SERIES-CONNECTED TWO-STAGE ELECTRICAL PROTECTION DEVICES

Description

TECHNICAL FIELD

[0001] The present invention relates to a set of two-level electrical protection devices connected in series, the first level comprising a circuit breaker called the first or upstream circuit breaker, the second level comprising one or more circuit breakers called the second or downstream circuit breakers, mounted in parallel with each other, the downstream circuit breakers having a lower rating than the first circuit breaker, each circuit breaker comprising for each of the phases, a cut-off block crossed by a current line on which are placed two separable contacts as well as a current measurement sensor, means for manual or remote-controlled actuation of the contacts, means for automatic opening of the contacts controlled by a trigger, said trigger being controlled by the aforementioned current sensor,and comprising means for adjusting the long-time tripping curve in inverse time as well as the short-time tripping curve with a non-tripping time, the tripping devices of the so-called second circuit breakers further comprising so-called instantaneous protection means allowing the actuation of the tripping device associated with these so-called second circuit breakers when the current reaches a threshold called the DIN threshold for instantaneous tripping of these second circuit breakers., STATE OF PRIOR ART

[0002] Such sets of electrical protection devices are known which can simultaneously provide three functions, namely: extreme cut-off performance by connection between the two stages of low-voltage cut-off devices, total selectivity between these two stages, and ultra-fast protection of the upper stage in the event of an intermediate fault between the two stages.

[0003] However, these three functions are difficult to reconcile at a level of performance corresponding to that which must be achieved in low voltage cut-off device systems intended primarily for auxiliary panels on very high power low voltage boats, typically powers greater than 100 KA and 690 V.

[0004] As a general rule, the techniques of filiation and selectivity are often incompatible for high current values ​​with voltages greater than 525V.

[0005] Document FR 3 069 951 describes a set of electrical protection devices comprising the characteristics of the preamble of claim 1.

[0006] The present invention solves these problems and proposes a set of low voltage electrical protection devices intended for use in very high power low voltage applications, so as to ensure both extreme breaking performance by connection, total selectivity, and ultra-fast protection of the upper stage in the event of an intermediate fault between the two stages. STATEMENT OF THE INVENTION

[0007] To this end, the present invention relates to a set of electrical protection devices according to claim 1.

[0008] According to a particular characteristic, the or each trigger comprises means for adjusting the long-time tripping curve in inverse time for currents less than substantially 10 times the nominal current In, as well as means for adjusting the short-time tripping curve, with a non-tripping time of 20 ms, for currents with a value between 1.5 and 10 times the nominal current.

[0009] According to another characteristic, the circuit breakers are limiting circuit breakers.

[0010] According to another feature, the aforementioned predetermined current value and threshold are respectively 10 times the nominal current In and 8000lux.

[0011] According to another characteristic, the so-called first circuit breaker-limiter has a rating between 800 and 1000A, while the so-called second circuit breaker-limiters have a rating between 40A and 250A.

[0012] According to another characteristic, the so-called first circuit breaker has a caliber of 800A, while the so-called second circuit breaker has a caliber of 100A.

[0013] According to another characteristic, the instantaneous tripping threshold value of the second circuit breakers is approximately 11 kArms.

[0014] According to another characteristic, the aforementioned upstream circuit breaker includes a pyrotechnic propellant intended to allow ultra-rapid tripping in the presence of an inter-phase arc fault in the area between the two stages.

[0015] According to another characteristic, the aforementioned optical sensor comprises a discriminating optical fiber, said optical fiber comprising a fluorinated glass fiber having at its ends a treatment intended to block waves above 450 nm.

[0016] The present invention also relates to a set of two-level electrical devices, characterized in that it is used in auxiliary switchboards of boats with power greater than 100KA / 690V.

