FR2954620A1 - Phase inversion device for three-phase asynchronous electric engine, has inversion assembly arranged such that two bridges take position in which two bridge parts connect respective conductive pad parts - Google Patents

Abstract

The device has an inversion assembly (210) provided with two bridges of two conductive locking collets (205), and an insulating support locked between the locking collets. A drive unit i.e. insulating bar, rotates the two bridges around an axis (AA) of the assembly. The locking collets are locked around the support. Conductive pads are placed on the support so as to be enclosed by the locking collets. A bistable actuating unit actuates the drive unit. The assembly is arranged such that the bridges take a position in which two bridge parts (215-1) connect respective conductive pad parts.

Description

TECHNICAL FIELD The invention relates to a device for reversing the direction of operation of a three-phase electric motor by reversing the connection between two phases. BACKGROUND OF THE INVENTION More generally, the invention relates to a mechanical device for inverting the connection between pairs of conductors.

STATE OF THE ART

To comply with their operating limits, the motors are associated with protection systems that make it possible, for example, to isolate the motor from the network by actuating a cut-off device in the event of detection of a short circuit or overload. . Fuses, circuit breakers, overload relays, or devices that jointly offer several types of protection have been developed to be associated with engine starts.

Moreover, in a three-phase electric motor, the direction of rotation of the motor is determined by the sequence of the phases of the power supply source. However, in some applications, the motor must be able to work in both directions, for example for a valve or a pump, a conveyor or an elevator, or another machine tool. To achieve the desired direction of starting the motor, devices have been designed to reverse the connection between two of the phases, the third remaining unchanged.

A solution is thus the integration of the inversion function in the switching or protection device: two conventional contactors / circuit breakers are associated with the aid of a mechanical lock that locks them one and the other so that the simultaneous activation of the two contactors is prohibited: see for example FR 2 373 320. This solution however requires a large number of parts, with doubling of the cut-off devices and locking system. 2713 LPu For most uses, the cut-off device which ensures the start-up and protection of the motor is maintained, simply associated downstream with a phase-reversing device (see, for example, FR 2 586 325); it is important then that the inversion device does not prevent the restart after activation of the breaking means and correction of the fault. With reference to FIG. 1, the three-phase power supply circuit 1 L1, L2, L3 of the motor 2, which is provided in the illustrated frame with an upstream cut-off device 4, comprises three connection terminals 6 on which are connected three terminals 8 of the motor 2 feeding each of the phases Ti, T2, T3. In order to allow a reversal of the direction of rotation of the motor 2, a reversing device 10 is connected to the terminals 6, 8 of each line, and comprises contacts 12, 14 with double or single break which, according to their position, make it possible to cross two of the three phases L1, L2 and Ti, T2, one of the L3-T3 phases being retained.

To prohibit the inversion of the phases under load, the inverter 10 is usually controlled by auxiliary contacts 16 of the cutoff device 4 present upstream and whose position allows or not the control 18 of the phase inversion, it is of the movement of the contacts 12, 14.

To ensure the passage of the rated current of the motor starter and withstood shocks and vibrations, the contacts 12, 14 of the reversing device 10 may be provided with silver pellets, and they are conventionally controlled by springs. Moreover, since the high currents, and in particular the short-circuit currents, tend to spread the poles connecting the supply lines L and the transmission lines T, to ensure short-circuit operation, the contacts 12 , 14 are also provided with an electromagnetic device which, under the effect of the passage of the short-circuit current causes an increase of the pressure on the phase inversion contacts: see for example FR 2 795 226. This architecture requires and a large number of parts and induces, in fact, a high cost.

SUMMARY OF THE INVENTION 2713 LPu Among other advantages, the invention aims to optimize the design of phase inverter devices and in particular to reduce the number of parts to reduce their cost. Despite this simplification in the design, the invention aims to keep the resistance of the inverter to short circuits of 10 kA or 50 kA, and in particular to tolerate short circuit current passages for 2.5 ms.

An inverter device according to the invention thus comprises at least two input terminals of two output terminals which are connected to an inversion assembly; a third input terminal and a third output terminal fixedly connected by a conductor may be present.

The inversion assembly includes conductive clamps for connecting conductive pads connected to the input and output terminals. The conductive connection pads are placed on insulating supports adapted to be clamped by the clamps, themselves connected in pairs to form conductive bridges. The bridges are associated with drive means enabling them to take a first position in which they provide the connection between two areas of the support, and a second position in which they provide the connection between two other areas of the support; the ranges are arranged so that between the first and the second position, there is inversion of the connection between input and output terminals.

