HU183117B - Fuse with microdetonator - Google Patents

Abstract

The present invention relates to an insertion insert which, due to its novel operating mechanism, is better able to meet the increasing demands of insurers than known solutions. The fuse according to the invention has one or more circuit-breaker elements, e.g. with a main circuit and auxiliary circuit breaker element, and the invention is that the breaker element (b) or, in the case of multiple circuit elements, at least one explosive (microdetonator) of the main circuit breaker (b) is provided, the explosive energy of which (Er ) Emin V Er <n.Emax, where Emin is the smallest amount of energy providing at least one cross-sectional breakage of the breaker element, Emax is the smallest amount of energy suitable for damaging the enclosed enclosure and n is the safety factor (eg 0.1). bail

Description

FIELD OF THE INVENTION The present invention relates to a fuse, and more particularly to a fuse, which, by virtue of its novel mechanism of operation, is able to better meet the ever-increasing demands on fuses, such as, e.g. super-fast operation, limiting overvoltage in a way that does not imply additional short-circuit current, reliable and safe operation.

An important field of application of the present invention is the protection of high current semiconductor devices, and therefore, the present invention will be described in detail in connection with the use of a main electrode and auxiliary electrode.

However, the invention is not limited to this field of application. It refers to a novel interruption mechanism that can be useful in performing various protection tasks under different load conditions, regardless of how additional conditions are provided, e.g. surge protection, arcing, etc.

The present invention is based on the discovery that, instead of or in addition to the basic operating characteristic of known fuse-type fuses (interruption of material melting at a certain section of the current conductor, interruption of the main energy flow must be solved by mechanically breaking the conductor) triggered by explosive energy of the selected magnitude; in the fuse insert, the interruption at the (main) electrode is thus caused by the explosive medium (the so-called microdetonator) disposed on the electrode (s) exploding when the conductor temperature in the vicinity of the microdetonator exceeds the rated fuse reaction temperature interrupt must occur). Thus, while in the case of known fusible fuses, the interruption of the conductor is caused by a change in the state of heat, according to the invention, the interruption of the conductor (at least the main current) reaction, much faster. This is especially true in the special case of an explosion, which is described in the literature as detonation, where the explosion does not spread by burning, but by an explosion pressure wave. It is known that the propagation of a pressure wave is a much faster process than heat conduction, and the heat of reaction is released in a much shorter time in detonation than in a conventional explosion, therefore its destructive effect may be greater but more concentrated and thus more localized in energy generation and control. and the right amount of energy. The state of the art already provides many opportunities for detonation conditions, and the choice of a suitable explosive can be varied. Especially suitable for inducing detonation according to the invention are e.g. of the explosives is the well-known lead diazide (or mixture thereof) or the less widely used silver carbide (or mixture thereof), the latter of which provides energy for the decomposition of the carbon triple bond. It follows from the foregoing that the favorable operating speed of the interruption mechanism of the present invention can be substantially determined even if detonation mechanical destruction is used to interrupt the current conductor carrying the main power current; for the auxiliary electrode that may be used, the interruption mechanism may still be conventional melting.

Accordingly, the fuse according to the invention has one or more circuit breakers forming a closed housing conductor (s), e.g. main circuit and auxiliary circuit breaker, and the invention is characterized in that the breaker element (b) or, in the case of several breaker elements, has at least one - preferably the main circuit breaker element (b) - having an explosive medium (microdetonator) _r )

Emin <E _r <nE _max , where E _m j _{n is} the minimum amount of energy to provide complete disruption of the circuit breaker in at least one cross section,

This _{max is} ^the minimum amount of energy that can be used to damage ^the enclosure and the safety factor (eg 0.1).

Preferably, the nominal ignition temperature of the medium forming the microdetonator is equal to the nominal reaction temperature of the fuse. However, it is preferable to use an embodiment where the ignition temperature of the medium forming the microdetonator is greater than the nominal reaction temperature of the fuse, and an ignition element known per se on the microdetonator is provided, the ignition temperature of which is higher than A known ignition element is provided having a ignition temperature equal to the rated reaction temperature of the fuse. Such an ignition element may be e.g. a spark generating ignition element. One advantage of this embodiment is that the range of variation is optimized to optimally match the different properties of the explosive medium, since we are not bound by the choice of medium to match the two reference temperatures. Another advantage is that the explosive medium itself, where the initiation of the chemical process results in the rapid release of all energy, cannot directly initiate an explosion in the operating temperature range, including its ambient temperature environment, and thus the inevitable tolerance field of the explosive medium for the mechanism, only the trigger temperature of the firing element is reliably controlled, which may be easier, since this element is the only delicate hysteria, while handling more features than the detonator is delicate. Thus, in this embodiment, a high degree of stability of the properties and a higher degree of thermal insensitivity to the environment can be ensured.