[0017] But other advantages and characteristics of the invention will appear better in the detailed description which follows and refers to the appended drawings given solely as examples and in which: BRIEF DESCRIPTION OF THE DRAWINGS

[0018] [ Fig. 1 ] - There Figure 1 is a representation of an electrical diagram illustrating a set of low voltage two-level electrical devices according to the prior art, [ Fig. 2 ] - There Figure 2 is a functional diagram illustrating an electronic circuit breaker belonging to a set of devices according to the prior art, [ Fig. 3 ] - There Figure 3is a graphical representation illustrating two tripping curves corresponding respectively to those of two circuit breakers, respectively upstream and downstream, belonging to the set of devices according to the aforementioned prior art, [ Fig. 4 ] - There Figure 4 is a representation of an electrical diagram illustrating a set of low voltage electrical devices according to a particular embodiment of the invention, [ Fig. 5 ] - There Figure 5 is a functional diagram illustrating an electronic circuit breaker belonging to a set of devices according to a particular embodiment of the invention, and [ Fig. 6 ] - There Figure 6 is a graphical representation illustrating two tripping curves corresponding respectively to those of two circuit breakers, respectively upstream and downstream, belonging to the set of devices according to the aforementioned embodiment of the invention. DESCRIPTION OF A PARTICULAR MODE OF CARRYING OUT THE INVENTION

[0019] On the Figure 1, we see a set E of low voltage electrical devices, or system of devices, comprising two levels a,b connected in series, according to the prior art.

[0020] This assembly E includes a limiting circuit breaker 1, called the upstream or first circuit breaker, advantageously having a rating of 800 A and comprising as illustrated on the Figure 2, a cut-off block 2 comprising a mechanism 3 for cutting the circuit breaker contacts, a mechanism 4 for manually or remotely actuating the circuit breaker contacts, a tripping mechanism 5 of the electromagnetic coil type, a current sensor 6 per phase, an electronic trip unit 7 making it possible to adjust the long-time tripping curve in inverse time for currents lower than, advantageously, ten times the nominal current In, to adjust the short-time tripping curve, with a non-tripping time of, advantageously, 20ms, for currents between, advantageously, 1.5 times and 10 times the nominal current, and instantaneous protection means integrated into the circuit breaker and having a fixed threshold of, advantageously, 22kA (11kA rms).

[0021] This set of devices E also includes one or more so-called downstream or second limiting circuit breakers 8, mounted in parallel with each other, these limiting circuit breakers 8 being mounted in series with the aforementioned upstream limiting circuit breaker 1.

[0022] These limiting circuit breakers, called downstream 8, have a rating advantageously between 40A and 250A, and comprise, in the same way as for the upstream circuit breakers 1, a limiter-type breaking part, a manual or remote-controlled actuation mechanism, a tripping mechanism comprising an electromagnetic coil, a current sensor per phase, an electronic trip unit, and integrated, non-adjustable instantaneous protection means, having a fixed threshold of, advantageously, 3000A.

[0023] The operation of such a circuit breaker according to the prior art will be described in the following with reference to the figures 1 to 3 .

[0024] On the Figure 3, the graphic representation illustrates the two tripping curves c,d respectively of the two upstream and downstream circuit breakers, with on the ordinate the tripping time T, in seconds, and on the abscissa, the current I, in amperes, flowing through the circuit on which the sets of circuit breakers are placed.

[0025] We will first deal with the case of the appearance of a fault in position 1 on the Figure 1 , that is to say downstream of the circuit breaker called second 8.

[0026] In area X, shown on the Figure 3 , the current flowing through the device is lower than the DIN threshold of the first circuit breaker 1. Only the second circuit breaker 8 trips, thanks to the time selectivity due to the 20ms time delay associated with the first circuit breaker 1, which means that it is the second circuit breaker 8 which trips first.

[0027] In zone Y, the current value is greater than the DIN threshold, i.e. the instantaneous tripping threshold S of the first circuit breaker 1, the two circuit breakers 1, 8 trip, there is a connection when the cut-off performance is greater than the maximum cut-off performance of the second circuit breaker 8. There is no selectivity because the upstream circuit breaker 1 has tripped.

[0028] It should be remembered that selectivity is the coordination of automatic cut-off devices so that a fault occurring at any point in the network is eliminated by the circuit breaker placed immediately upstream of the fault, and by it alone. Filiation is the technique which consists of increasing the breaking capacity of a circuit breaker by coordinating it with another protective device placed upstream.

