20 is shown in its circuit completing position 21 and in dotted outline, its open posi- tion 23. On the opposite end of lever 22 relative to movable contact 20 there is integrally formed the handle 13. The first switch means 25 is defined to include the first line terminal 18 and lever 22 which forms a circuit interrupting switch. The specific structural design of first switch means 25 is of conventional design and can take many different forms. The conventional circuit breaker 9 is of the type which is normally provided with overload tripping means 31 having a trip arm 24 pivoted on a boss 26 secured to the case 10, whereby the arm 24 is pivoted between a set position 27 shown in FIG. 1 and a tripped position 29 shown in FIG. 2. An overcenter tension spring 28 has one end connected to the lever 22 and the other end connected to the trip arm 24. The handle 13, lever 22 and spring 28 form an over- center arrangement, or toggle, and urges the movable contact 20 towards the fixed contact 16 when the spring 28 is on one side of the pivot point 30 shown in FIG. 1 and urges the movable contact 20 to the open position when the spring 26 is on the other side at the pivot point 30, as shown in FIG. 2. The current responsive member of the overload tripping means 31 is a thermally responsive or bimetallic latching member 38 which retains said tripping means in its set position 27. The specific structural detail of the overload tripping means 31 is known to the art, and can take numerous forms when combined with the present invention. Ideally, a load terminal connecting screw 32 mounted in a bus

OMPI _. niIrPOu t 1 bar 35 is provided for connecting the circuit breaker 9 to the

2 load (not shown) . The load terminal connecting screw 32 defines

3 the second line terminal 34, and is preferably riveted or screwed

4 to case 10 at 36. The thermally responsive latching member 38

5 is a generally hook shaped thermostat element of at least two layers

6 of metal having different coefficients of thermal expansion so that

7 the element bends as its temperature increases. Furthermore, the

8 end of the bimetallic member 38 is connected through second line

9 terminal 34. The structure recited in this paragraph is of conven-

10 tional design. .

11 The circuit breaker operates in the customary manner for

12 opening and closing the contacts, and also for tripping under the

13 action of an overload. As thus far described, this circuit breaker

14 is conventional and operates in the customary manner. This conven-

15. tional construction is the same as disclosed in U. S. Patent No.

16 3,930,211 and also in many other prior patents in this art. This

17 particular conventional circuit breaker 9 is incorporated in the

18 preferred embodiment of the present invention only for the purposes

19 of illustration. Furthermore, the present invention could be practiced

20 with other types of conventional circuit breakers. For instance, the

21 present invention could be used in combination with a conventional

22 magnetic circuit breaker as described in the parent U. S. application

23 and U. S. -patent for this application, serial No. 847,007, filed

24 October 31, 1977 and Patent No. 4,056,816. In such a breaker the

25 tripping means 31 would comprise primarily a magnetic coil with its

26 associated armature.

