MXPA99008228A - Two pole contactor - Google Patents

Abstract

A two pole contactor, particularly for a domestic electricity meter, comprising a solenoid with a plunger actuator (24) and a movable contact (16) for each pole mounted on a pivotal blade (14) in a symmetrical opposed configuration. The plunger is connected to the blades by a leaf spring (38) whose ends engage sliders (40) connected to the blades to impart a similar and even movement to each blade.

Description

TWO-POLE AUTOMATIC SWITCH FIELD OF THE INVENTION The present invention relates to a two-pole circuit breaker, particularly for use in domestic electricity meters in which it is desired to have a total isolation between the utility side or the measurement of the electricity supply and the domestic circuits.

BACKGROUND OF THE INVENTION The distribution system in North America is such that the domestic premises are fed with a 2-phase utility supply (180 ° phase ratio), the central derivation of the local transformer that gives an artificial Neutral for cards from normal to low current at 115V, while the transverse voltage phases are 230 V for power loads such as air conditioners, drive motors and heaters. The primary local transformer is usually fed from a supply REF .: 31263 of 25 KV fused high, so that the switch contacts of the contactor or circuit breaker must safely resist any reasonable short circuit fault on the load side of the meter. The known contactor designs exist to perform such switching functions in association with domestic electricity meters used in North America. In US 4388535 the power connections are provided with sets of fixed pairs of contacts, and related sets of short circuit bars connected, with springs or springs, are placed in the vicinity of the fixed contact assemblies, such that they are by actuating the two sets of switches that make contact, connecting the power or utility side to the domestic load side. The actuation is achieved by a piston of motion within an energizing solenoid coil, and a set of pivoted angled cam levers that operate by pushing to open the spring shorting bars or to retract by closing them, the forces of the springs they provide the necessary contact closure. An icro-switch is used to interrupt the coil of the solenoid operated during the OPEN and CLOSED actuation functions, which ensure that the energization is only momentary, thus preventing the coil from overheating and possible burning. In US Pat. No. 4,430,579, the construction is similar to US Pat. No. 4,338,535, using sets of short-circuit switches connected to springs to create the function of the 2-pole contact. But the adopted method of operation is different in that the solenoid is double actuated, the piston being naturally attracted centrally in a coil or energized power coil when it is energized, this is the largest point of flow concentration. In this central attraction, the piston is dynamically driven past its center to mechanically secure at each end of its stroke. The coil energy is typically 2,000 W for a reliable double action mechanical assurance function. This double action of the solenoid is used to transfer the switching function via push rods aided by the guided roller conveniently, either to CLOSED or OPEN the two spring switch assemblies, the closing force of the contact is provided by the springs of compression that go beyond each short circuit bar. To ensure that the contacts do not separate under short-circuit fault conditions, a relatively high force must be applied for each compression spring. - The piston of the solenoid is profiled in such a way that it performs both the functions of mechanical securing and translation simultaneously. A variant of the profiled piston uses a hardened steel plate, similarly profiled, suitably secured to the piston, to perform the same mechanical translation and securing functions, respectively. A microswitch is used again to interrupt the solenoid coil drive to prevent the coil from overheating.

DESCRIPTION OF THE INVENTION It is an object of the present invention to provide an improved two-pole automatic switch.

Brief Description of the Invention According to one aspect of the present invention there is provided a two-pole automatic switch comprising a solenoid having an automatic piston switch, a fixed contact and a movable contact for each pole, the movable contacts are each mounted symmetrically - in a pivotal blade or blade, in which the piston is connected to the center of a leaf spring or spring, whereby in the use of the ends thereof they impart a similar and uniform movement to each leaf or blade. According to another aspect of the present invention there is provided an automatic switch having at least one pair of single contact poles and a solenoid operated piston for driving the contacts, in which the piston part external to the solenoid is made of material Non-magnetic to reduce the influence of magnetic interference fields during conditions of excess current or short-circuit failure. According to a further aspect of the present invention there is provided a circuit breaker comprising a solenoid with a piston actuator mounted within a metal frame and deflected by a spring to the open condition of the circuit breaker, the piston is brought into contact with a stop or retainer in the frame in the closed condition, in which the state of the circuit breaker is determined by passing a voltage between the frame and the spring, so that a circuit is made when the piston comes into contact with the retainer in the closed condition. - Other features of the invention are defined in the appended claims.