[0029] We will now deal with the case of the appearance of a high short-circuit fault in position 2, i.e. downstream of the first circuit breaker 1 and upstream of the second circuit breaker 8.

[0030] In this case, the limiting circuit breaker called first 1 limits the current by repulsion of the contacts, and its trigger is activated as soon as the current value exceeds the DIN threshold of the instantaneous trigger. The trip coil is activated, commands the opening of the mechanism, and confirms the opening of the main contacts.

[0031] On the Figure 4 , a set F of devices according to a particular embodiment of the invention has been shown.

[0032] This set of devices according to the invention comprises, as in the prior art, a first limiting circuit breaker 1, called the upstream circuit breaker, and several limiting circuit breakers called seconds or downstream circuit breakers 8, mounted in parallel with each other, this or these circuit breakers called seconds 8 being placed in series with the first circuit breaker 1.

[0033] The second circuit breakers 8 are constituted in the same manner as in the prior art.

[0034] As illustrated more particularly on the Figure 5, the upstream circuit breaker 1 according to the invention comprises, in addition to the elements already present in the upstream circuit breaker according to the prior art, a discriminating optical sensor 9 capable of controlling an additional control unit 10, this unit 10 being capable on the one hand, of receiving information from the current measurement sensor 6 belonging to the cut-off block 2, and on the other hand, of controlling the opening coil of the tripping mechanism 5 of the contacts of the so-called first circuit breaker 1.

[0035] Thus, by the technical means listed above, the trigger of this first circuit breaker 1 differs from that of the prior art in that it is broken down into a first and a second tripping chain. The first tripping chain comprises means for adjusting the long-time delay tripping curve in inverse time for currents less than 10 times the nominal current In, for adjusting the short-time delay tripping curve with a non-tripping time of, advantageously, 20 ms adjustable from, advantageously, 1.5 to 10 times the nominal current. This first tripping chain does not comprise integrated instantaneous protection means having a fixed threshold.

[0036] The second tripping chain comprises means for simultaneously measuring the current level and the maximum threshold of light emitted by the optical sensor 6, which sensor discriminates light between 300 and 450 nm by eliminating visible and infrared type lights so as to only take into account the light emitted by the arc on the busbars and to eliminate the characteristic light of gas jets emitted by the low voltage circuit breakers during a cut.

[0037] The operation of such a set of devices will be described in the following with reference to the figures 4 to 6 .

[0038] We will first deal with the case of the appearance of a fault in position 1, as illustrated in the Figure 4 , that is to say downstream of the circuit breaker called second 8,

[0039] In an X zone, as defined on the Figure 6, corresponding to a current value lower than the DIN S threshold of the first limiting circuit breaker 1, only the second circuit breaker 8 trips, there is, as in the prior art, time selectivity.

[0040] In zone Y, the current value is higher than the DIN S threshold of the first limiting circuit breaker 1. In this case, only the so-called second circuit breaker 8 trips. In the same way as in the prior art, there is a connection when the cut-off performance is higher than the maximum cut-off performance of the second circuit breaker 8 thanks to the help of the repulsion of the contacts of the cut-off block 2 of the so-called first circuit breaker 1.

[0041] In this case, there is selectivity between the two circuit breakers, because the first circuit breaker 1 did not trip on the one hand, because this first circuit breaker 1 does not include so-called instantaneous tripping means, and on the other hand, because the light sensor 9 eliminated the light generated by the escape of the cut-off gases coming from the downstream circuit breaker 8. Indeed, due to this elimination, the second trip chain of the upstream circuit breaker 1 did not cause the upstream circuit breaker 1 to trip because the light measurement carried out by the additional control unit 10 did not exceed the threshold value. Indeed, during a fault downstream of the second circuit breaker 8, this circuit breaker, by interrupting the current, emits, via the jets of ionized gas exiting through the exhausts, light in the visible and infrared ranges, this corresponding to a wavelength greater than 450nm.If the light sensor were active for these wavelength values, selectivity would not be ensured. The so-called first circuit breaker 1 would be opened by the activation of the optical sensor 9 and the current measurement.