27 In the first embodiment of this invention, light means 50,

28 preferably in the form of a light emitting diode, is activated when

the circuit breaker 9 has blown. In another embodiment of the present invention, the light means 50 will be deactivated when the circuit breaker is blown. The first embodiment is illustrated in FIGS. 3 and 4 and the second embodiment is illustrated in FIGS. 1 and 2. In both embodiments, the light means 50 is positioned at the front of the casing 10 on front panel 12 so as to provide a visual indication of when the circuit has been blown. In both embodiments of the present invention as shown in FIGS. 3 and 4, the blown breaker indicator circuit 33 includes in series a second switch means 57, resistor means 44 and light means 50. The blown breaker indicator circuit 33 »is electrically interconnected at one end to the third line terminal 37 which is a neutral line. At the other end, the blown breaker indicator circuit 33 is electrically interconnected to the first line terminal 18. The first line terminal 18 is electrically connected to the main bus bar 19. The third line terminal 37 is electrically connected to the neutral. As with all embodiments of the present invention, the first and second line terminal 18 and 34 connect with the load 49. The order of the second switch means 57, resistor means 44 and light means 50 in their series relationship can be changed as long as they are in series. Both the embodiment of FIG. 1 and the embodiment of FIG. 3 can be utilized in conventional DC or AC power systems, whether it is a single phase, two phase or three phase system. Likewise, it is immaterial whether the power system is having drawn therefrom 110 volts or 220 volts. More specifically, the circuit breaker 9 is electrically inserted in series with the hot phase line 51 by first and second line terminals 18 and 34, as shown in FIG. 7. The blown breaker indicator circuit 33 is electrically coupled to a neutral or ground 55 of the power distribution system so as not to be in series with load 49. In a conventional 220 volt power distribution system, there would be two breakers 9 inserted in the two hot phase lines 51 with the blown breaker indicator circuit 33 of each of the breakers 9 electrically connected to normally a single neutral line 55. Likewise, in a three phase power source system there would normally be three circuit breakers 9 inserted in each of the three hot phase lines 51 with three blown breaker indicators circuit 33 interconnected with a single neutral ground 55. Therefore, the above illustrated examples of conventional power systems is provided merely to emphasize the fact that the present breaker 9 with the associated invention can be incorporated into any conventional power system. In each case, the circuit 33 would be interconnected with the phase line 51 at a point intermediate to the power supply 53 and the first switch means 25. In both embodiments of the present invention as shown in FIG. 1 and FIG. 3, there is provided the thermal responsive member 38, prefer- ably in the form of a bimetal strip which is mechanically linked to second switch means 57. In a conventional manner when the current exceeds a predetermined or dangerous rate, the thermal responsive member 38 will activate second switch means 57 substantially at the same time that the first switch means 25 is opened. For purposes of illustration, the thermal responsive member 38 is shown in its non- activated position 45 and its activated position 47, as shown in FIGS. 1 and 2. When the excessive current in load circuit 8 exceeds the predetermined danger value, the excessive heat thereby generated triggers the thermal responsive member 38 from its non-activated position 45 to its activated position 47. The movement of the thermal responsive element 38 creates a corresponding movement with second switch means 57 so as to open or close the blown breaker indicator circuit 33, depending upon the embodiment. In the first embodiment shown in FIG. 3, the light means 50 will be initially "off" with the first switch means 25 closed, thereby defining a completed load circuit 8. Subsequently, the light means 50 will be activated or "on" when the breaker 9 has been tripped, or more specifically, when first switch means 25 is triggered to its circuit interrupting relationship with load circuit 8 as shown in FIG. 4. More specifically, as the thermal responsive member 38 bends into its activated position 47, second switch means 57 is pulled into circuit completing relationship with the blown breaker indicator circuit 33. Ideally, as shown in the preferred embodiment second switch means 57 comprises a curvilinear contact wire 58 disposed in spaced apart relationship to an elbow shaped prong 59. This elbow shaped prong 59 is an extension of 24. Upon the trip arm 24 being released by the thermal responsive member 38, the curvilinear wire 58 electrically engages the elbow shaped wire prong 60, as shown in FIG. 4. In the second embodiment of the present invention depicted in FIG. 1, the light means 50 will be initially "on" or activated with first switch means 25 disposed in circuit completing relationship to the load circuit 8. Subsequently, light means 50 will be "off" or deactivated when first switch means 25 is disposed in circuit interrupting relationship wLth the load circuit 8 as shown in FIG. 2. In other words, the light means 50 will be deactivated or ^■off" when an overload to the load circuit 8 occurs. This particular breaker design has practical utilization when a plurality of breakers 9 are incorporated into a single distribution panel. Therefore, there would be a row of light means 50 displayed from a plurality of circuit breaker 9, so that the deactivation of at least one of the light means 50 would become apparent to an observer. Generally, this embodiment differs structurally from the other embodiment in^' that as thermal responsive member 38 bends to its activated position 47, the second switch means 57 is pulled forward so as to be disposed in circuit interrupting relationship to the blown breaker indicator circuit 33. Ideally second switch means 57 has its curvilinear wire 58 disposed in electrical engagement with its elbow shaped wire prong 60 when the trip arm is not released, as shown inJ-IG. 1. Upon the trip arm 24 being released by the thermal responsive member 38, the curvilinear wire 58 is in spaced-apart relationship to the wire prong 60 as shown in FIG. 2. The simplified schematic of the circuitry involved in both embodiments of the present invention is presented in FIG. 7. From the simplified schematic, it can be seen that unlike some of the prior art devices, the blown breaker indicator circuit 33 is not in parallel with first switch means 25. More specifically, by electrically interconnecting the blown breaker indicator circuit to a neutral or ground, the load, identified and represented by reference number 49, is free of any current flow when the first switch means 25 is open. This meets certain industrial requirements that. there be no current flow through the load circuit 8, no matter how small, when the breaker 9 has been tripped or blown. Prior schemes to provide a light means 50 that would be activated when the circuit breaker 9 was blown led to circuit designs having a current flow through load 49. Although such current flow was small, it is unacceptable in meeting the regulatory requirements of such circuit breakers. Although the preferred embodiment is shown with a mechanical tripping means 31, the present invention can be incorporated with other conventional breakers, such as the magnetic type described in the parent application of this application, serial no. 847,007 filed October 31, 1977 and issued as U. S. Patent No. 4,056,816. Such a magnetic circuit breaker (not shown) having a magnetic coil and armature would comprise the tripping means 31 of the present invention. More specifically, when there was an overload, in a well known matter the armature would pull the lever 22 to move its contact 20 away from the terminal contact 16. To summarize the operation of the embodiments of the present invention, the handle 13 operates first switch means 25 which includes lever 22 to make or break the load circuit 8 through contact 16 and movable contact 22 in the normal manner. At the same time, the overload of load circuit 8 causes trip arm 24 to change the state of second switch means 57, or more specifically, to either open or close second switch means 57. When second switch means 57 is opened or closed, the light means 50 is deactivated or activated respectively. In either case, the change of the light means 50 from its normal on-off state will provide a blown breaker signal indicating that the circuit breaker 9 has been blown. Although particular embodiments of the invention have been shown and described in full here, there is no intention to thereby limit the invention to the details of such embodiments. On the contrary, the intention is to cover all modifications, alternatives, embodiments, usages and equivalents^•of the subject invention as fall within the spirit and scope of the invention, specification and the appended claims . VII. INDUSTRIAL APPLICABILITY It is apparent from the previous paragraphs that an improve- ment of this type for circuit breakers is quite desirable, and in some cases, even necessary. Frequently, the circuit breakers are located in cellars or in other dark places inside the buildings where they are installed. If the electric power is cut-off, the user will have to secure independent lighting means to figure out which circuit breakers blew out. Furthermore, inherent in the mechanism of these breakers is the disadvantage of a very small travel of the switch handle when a circuit breaker is blown and this small travel is difficult to detect, especially when there are a few dozens of these devices in a bank. The introduction of a safe lighted indicator is therefore a valuable improvement in this technology.

