FR2806522A1 - MAGNETIC TRIPPING DEVICE, ESPECIALLY FOR CIRCUIT BREAKERS, AND ELECTRICAL PROTECTION DEVICE INCLUDING SUCH A DEVICE - Google Patents

Abstract

The invention relates to a magnetic tripping device (5), in particular for a circuit breaker D, comprising at least one so-called movable core associated with a rod, the assembly being slidably mounted inside a sheath (7), an induction coil (11) through which the current to be monitored and able to generate, when this current exceeds a certain threshold, a magnetic field capable of causing the moving core and the rod to move between a rest position and a position wherein an end forming a striker of the rod controls the triggering of the mechanism (3) for opening and closing the contacts (1, 2), a means for channeling the magnetic field generated by the coil (11) and a horn of arc (13) electrically connected to the fixed contact and able to guide the arc during breaking in the direction of the extinguishing chamber C. The means for channeling the magnetic field consists of the arc horn (13) itself , said horn (13) being arranged in a manner q ue the magnetic flux generated by the coil (11) from the movable core successively passes through the fixed contact (1) of the device and the arc horn (13) before joining the movable core.

Description

MAGNETIC TRIGGERING DEVICE, PARTICULARLY FOR

  CIRCUIT BREAKER, AND ELECTRICAL PROTECTION APPARATUS

COMPRISING SUCH A DEVICE.

  The present invention relates to a magnetic trip device in particular

  for a circuit breaker and an electrical protection device comprising such a device.

  Low-voltage circuit breakers generally comprise, in a manner known per se, magnetic tripping means capable of causing tripping of the circuit breaker mechanism during an abrupt rise in current following for example a short circuit, and thermal tripping means suitable for triggering the

  circuit breaker mechanism in the event of an overload resulting in a slow rise in current.

  According to a known embodiment described in patent documents FR 2 630 582 and FR 2 368 139, these magnetic tripping means comprise an induction coil mounted around a rod forming a striker associated with a movable core, the assembly being mounted sliding inside a sheath, the rod sliding inside a fixed core fixed inside the sheath. The rod is supported, by one of its ends, on the movable core. A spring mounted around the rod, is interposed between the two cores and is suitable for

  recall the two cores in a separate position, in the release position of the trigger.

  This device further comprises a carcass mounted around the assembly constituted by the cores and the striker, and electrically connected to the fixed contact of the device, said carcass being able to channel the magnetic fields generated by the coil. In operation, when

  from a sudden rise in current, a magnetic field is generated by the coil.

  When the value of the current exceeds a predetermined threshold, the movable core moves in the direction of the fixed core against the force of the spring and drives in its movement the rod, which causes the unlocking, by the striker formed at the end of the rod,

  circuit breaker mechanism and contact opening.

  However, this type of magnetic trigger is particularly bulky, taking into account on the one hand, the presence of the carcass and, on the other hand, the large number of parts used. It follows from this large number of parts that the number of positioning constraints is relatively high. In particular, the magnetic threshold is dependent on the value of the air gap between the two fixed and mobile cores and the value of this air gap must

therefore be set precisely.

  The present invention overcomes these drawbacks and proposes a magnetic trip device of simple design, of reduced bulk, and the operation of which has been made more reliable, as well as an electrical protection device such as a circuit breaker.

comprising such a device.

  The present invention relates to a magnetic trip device, in particular for an electrical protection device such as a circuit breaker, capable of causing a trip of the opening mechanism of the fixed and movable contacts of the device during a sudden rise in the current following, for example, a short circuit, comprising at least one core known as a mobile core associated with a rod, the assembly being slidably mounted inside a sheath, a coil crossed by the current to be monitored and capable of generating , when this current exceeds a certain threshold, a magnetic field capable of causing the displacement of the mobile core and of the rod between a rest position and a position in which an end forming a striker of the rod controls the triggering of the aforementioned mechanism, a means for channeling the magnetic field generated by the coil and an arc horn electrically connected to one of the contacts and capable of guiding the rc during the cut-off in the direction of the arc extinguishing chamber, this device being characterized in that the means for channeling the magnetic field consists of the aforementioned arc horn, said horn being arranged so that the magnetic flux generated by the coil leaving the movable core successively crosses the fixed contact of the device and the arcing horn

before joining the mobile nucleus.

  According to a particular embodiment of the invention, this device exclusively comprises a

moving core.

  According to another characteristic, the above-mentioned rod is integral with the movable core.

  The present invention also relates to an electrical protection device, in particular a circuit breaker, comprising the preceding characteristics taken alone or in combination. But other characteristics and advantages of the invention will appear better in the

  detailed description which follows and refers to the appended drawings given only as a

  examples and in which: FIGS. 1 and 2 are two schematic views illustrating respectively a magnetic trigger device according to the prior art and a magnetic trigger device according to the invention, FIG. 3 is a partial perspective view, illustrating the inner part of a circuit breaker equipped with a magnetic trip device according to the invention, FIG. 4 is a plan view of the previous figure, and

  Figure 5 is a sectional view along V-V of the previous figure.