[0042] We will now study the case of the appearance of a high short-circuit fault in position 2 on the Figure 4 , that is to say downstream of the first circuit breaker 1 and upstream of the second circuit breaker 8. In this case, the limiting circuit breaker called first 1 limits the current by repulsion and the first tripping chain of its trip unit 7 is activated when the light is greater than 8000 lux and the current value greater than a predetermined value, for example 10In, that is to say ten times the nominal current In. The coil of the main actuator is activated, commands the opening of the mechanism, and confirms the opening of the main contacts. There is self-protection of the circuit breaker in the event of a fault.

[0043] It should be noted that since the so-called second 8 circuit breaker is a limiter type device, its electrodynamic resistance is low (approximately 15 times the nominal current). This is essential so that it can assist in breaking as early as possible during breaking tests with performances higher than the short-circuit currents that can be supported alone by the downstream circuit breaker, which is also a limiter type.

[0044] Thus, the breaking energy can be distributed between the two circuit breakers in series 1.8. The value of the instantaneous tripping threshold S is set to a value slightly lower than the electrodynamic withstand in order to ensure self-protection of the circuit breaker. When the current is higher than the electrodynamic withstand, it must trip instantly, for example before 10 ms.

[0045] It should be noted that according to another embodiment, the downstream limiting circuit breaker 8 can be a magnetothermal technology circuit breaker without an electronic part.

[0046] It will also be noted that this optical sensor 9 will advantageously be coupled to a pyrotechnic propellant, acting only in the event of a fault in priming between phases in the area located between the two levels.

[0047] Thus, according to the invention, the upstream limiting circuit breaker 1 is equipped with a double tripping chain. A first tripping chain protects against overload currents up to 10 times the nominal current, approximately 12 kA for an IN of 800A, with a time delay of 20ms for this so-called instantaneous value, 20ms being greater than the breaking time of the downstream circuit breaker 8 at this performance level of 12kA RMS. A second tripping chain activated by a current measurement greater than 10In and a light measurement from an optical sensor blocking wavelengths greater than 450nm, these lengths being characteristic of the gas jets emitted by low-voltage circuit breakers during a break.

[0048] Thanks to this double tripping chain, we obtain for a fault appearing in position 1, on the one hand, an extreme breaking performance by connection between the two stages of low voltage breaking devices, by cooperation of the two breaking assemblies, and on the other hand, a total selectivity between these two stages, characterized by a non-tripping of the upstream circuit breaker.

[0049] For a fault appearing in position 2, we obtain ultra-fast protection of the upper floor and the associated busbars, thanks to the second tripping chain.

[0050] This is achieved by producing very moderate external manifestations, through better absorption and better distribution of the cut-off energy between the two stages.

[0051] To obtain ultra-fast protection in the event of an internal fault occurring between the two stages of the installation, the upstream circuit breaker 1 can advantageously be equipped with a pyrotechnic propellant, acting only in the event of a fault in the initiation between the phases in the area located between the two stages. It should be noted that in the case of a panel of the so-called "fishbone" type as illustrated in the Figure 4 , only one discriminating optical sensor is required. It will be positioned opposite the upstream circuit breaker, at the height of the vertical bars connecting to the upstream device and to which the lower-rated downstream devices are connected. Indeed, if an arc occurs on the vertical bars, the electrodynamic forces will push the arc away from the transformer.

[0052] It should be noted that the discriminating optical sensor can be replaced by a discriminating optical fiber, i.e. a fluorinated glass fiber with treatment at the ends blocking waves above 450nm.

[0053] The invention is advantageously applicable to low-voltage cut-off device systems intended primarily for auxiliary panels on very high-power low-voltage boats, typically for powers greater than 100 KA 690V. Indeed, for critical installations such as boats, it is essential to ensure selectivity between the different stages. An incident on one load must not render the other loads inoperative.