Brief Description of the Drawings A circuit breaker in accordance with the invention will now be described, by way of the single example, with reference to the accompanying drawings in which: Figure 1 is a plan view of the circuit breaker with the top removed to show the similarities of the blades or blades. Figures 2A to 2D are views of a U-frame for the protected solenoid, showing respectively a top view, a plan view taken on the partial section line II-II of Figure 2A, a side view , and a bottom view of the frame; Figures 3A and 3B are views of a side and bottom respectively of a busbar assembly incorporating a movement blade or blade; and Figure 4 is a plan view showing a status switch in the closed position.

Detailed description Referring first to Figure 1, the circuit breaker shown is designed to fit within a domestic electricity metering cover, or in a measurement base that is molded at the interface of an enclosure, to isolate the utility power supply to domestic charges inside the house. It can also be integrated into a pre-correction or pre-reading of the proposed automatic meter (for its acronym in English AMR) and communication system, with the opinion of remote disconnection and reconnection of the consumer's supply. The automatic switch or contactor comprises a strong molded cover 8 made of an electrically non-conductive material and which forms a base on which two separated-mirror or symmetrical and balanced switching systems are mounted. To avoid unnecessary repetition of references in the drawings, only the parts on the left side of the switch will generally be referred to, it is understood that the parts on the right side are essentially similar except where specifically set. The power is fed to the circuit breaker from an internal busbar 10 which is connected by a thin spring portion 12 to a bifurcated blade or blade 14 having a pair of internal contacts 16 formed at the ends (see also Figures 3A and 3B). The power is supplied from the automatic switch or contactor of an external busbar 18 which has fixed double contacts 20 to be joined with the internal contacts 16. A solenoid actuator or actuator 24 is centrally mounted between the ends of the external busbars 18., the actuator comprises a ferrous piston 26 slidable within a solenoid drive coil 22. A bobbin 28 connected to a yoke or yoke 32 loosely engages within an opening 30 in the piston 26, to which it is connected by a bolt or pivot pin 29. At each end of the yoke 32 the surface or bottom side engages a compression spring 34, while a pair of projections 36 on the top face engages a pair of leaf springs or shaped sheet 38 , maintained at its center by a bolt 39A of a support 39 made of aluminum cover. The end of each spring 38 is engaged in a slot of a molded slidable elevator 40 (only one is shown) made of an electrically non-conductive material and of which the upper end engages the upper and lower sides of the moving blade 14. It should be noted in the present that the upper spring 38 and the upper elevators 40 are not shown in Figure 1, and that the arrangement of the leaves 12 is not only reflected, but is symmetrical and balanced around the axis of the actuator of solenoid 24, therefore have a driving force and deflection consistent via the two pairs of lifts 40 to each set of contacts in turn. The movement blade 14 is thin at one end to be flexibly attached or bonded and suitably shaped to the busbar 10 by welding, abrasion or ultrasonic welding. During the manufacture of this assembly it is important not to generate excess heat, which could seriously distort the shape of, or affect the quality of the spring of the movement blade. Each assembly is narrowly located and contained in grooves and barriers within the molded cover 8. Suitable barriers within the cover provide the required safety insulation between two individual switches which are at main supply voltages, and the drive coil 22 which is in the lower voltage.