Preferably, the drive means of the bridges comprise one or two rotatable bars about an axis, said bars being advantageously provided with cavities housing a non-active portion of the clamps and links between two clamps to form said bridges. The conductive pads are placed on an insulating support per bar; the support is such that, regardless of the relative rotational position of the bar, it is clamped between the clamps connecting bridges.

In the preferred embodiment, two bars each comprise a bridge of clips, preferably diametrically opposed, and separated from each other by a rotary shaft along the axis. The two supports are each provided with three conductive areas: one of the three ranges is adapted to be in contact with a bridge clamp in the first and 2`13LPu in the second position; the two other conductive areas of the first bar are connected, advantageously by a fixed conductor, to the other two conductive pads of the second bar for connection to the same terminal.

The inversion assembly is coupled to actuating means in a device according to the invention. According to preferred embodiments, the actuating means of (the) bar (s) are rotatable and unidirectional, the first and second position of the clamp bridges are separated by 90 ° from each other. The actuating means are advantageously coupled to control means of the inversion device, and / or to sensors making it possible to ensure the security and / or the optimization of the inversion.

BRIEF DESCRIPTION OF THE FIGURES Other advantages and features will become more clearly apparent from the following description of particular embodiments of the invention, given by way of illustration and in no way limiting, represented in the appended figures.

FIG. 1, already described, illustrates a motor starter equipped with a phase inverter.

Figures 2A and 2B show the first and second positions of an inversion assembly for a device according to one embodiment of the invention.

Figure 3 shows an inversion assembly according to another embodiment. Figure 4 shows an inverting device according to one embodiment of the invention. DETAILED DESCRIPTION OF A PREFERRED EMBODIMENT

In an inverter device 200 according to the invention, the contacts between the phase conductors L 1, Ti 2 are produced by means of clamps 205, which makes it possible, without adding additional parts, to ensure a contact pressure when of the passage of the current. The clamps 205, shown diagrammatically in FIG. 3, can be of conventional design, such as for example used in FR 2 668 851: the choice of this solution thus makes it possible to reduce the logistical costs. Moreover, insensitive to shocks and vibrations, the clamps 205 of length L and spacing d see their contact force increase in case of short-circuit current Icc according to the formula F = (12/4) x (μo • L • rd). This makes it possible to dispense with any spring or other intended to prevent the reopening of the contacts during repulsion due to the passage of short-circuit current; in particular, the cost of the coil or other magnetic circuit disappears.

According to the invention, the clamps 205 ensuring the contact are not loaded in opening / closing during phase changes, which makes it possible to optimize their service life, to reduce the wear of the components in contact, and to control the contact pressure at a level sufficient to pass the rated current. The inversion principle according to the invention is based on a sliding between the clamps 205 of alternating conductive and insulating sectors of the same part; this solution offers for another advantage a cost reduction generated by the fact that the clamps and the conductive sectors are devoid of silver pellets.

In particular, the terminals 206, 208 of the inverter 200, that is to say the phases to be reversed, are coupled to a fixed conductive circuit of the inverting element 210 according to the invention, which furthermore comprises the contact clamps 205, placed on a movable element allowing, according to its position, to connect between them different conductive areas of the circuit. Thus, as schematically illustrated in Figures 2 and 3, the clamps 205 are rotatable about an axis AA and are pairwise associated to form contact bridges 215; depending on the position about the axis AA, the bridges 2151, 2152 couple two phases or two other phases.

The means for driving the clamps 205 in rotation comprise at least one insulating bar 220 rotating about the axis AA; advantageously, the clamps 205 are housed in adapted cavities 222 of the bar 220, and the bridges 215 are formed by a connecting conductor 224 between two clamps 205; the conductor 224 may be integrated with the bar 220 or surface; the connecting conductor 224 may be unitary with the 2713 LPu clamps 205 (see Figure 3). Depending on the desired size, the power of the inverter 200 and the isolation distances to be respected, the clamps 205 may be part of one (FIG. 2) or two (FIG. 3) bars 220. In the case where two 2201 bars, 2202 are chosen, it is advantageous to separate them along the axis AA by a shaft 226, so as to increase the isolation distances.

The inversion assembly 210 according to the invention is completed by a support 230 by bar 220 of clamps 205, said support 230 being traversed by the bar 220, gripped by the clamps 205 and adapted to allow their rotation. The supports 230 are insulating and provided with conductive pads 232 which are connected to the phases to be reversed; the conductive pads 232 are separated from each other by a sufficient isolation distance, but remain sufficiently close to the axis AA so that the clips 205 of the bridges 215 can enclose them in pairs. Advantageously, the insulator 230 is polytetrafluoroethylene to reduce friction, the pads 232 are copper, and the support 230 has a substantially flat surface despite its double composition to reduce the wear of the clamps 205 and / or pads 232.