[0054] But, it can be applied advantageously to all areas requiring this level of simultaneous performance in filiation and selectivity, for example in the field of renewable energies, with increasingly increased performance.

[0055] This system, comprising two stages connected in series, makes it possible to simultaneously ensure three functions that are difficult to reconcile at this level of performance, namely extreme breaking performance by connection between the two stages of devices, total selectivity between the two stages, and ultra-fast protection of the upper stage in the event of an intermediate fault between the two stages.

Claims

1. Set of electrical protection devices with two levels that are connected in series, the first level including a circuit breaker (1) that is referred to as the first or upstream circuit breaker and the second level including one or more second circuit breakers (8) or downstream circuit breakers, which are connected in parallel with respect to one another, each circuit breaker including, for each of the phases, a switching block through which passes a current line on which two separable contacts and a sensor for measuring the current are placed, means for actuating the contacts manually or by remote control, means for automatically opening the contacts controlled by a trip, said trip being controlled by the aforementioned current sensor, the trip of the second circuit breakers (8) further including what are referred to as instantaneous protection means allowing the trip associated with these second circuit breakers (8) to be actuated when the current reaches what is referred to as an instantaneous trip DIN threshold of these second circuit breakers (8), characterized in that the trip (7) for the upstream circuit breaker (1), instead of including what are referred to as instantaneous protection means, includes, firstly, a first trip chain making it possible to adjust the long-delay trip curve for inverse time and the short-delay trip curve with a no-trip time and, secondly, a second trip chain including an optical sensor (9) that is capable of discerning light between 300 and 450 nm by eliminating visible and infrared light so as to eliminate the light that is characteristic of gas jets emitted by the downstream circuit breakers (8) during a switching operation, and means for simultaneously measuring the current level and the maximum threshold of light emitted at the busbars, this second trip chain being capable of causing the upstream circuit breaker (1) to trip when the current exceeds a predetermined value and the light emitted exceeds a predetermined threshold for emitted light, and in that the downstream circuit breakers (8) have a lower rating than the first circuit breaker (1), and all the trips include means for adjusting the long-delay trip curve for inverse time and the short-delay trip curve with a no-trip time.

2. Set of electrical protection devices according to Claim 1, characterized in that the or each trip (7) includes means for adjusting the long-delay trip curve for inverse time for currents smaller than substantially 10 times the nominal current In and means for adjusting the short-delay trip curve with a no-trip time of 20 ms for currents with a value of between 1.5 and 10 times the nominal current.

3. Set of electrical protection devices according to Claim 1 or 2, characterized in that the circuit breakers (1, 8) are limiting circuit breakers.

4. Set of electrical protection devices according to Claim 3, characterized in that the aforementioned predetermined current value and threshold are 10 times the nominal current In and 8000 lux, respectively.

5. Set of electrical protection devices according to Claim 3 or 4, characterized in that the first limiting circuit breaker (1) has a rating of between 800 and 1000 A, while the second limiting circuit breakers (8) have a rating of between 40 A and 250 A.

6. Set of electrical protection devices according to any one of the preceding claims, characterized in that the first circuit breaker (1) has a rating of 800 A, while the second circuit breaker (8) has a rating of 100 A.

7. Set of electrical protection devices according to any one of the preceding claims, characterized in that the value of the instantaneous trip threshold S of the second circuit breakers (8) is around 11 kArms.

8. Set of electrical protection devices according to any one of the preceding claims, characterized in that the aforementioned upstream circuit breaker (1) includes a pyrotechnic propellant that is intended to allow an ultra-fast trip in the presence of a sparkover fault between phases in the region located between the two stages.

9. Set of electrical protection devices according to any one of the preceding claims, characterized in that the aforementioned optical sensor (9) includes a discriminating optical fibre, said optical fibre including a fibre made of fluoride glass including, at its ends, a treatment that is intended to block waves that are longer than 450 nm.

10. Set of electrical protection devices according to any one of the preceding claims, characterized in that it is used in auxiliary switchboards of ships with a power of higher than 100 KA / 690 V.