The feed busbar 10 and the motion pad 14 are formed in such a way that they are joined together by a certain distance, with a small gap defined between, along their length. A large gap exists in the flexible connection of the portion of the spring 12 where the blade is relatively weak, to prevent damage when loaded under the failure conditions. This alabe arrangement is the basis of the so-called "blow-melt" arrangement (as described and claimed in UK Patent Application Serial No. 2295726) [ref. 480.00 / B] which is designed to provide increased contact force and therefore superior switching operation, especially under short or excessive current fault conditions Under such over current / short circuit fault conditions the current in the powered bus 10 is in the opposite direction so that it flows in the respective adjacent movement blade 14, so that electrodynamic forces are generated between them, testing them to force them away. The force is approximately proportional to the square of the current. Since the power bus 10 is comparatively rigid, these forces act directly on the motion bank, thus increasing the forces between the contacts 16, 20 during and above the optimum overtravel force which is adjusted when the Solenoid adjustment. Opposed to this increase in the force of blowing, and managing to open the contacts, is the so-called contact repulsion force, which is related to the geometry of the current flow through the contacts by themselves. The magnitude of this repulsive force induced by the field is also approximately proportional to the square of the current, and is a function of the ratio of the contact diameter to the actual contact diameter. In general, the most "contact" surfaces or "conditioned" are the lowest repulsion forces between them. The effect of these two opposing forces is a net increase in nominal contact force with increased current, thus providing more efficient and widely improved switching. Referring to Figures 3A and 3B, the pair of movement vanes 14 are shown in a condition in which the bifurcated contacts 16 are open. Adjacent to its contact end, the movement blade 14 is formed with a slightly U-shaped portion 15 such that it engages freely with the sliding lifter 40, one half below and the other half above, for the free action of the blade. . The lower end of the lifter 40 engages with a lower end of the two leaf springs 38 within the housing 39 (only a lower part is shown). Both the sliding elevator assemblies are contained by and operate continuously in notches (not shown) within the base and casing covers of the contactor. When the leaf spring support 39 is bolted freely to the actuator piston of the solenoid 26, and joins symmetrically between the two motion blade / elevator systems, this ensures that the actuation forces translated from the solenoid piston to the blades via the two leaf springs 38 are distributed at both sites, thus providing distributed, similar contact forces and reliable switching. Moreover, when each of the leaf springs 38 is trapped by the central pin 39A, it provides three fixing points within the housing 39, a limb on each side is prestressed to exert a pickup force slightly greater than the other, the result is that during the performance, one half of the contact of the blade is advanced slightly with respect to the other, creating a premature closure with its fixed contact of union, followed quickly with the closing of its counterpart. The claim is designed in such a way that at the end of the race or overtravel, the four contacts 16, 20 receive approximately the same consistent nominal contact force. Also, by virtue of the electrodynamic blowing forces, a considerably lower nominal contact force is required for operation at normal current levels, in this case 200 A rms. Typically, each contact force is in the region of 300 to 400 g (3 to 4 Newtons). This is the basis of a pair of "sacrificial" contact in each set: a contact that takes the shock of the premature closing and recent opening, with the other contact carrying the charge current. In practice, however, both contacts must distribute the load-current equally. The advantages of bifurcated contacts with a pair of sacrificial contact are as follows: a) Since the total charge current is equally distributed between the bifurcated contact assemblies, it can be shown that the total heating effect is roughly divided between two. b) Divide the charge current through each pair of "distribution" contacts by two, rather than dividing the resultant contact repulsion force by two, which is achieved by opening the contacts. c) The combined effect of a) and b) above allows a lower leaf spring force to be used. This also makes the arrangement less welded by a critical torch, while still providing an improved reliable switching duration to the contactor or circuit breaker. The operation of the solenoid 24 is ensured by rare earth magnets 37 and requires only a short CD pulse for its operation and release functions, the clamping force assured being considerably greater than the total contact force exerted via the double leaf springs 38 This surplus support ensures that the contactor function is not susceptible to shock and vibration, or excessive current forces. The actuator is thus secured by magnets, and requires only a short momentary DC pulse to perform the operation and release functions, no quiescent energy is required. This virtually eradicates any self-heating, as is the case in a solenoid assurance without magnets. Typically, the drive power of the coil is only of the order of 20 to 30 W (compared to 2000 W for the known contactors, cited above), with actuation or drive periods of typically 20 ms. As shown, the actuator or actuator of the solenoid 24 is damaged by a single coil, requiring for example a positive DC pulse to operate (CLOSED) and a negative DC pulse to release (OPEN) the contactor switches, and require a simple inverted bridge type of drive circuit. Alternatively, however, the solenoid can be damaged with two coils with a common center shunt, which requires DC pulses of the same polarity (ie negative drive with respect to a common positive center shunt, of separate conduction transistors) , to achieve the functions of the operation contactor (CLOSE) and release (OPEN). Alternatively in a preferred single coil option, the drive is performed directly from the AC supply, for example via optoisolated triac or electronic commutator, where it is only necessary for a positive half cycle to operate (CLOSE) and for a negative half cycle for release (OPEN) the contact function. In this case, it is advantageous for the triac drive to be fired from the so-called zero crosslinking of the supply, by ensuring that the contacts open and close in a rapidly declining load current (or preferably in the next zero crosslinking). ), resulting in minimal electric arc formation, improved commutation and extended contact duration.