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Claims

What is claimed is, 1. A circui^'t breaker comprising: a) a load circuit having a power receiving first terminal, first switch means for electrically opening said load circuit, tripping means for activating said first switch means to open said load circuit in response to an overload condition of said load circuit; b) a neutral third terminal electrically insulated from said circuit; c) a blown breaker indicator circuit including light means operable to provide a blown breaker signal and second switch means electrically connected in series with said light means, and said blown breaker indicator circuit having one end thereof electrically connected to said power receiving first terminal and the other end thereof being connected to said neutral third terminal; d) overload detector means for activating said tripping means and for changing the on-off state of said second switch means in response to an overload condition of said load circuit. 2. The circuit breaker of claim 1, wherein said second switch means is a normally closed switch responding to an overload condition of said load circuit. 3. The circuit breaker of claim 1, wherein said second switch means is a normally open switch responding to an overload condition of said load circuit. 4. The circuit breaker of claim 2, wherein said overload detector means comprise a thermal responsive element disposed in heat receiving relationship to said load circuit and said thermal responsive element being mechanically coupled to said second switch means through said tripping means whereby movement of said thermal responsive element in response to an overload condition opens said second switch means. 5. The circuit breaker of claim 3, wherein said overload detector means comprise a thermal responsive element disposed in heat receiving relationship to said load circuit and said thermal responsive element being mechanically coupled to said second switch means through said tripping means whereby movement of said thermal responsive element in response to an overload condition closes said second switch means. 6. The circuit breaker of claim 4, wherein said first switch means includes a lever adapted for electrical disengagement from said power receiving first terminal when triggered by said tripping means and wherein said tripping means includes a trip arm releasably latched to said thermal responsive element whereby said trip arm is released by said thermal responsive element in response to an overload and said trip arm being connected to said second switch means whereby movement of said trip arm upon being released opens said second switch means. 7. The circuit breaker of claim 5, wherein said first switch means includes a lever adapted for electrical disengagement from said power receiving first terminal when triggered by said tripping means and wherein said tripping means includes a trip arm releasably latched to said thermal responsive element whereby said trip arm is released by said thermal responsive element in response to an overload and said trip arm being connected to said second switch means whereby movement of said trip arm upon being released closes said second switch means. 8. The circuit breaker of claim 1 wherein said light means comprises a light emitting diode. y^ ^' y ,