It is advantageous that the rotation of a quarter turn of the bar 220 causes the phase inversion. In the presence of a single bar 220 (FIG. 2), the clamps 205 then form bridges 2151, 2152 covering a quarter of a circle of the bar 220, and the support 230 can thus be provided with four conductive pads 232 at 90.degree. one of the other, substantially at the clamping end of the clamps 205, and alternately coupled by conductors to the input and output terminals. Thus, as illustrated in FIG. 2A, in a first position of the bar 220, the first clamp bridge 2151 connects the conductive pads corresponding to the supply phase LI and the motor phase T1, and the second bridge 2152 connects the tracks. corresponding to the power supply phases L2 and T2 of the motor 2. In the second position illustrated in FIG. 2B, the first bridge 2151 connects the supply phase L1 to the phase T2 of the motor 2, and the second bridge 2152 connects the phase L2 supply to the phase Ti of the motor 2. Thus, between the first and the second position, there has been inversion of the connection between the phases; to return to the first position, it is possible to actuate the bar 220 in the opposite direction or to continue the rotation in the same direction by a quarter turn. 271.3 LPu In the preferred embodiment illustrated in Figure 3 and wherein two coaxial bars 2201, 2202 are each provided with two clamps 205, they are preferably substantially diametrically opposed, and the two supports 2301, 2302, also provided with four conductive zones at 90 ° to each other, furthermore comprise a connection zone 234 interconnecting two adjacent conductive zones, so as to form a conductive portion 232 'which is clamped by a clamp 205 regardless of the relative position of the contact bridge 220, and to keep two conductive pads 232A, 232B, isolated from one another, which are clamped by a clamp 205 in only one of the two positions. The conductive pads 232A, 232B of each support 230 are connected, by a first conductor 236, to the input terminals 206 (respectively output) of the inverter 200, and each output terminal 208; (respectively input) of the inverter 200 is connected by a second conductor, preferably of the same type, to the conductive portion 232 'of a support 230. The input terminals 206; (respectively output) are thus connected to two conductive pads 232A ;, 232B; two different supports 2301, 2302: a conductor-like element 238A, 238B can make this connection at the supports 230, but other means are possible.

By analogy with FIGS. 2, in the first illustrated position, the first clamp bridge 2151 connects the first conductive portion 232'1 connected to the supply phase L1 and the first conductive pad 232A1 corresponding to the phase Ti of the motor 2; the second bridge 2152 connects the second conductive portion 232'2 corresponding to the phase L2 and the second conductive region 232 'corresponding to the phase T2 of the motor 2. In the second position (not shown), the first bridge 2151 connects the first part conductive 232'1 corresponding to the phase L1 and the second conductive region 232B1 corresponding to the phase T2 of the motor 2; the second bridge 2152 connects the second conductive part 232'2 corresponding to the phase L2 and the conductive region 232B2 corresponding to the phase T1 of the motor 2. Here again, there is a reversal of the connection between the phases between the first and the second phase. second position; the return of the second to the first position can also be carried out by rotation in opposite direction or continuation of the rotation in the same direction. 2'7 k_Pu Please note that the illustrated configurations can be modified. In particular, contrary to the diagram of FIG. 3, the two clamp bridges 215 may be orthogonal, in particular according to the mounting facilities of the conductors 236, 238; likewise, the clamps 205 may not be diametrically opposed. More generally, a rotation of 120 ° or other may be considered to pass from the first to the second position, the number of conductive pads being adapted accordingly.

The rotation about the axis AA can be carried out by any means of motor or electromagnet type; the actuating means 240 may be bistable, or it may be monostable and possibly combined with a rattle and rack system. In addition, the pressure exerted by the clamps 205 is very slightly dependent on the short-circuit withstand capability, which makes it possible to use a low effort actuator 240. In particular, in a preferred embodiment illustrated in FIG. 4, the drive is performed by a bistable electromagnet coupled to a rack. As illustrated in FIG. 4, the inverting assembly 210 is housed in a housing 242, which is preferably similar in shape and size to those of the protection devices 10 of line 1 and the same mounting system. including a DIN rail. The housing 242 conventionally comprises three input terminals 206 and three output terminals 208; an input terminal 2063 and an output terminal 2083 are interconnected by a fixed conductor 244, for example a braid or a copper lamella; the other terminals 2061, 2062, 2081, 2082 are connected to the conductive pads 232 of the inverting assembly 210. The conductors 236 connecting the terminals 206, 208 of the inverter 200 are fixedly mounted relative to the housing 242, and the shaft 226 is put in place at a guiding system 246 allowing a Stability of the inverting assembly 210. Preferably, the supports 230 of the inverting assembly 210 are close to each side wall of the housing 242 to increase the isolation distances and to release the maximum of space in the center of the housing. housing 242.