To assist the release function, the two pressure-release springs 34 are located between the leaf spring housing 39 and the cover of the contactor 8. The axial position of the solenoid is adjustable so that a minimum contact force is achieved, which is then fixed with a pair of screws 54 (see Figure 4) in recesses in the cover, and glued with glue to add retention during the life of the contact. A molded top cover provides suitable capsules, which closely contain and integrate the complete assembly within the cover or liner. Referring now to Figures 2A and 2D, a secondary U-frame 42 is shown to cover the solenoid. The frame comprises a base 44, a pair of sides 48, from one of these extends a fixing ring or projection 48, an upper side 50 and a lower end 52 having a small central housing 54. The rings or projections 48 are secured to the molded base 8 by fasteners, as shown in Figure 1. The frame 42 thus consists of a four-sided box structure, which is also enclosed at the lower end, and by the aluminum support 39 beyond its upper end, thereby excluding Large magnetic fields produced by sheet assemblies during fault conditions due to short circuit or excess.

Auxiliary state switch for the function of the actuator / contactor Some final applications require an auxiliary low-voltage switch, to signal the electronic elements of activation, or to indicate remotely, which part of a prepaid system or Automatic Measurement Reading (AMR), the status of the contactor (or in much smaller, the state of the solenoid actuator). A simple version of a status switch is shown in Figure 4. While the contacts 16 and 20 are open, the movement piston 26 is insulated in a plastic coil of a metal end stop 56 and the solenoid frame 42 (at the lower end) by the running distance, typically 2-3 mm. However, the piston is in continuity with the mounting of the aluminum leaf spring bracket and both springs pushed out 34. As already mentioned, the functionality of the present circuit breaker depends on the successful securing of the magneto solenoid, essentially involving a intimate, strong attraction of the metallic piston 26, the detent 54 and the frame 42, when the contacts are closed. This assurance retention force is typically several kilograms, and forms a low voltage, low voltage, ideal switching. A wire connection 58 is made of one of the fastening screws 54 for the frame 42, and a similar wire connection 60 is made of the adjacent momentum spring or spring 34 by means of an end (not shown) trapped under the spring . The wire connections 58 and 60 are fed to a flag or flag circuit to show the state of the switch. When the circuit breaker is in the closed position shown, a continuous circuit is formed as shown by dotted line 62. Therefore, an electrical circuit is formed as follows: from the wire 60 through the spring or spring, as length of a lever of the aluminum yoke 32, through the pivot pin 29 and the piston 26, crosses the nickel silver interface with the retainer 56, along the side of the frame 42, and out of the screw 54 to the wire 58 The wires 58 and 60 are fed to a flag circuit to show the status of the contactor, for example, by an indicator light (not shown).

Immunity to large magnetic fields generated Some USA and IEC specifications require normal operation of the contactor following a 6 cycle failure of 6,000 A rms, or a 1/2 cycle failure of 10,000 A rms. During such short circuit / excessive faults, many large magnetic fields are generated by the busbars 10, the movement blades 14 and electrical load channel connections. The effect of these large magnetic fields is to interfere with or influence the established housing conditions of the magneto-secured solenoid which in some cases can actually force the solenoid until it drips, opening the contacts of the circuit breaker or contactor, with catastrophic consequences. Magnetic interference fields can be part of a solenoid for securing by magnets in three ways: - 1) inducing forces via the surface or face of the end of the piston in the leaf spring carrier 39 (which is in close proximity to one of the movement blades), thus directly affecting the net clamping of the solenoid to the blasting point, or 2) inducing forces directly on the piston 26 and / or end retaining parts within of the coil area, which again affect the net clamping of the solenoid, or 3) partially demagnetizing the magnetos of the Ferrita of conventional existence 37 momentarily during the performance. To reduce the effect of large magnetic interference fields in fault conditions, the present drawing provides the following characteristics: 1) The ferrous piston 26 is short-circuited so that only the magnetically active portion is contained within the solenoid secured by magnets, the portion external actuation is attached to the support of the aluminum sheet spring 39 which is not magnetic, for example, insert molded plastic or an extension of the housing or support 39. This considerably reduces the interference influence of the fault condition magnetic fields big. 2) The rest of the solenoid is protected and enclosed by the secondary U-frame 42, in such a way that the additional reduction is achieved in the interference influence of the large magnetic fields. 3) The use of rare earth magnets 37 which not only provides considerably high housing or holding forces, but also makes them inherently difficult to magnetize because of their larger magnitude BHmax product, which is typically 30 to 35 Mega.Gauss .Oersteds (MGO) compared with 3 to 6 MGO for the best grades of Ferrite material that are commonly used. The combination of these three improvements is believed to virtually eradicate the problem of magnetic field influence, providing reliable, immune, solenoid operation under the most arduous short circuit / overload fault conditions.