  Figures 3 to 5 show a low voltage electrical circuit breaker D intended to be used to protect an electrical circuit against overloads or short circuits. This circuit breaker D mainly comprises, in a manner known per se, a pair of separable contacts 1,2 respectively fixed and movable, a control mechanism 3 for opening and closing of the contacts actuated by a lever 4, an electromagnetic trip device 5 intended for trip the mechanism 3 of the circuit breaker D and thus cause the opening of the contacts 1,2 when a short-circuit current appears, and a thermal trip 6 (not shown) able to trip the mechanism 3 during the appearance of a current overload. In Figure 1, we see a magnetic trigger device 5, or trigger, according to the prior art. This device 5 comprises a so-called fixed core 6, fixed in a sheath 7, a

4 2806522

  movable core 8 slidably mounted inside said sheath 7, a rod 9 slidably mounted inside the fixed core 6 parallel to the sliding direction of the movable core 8, a spring 10 interposed between the two cores 6,8 and a induction coil 1 1 mounted around the sheath 7. This device further comprises a carcass 12 mounted around the sheath 7 so as to channel the magnetic flux generated by the coil 11, as well as an arc horn 13 electrically connected to the contact fixed 1 of the circuit breaker and used to guide the arc in the direction of the extinguishing chamber C during breaking. The aforementioned rod 9 comprises a first end 9a bearing on the movable core 8 and a second end 9b forming a striker. In operation, when the current is above a certain threshold, the coil 11 generates a magnetic field capable of counteracting the force of the spring 10 and of displacing the movable core 8 in the direction of the fixed core 6. This movable core 8 then drives in its movement the striker rod, which acts on the trigger bar 14 of the device and causes the mechanism 3 to be unlocked. The flow generated by the coil 11 passes through the carcass 12 (as illustrated by the arrows), and is channeled by said carcass 12 so as to obtain a maximum efficiency of the magnetic field. During cutting, the arc current flows through the arc horn 13 and goes towards the arc extinguishing chamber C. The breaking power associated with

  such a device is around 20kA.

  Unlike the device of the prior art, the magnetic trigger device 5 according to the invention, as illustrated in FIGS. 2 to 5, does not include a carcass for channeling the magnetic field. This function is performed by the arcing horn 13 itself secured to the fixed contact which, when the coil 11 generates a magnetic field, is crossed by the corresponding magnetic flux and therefore channels this flux. According to the embodiment described in Figures 2 to 5, the device no longer has a fixed core, from which it follows that the magnetic threshold is independent of the air gap between fixed core and movable core unlike what was the case in l prior art. Thus, the expression "exclusively a mobile core" must be interpreted as meaning that the device does not include a fixed core. In this embodiment, the spring 10 is interposed between a part of the sheath

  7 and the mobile core 8. The rod 9 is integral with the mobile core 8.

  We see in the figures that the arc horn is continuous and extends parallel to the axis of the coil over a certain length, which allows the arc to perform only one switching. The operation of the device is the same as that of the device of the prior art and will therefore not be described again, except that on the one hand, the movable core 8 is no longer attracted by the fixed core 6, l magnetic force generated by the coil 11 being sufficient to

  move the movable contact 8. The breaking capacity is limited to 10 kA.

  Thanks to the invention, a magnetic tripping device has therefore been produced which is simple, economical and of reduced bulk, taking into account a smaller number of parts used. It also results from this reduction in the number of parts, a reduction in the number of positioning constraints making the operation of the device more reliable. In particular, the magnetic threshold being independent of the air gap, the latter no longer needs to be adjusted precisely. Also, the length of the moving core can

  be reduced taking into account that it no longer cooperates with the carcass.

  Of course, the invention is not limited to the embodiments described and illustrated which

  have been given by way of example only.

  On the contrary, the invention includes all the technical equivalents of the means described

  as well as their combinations if these are carried out according to his spirit.

Claims (7)

  1. Magnetic tripping device, in particular for an electrical protection device such as a circuit breaker, capable of causing a tripping of the mechanism for opening the fixed and movable contacts of the device during an abrupt rise in current following, for example, a short circuit, comprising at least one core, said mobile core associated with a rod, the assembly being slidably mounted inside a sheath, a coil crossed by the current to be monitored and capable of generating, when this current exceeds a certain threshold, a magnetic field capable of causing the displacement of the mobile core and of the rod between a rest position and a position in which an end forming a striker of the rod controls the triggering of the aforementioned mechanism, a means for channeling the field magnetic generated by the coil and an arc horn electrically connected to one of the contacts and capable of guiding the arc during the cut in direction d e the arc extinguishing chamber, characterized in that the means for channeling the magnetic field consists of the aforementioned arcing horn (13), said horn (13) being arranged so that the magnetic flux generated by the coil (11) starting from the movable core (8) successively crosses the fixed contact (1) of the device and the arcing horn (13) before joining the movable core (8).   2. Device according to claim 1, characterized in that the arc horn (13) is connected   electrically on fixed arcing contact (1).   3. Device according to claim 2, characterized in that the aforementioned arc horn (13)   comprises a continuous arc horn extending parallel to the axis of the coil (8).   4. Device according to any one of claims 1 to 3, characterized in that it   exclusively comprises a movable core (8).   5. Device according to any one of claims 1 to 4, characterized in that the rod   above (9) is integral with the movable core (8).   6. Electrical protection device comprising a triggering device   magnetic according to any one of the preceding claims.   7. Circuit breaker comprising a magnetic trip device according to one   any of claims 1 to 5.