The design of the contact according to the invention, by clamping clamps 205, makes it possible to dispense with any spring or other, intended to prevent the reopening of the contacts during repulsion due to the passage of short-circuit current; in particular, the cost of the coil or other magnetic circuit disappears. Furthermore, the actuating means 240 of the inverter 271.3 LPu 0 may be of reduced size, and located in the residual space between the two bars 220: it is thus possible to integrate the inversion assembly 210 according to the invention in a housing 242 of width 1 = 45 mm for applications up to 50 kA.

The housing 242 of the inverter 200 according to the invention advantageously comprises an electronic control system 250 for activating the actuating means 240 of the bars 220 in a controlled manner. The simplicity of the movement involving the phase inversion allows optimal management of the inversion time, so that the power of the actuating means 240 and their consumption can be rationalized. It is also possible to integrate sensors 252 making it possible to reflect the situation of the inverter 200 (position of the clamps 205, state of charge on the lines 236, 244) and to act on the actuating means and / or in particular by preventing reverse charging in the manner of the auxiliary contacts. For example, a position sensor 252 directly operated by cams present on the rotary shaft 226 can give the relative position of the clamps 205 by determining the rotation.

The device 200 according to the invention thus makes it possible to perform a two-phase inversion function by a limited number of components, associated with a limited number of parts in relative movement, reducing the cost of mounting the device. What's more, the design allows the use of simple shaped parts, which can be used multiple times, further reducing the costs of achieving

Although the invention has been described with reference to a device for reversing two phases when starting a three-phase motor, it is not limited thereto: other elements may be concerned by the invention. In particular, the device according to the invention is suitable for reversing the direction of operation of three-phase asynchronous motors. The device according to the invention can also be adapted, for example by adding a third clamp bridge and a third bar, for the passage from the "star" configuration to the "triangle" startup configuration of the three-phase motors or for the passage on a second voltage source; conversely, the design of the device according to the invention is adapted for a reversal of the DC current, by eliminating the third phase.

2713 LPu

Claims (10)

REVENDICATIONS1. A phase inversion device (200) comprising: - a first and a second input terminal (206;); a first and a second output terminal (208;); an inverting element (210) comprising two bridges (215) of two conductive clamps (205), at least one insulating support (230) adapted to be clamped between the clamps (205) of the bridges (215), and means (220) for driving the bridges (215) in rotation about an axis (AA), the clamps (205) remaining clamped around the support (230); conductive pads (232) located on the at least one support (230) so that they can be gripped by the clamping collars (205); conductors (236) connecting the terminals (206; 208;) to the conductive pads (232); - Actuating means (240) for the drive means (220) of the bridges (215); the inversion assembly (210) being adapted for the bridges (215) to assume a first position in which the first, respectively second bridge (2151) connects a first and a second conductive pad (232 ', 232A) and a second position in which the first, respectively second, bridge (2151) connects a first and a third conductive pad (232 ', 232B), said third pad (232B) being different from the second pad (232A). 2. Device according to claim 1 wherein the first and second positions are separated by 90 °. 3. Device according to claim 2 wherein the actuating means (240) comprise a unidirectional rotary motor. 4. Device according to one of claims 1 to 3 wherein the inverting element (210) comprises two coaxial bars (2201, 2202), each bar (220;) 2713 LPsupporting a pair of clamps (215i), and two supports (230i) each having three conductive pads (232Ai, 232Bi, 232'i). 5. Device according to claim 4 wherein two conductive pads (232A1, 232B1) of the first support (2301) are connected by a fixed conductor (238A, 238B) to two conductive pads (232A2, 232B2) of the second support (2302). 6. Device according to one of claims 4 or 5 wherein the clamps (205) of each bridge (215) are diametrically opposed and housed in cavities (222) of each bar (220). 7. Device according to one of claims 4 to 6 wherein the two bars (220i) are connected by a shaft (226) and the actuating means (240) are coupled to the shaft (226) between the two bars (220i). 8. Device according to one of claims 1 to 7 further comprising a third input terminal (2063) and a third output terminal (2083) interconnected by a conductor (244). 20 9. Device according to one of claims 1 to 8 further comprising control means (250) actuating means (240). 10. Device according to one of claims 1 to 9 further comprising a sensor (252) for determining the position of the clamps (205) about the axis (AA). 25 2713 LPu