It is noted that in relation to this date, the best method known to the applicant to carry out the aforementioned invention, is that which refers to the manufacture of the objects to which it refers. Having described the invention as above, the content of the following is claimed as property

Claims (17)

1. A two-pole automatic switch characterized in that it comprises a solenoid having a piston actuator, a fixed contact and a movable contact for each pole, the movable contacts are each mounted symmetrically in a pivoting vane, in which the piston is connected to the piston. center of a leaf spring, whereby in the use of the ends of the same imparts a similar and uniform movement to each blade.

2. An automatic switch according to claim 1, characterized in that the blades are connected to an internal busbar by a spring or flexible spring portion, the blades and the busbar are disposed in a substantially parallel relationship so that in the use of Electromagnetic forces stimulates the contacts in the closest contact.

3. An automatic switch according to claim 2, characterized in that each blade divides or bifurcates to provide two mobile contacts for each pole.

4. An automatic switch according to any of claims 1 to 3, characterized in that it also comprises a support formed as a molding in two halves divisions, in which the parts therein can be easily assembled in one half.

5. An automatic switch according to claim 4, characterized in that each end of the leaf spring engages a sliding element connected to the respective blade and which is slidable in a notch of the respective half of the housing.

6. An automatic switch according to claim 5, characterized in that there are two sliding elements for each pole, one is placed above and the other under the respective blade.

7. A circuit breaker according to any of claims 1 to 6, characterized in that the solenoid actuator is assembled adjustably by fixing screws for the optimum positioning of the piston.

8. An automatic switch according to any of claims 1 to 4, characterized in that each leaf spring end engages a movable element made of an electrically non-conductive material and connects to the respective blade.

9. An automatic switch having at least a pair of simple contact poles and a solenoid-operated piston to actuate or actuate the contacts, in which the part of the piston external to the solenoid is made of non-magnetic material to 'reduce the effect of the magnetic fields during conditions of excess current or short circuit fault conditions.

10. An automatic switch according to claim 9, characterized in that the non-magnetic material is a metal.

11. An automatic switch according to claim 9 or claim 10, characterized in that the solenoid is contained within a four-sided metal box frame to further reduce the effect of the magnetic interference fields.

12. An automatic switch in accordance with any of. claims 9 to 11, characterized in that the solenoid is of a type of closure or securing by magnets and wherein the magnets are made of a rare earth material to reduce any demagnetizing effect during a fault condition.

13. An automatic switch comprising a solenoid with a piston actuator mounted within a metal frame and deflected by a spring to the open condition of the circuit breaker or contactor, the piston contacts a retainer in the frame in the closed condition, so which state of the circuit breaker can be determined by passing a voltage between the frame and the spring, so that a circuit is made when the piston comes into contact with the detent in the closed condition.

14. An automatic switch according to claim 13, characterized in that it has two poles each with a blade carrying a moving contact and acting on the piston.

15. An automatic switch according to claim 14, characterized in that the piston acts or drives the respective vanes via the ends of a leaf spring.

16. A circuit breaker according to claim 15, characterized in that the piston is in contact with a yoke which is coupled to the leaf spring, this is a bypass spring under each yoke to assist the solenoid when operated to open the contacts.

17. A circuit breaker substantially as described with reference to and as illustrated in Figures 1 to 4 of the accompanying drawings.