O.V.Pi X _ _. ^"^Ϊ O~ ^' 9. The circuit breaker of Claim 1, wherein said blown breaker indicator circuit including a resistor disposed in series with said light means. 10. In the combination of a circuit breaker with a power distri- bution system having a neutral and at least one phase line electricall coupling a load with a power supply, said circuit breaker comprising a load circuit forming a portion of said phase line, tripping means for activating said first switch means to open said load circuit in response to an overload condition of said load circuit, the improve ment comprising: a) a blown breaker indicator circuit with one end thereof electric ally interconnected to the phase line of the power distribution system at a position intermediate to the power supply and the first .switch means. b) said blown breaker indicator circuit having the other end thereof electrically interconnected to the neutral. c) said blown breaker indicator circuit including light means operable to provide a blown breaker signal. d) second switch means electrically interposed in series with said light means. e) overload detector means for changing the on-off state of said second switch means in response to an overload condition of said load circuit. 11. In the combination of Claim 10, wherein said second switch means disposed in electrically interrupting relationship to said blown breaker indicator circuit in response to the overload condition of said load circuit. 12. In the combination of Claim 10, wherein said second switch means disposed in circuit completing relationship to said blown breaker indicator circuit in response to the overload condition of said load circuit. 13. In the combination of Claim 11, wherein said overload detector means comprising a thermal responsive element disposed in heat receiving relationship to said load circuit, and said thermal responsive element mechanically coupled to said second switch means whereby movement of said thermal responsive element in response to the overload condition opens said second switch means. 14. In the combination of Claim 12, wherein said overload detector means comprising a thermal responsive element disposed in heat receiving relationship to said load circuit, and wherein said thermal responsive element mechanically coupled to said second switch means whereby movement of said thermal responsive element in response to the overload condition closes said second switch means. 15. - In the combination of Claim 10, wherein said first switch means including a lever adapted for electrical disengagement from said phase line when triggered by said tripping means. 16. In the combination of Claim 10, wherein said light means comprising a light emitting diode. 17. In the combination of Claim 10, wherein said blown breaker indicator circuit including a resistor disposed in series with said light means. 18. In the combination of Claim 13, wherein said first switch means including a lever adapted for electrical disengagement from said power receiving first terminal when triggered by said tripping means, and wherein tripping means having a trip arm releasably latched by said thermal responsive element, and wherein said trip arm being released by said thermal responsive element in response to the over- load, and wherein said trip arm being attached to said second switch means whereby movement of said trip arm upon being released opens said second switch means. 19. In the combination of Claim 14, wherein said first switch means including a lever adapted for electrical disengagement from said power receiving first terminal when triggered by said tripping means, and wherein said tripping means being a trip arm releasably latched by said thermal responsive element, and wherein said trip arm being released by said thermal responsive element in response to the over- load, and wherein said trip arm being attached to said second switch means whereby movement of said trip arm upon being released closes said second switch means.