The breaker element formed by the microdetonator can also be implemented in many ways. The conductor may be a metal foil, a conductive layer applied to an insulating support, e.g. coal or metal layer, metal wire, etc. In any of these designs, the conductor can be stretched between supports (which increases the destructive ability), or it can be wound on an insulator holder, which gives it greater freedom in terms of other material geometry.

The closed housing or a portion thereof may be filled with an extinguishing agent, e.g. quartz sand, and the breaking element

-2183 117 can be embedded in or passed through this medium.

The shape and arrangement of the microdetonator can vary. It is possible to form a solid pastille, which is glued to the conductor or, in its vicinity, to the insulating body holding the conductor, with a clamp, etc. strengthened. It can be filled in powder form into a holder (bag, etc.) and affixed in a similar manner. It can be inserted into the cross section of the conductor. The circuit breaker portion of the current conductor may be made of tubular conductor material and the detonator disposed within this tube, thereby maximizing the approximation of the temperature of the detonator ignition and the conductor temperature to be monitored. In the metal tube, e.g. a nest enclosed by two cross-sectional constrictions and arranged therein, either in powder form, embedded in an amorphous binder structure, or as a lozenge.

To illustrate the invention in more detail, security systems operating with such a mechanism are referred to as pDR fuses.

The field of application of high current semiconductor devices in modern equipment is expanding day by day. The protection of these devices or equipment sets special requirements for the protection devices, which are often not easy to meet.

The failure of semiconductor diodes and thyristors is mainly caused by short-circuit or short-term short-circuit short-circuit pulses, which are generated in the load circuit for various reasons. Protection against them is important both for operational security and for the relatively high commercial cost of the device to be protected. The most common, cheapest way to protect them is to use a fuse. (Other devices are also used, such as quick switches, etc. These are much more complicated and costly.) In this field of application, fast-acting fuses are required, and their production is quite difficult.

The problems are not just technological. The principle applied to the operation of fuse fuses places significant limitations on certain characteristics. It is worth recalling some basic things from the theoretical description of insurers to determine what you can expect and what your options are for a particular construction.

The principle of the fuse is quite simple: The thermal effect of a current in a conductor rapidly heats the conductor to melt, when it is sufficiently energized, and then the resulting electric arc burns, evaporates, or evaporates the conductor. its part used as insurance. thus the operating time of the insurer (the time from the beginning of the short circuit to the complete interruption of the circuit):

^ operating ⁼ stealing ^ ”

Mathematically, both members of the sum can be approximated quite well. In practice, the melting time is reduced by replacing a portion of the melting fiber with a readily meltable metal.

The operating time plays a role in determining the peak value of the short-circuit current generated in a given short circuit. In fact, fuses usually cut off current flowing through the circuit earlier than it could develop to its maximum value at load inductance. During operation, the Joule heat generated by the amount of electric charge traveling through the circuit exerts its destructive effect, which is a characteristic of the fuse. proportional to the effect, lm

Oh = fi ² 0) dt,

O secondly due to the current being electrodynamic effect dangerous high value of the prospective current (several kA _x 10 '). Because in practice we almost always break an inductive circuit, the change in current causes a voltage on the inductor, which appears as a consumer overvoltage:

if we assume that the current surge is straight in the first approximation. ΔΙ is the sum of the peaks of the current function relative to 0, and Δί is the difference between the peak time and the total interrupt time. (So in practice At ^ tf _ve ) _and i-) In borderline case 0 interrupts! time would create infinite tension.

An important conclusion can be drawn from the above. If we want to keep the fuse surge within acceptable limits, we can only cut a small amount of power in a shorter period of time. For example, if we can reduce the interrupt time to one-tenth of the time (spin time), the start-up rate can only be about one-tenth. The value of this starting current is determined by the melting time, that is, the magnitude of the current rising until the start of the arc. It follows that the melting time should also be significantly reduced, but this is limited by the value of the thermal time constants resulting from the design of the fuse. However, it will be seen that the above requirements can be met by a new system fuse device, the pDR system fuse.

The operating principle of the pDR fuse is very simple (see Figure 9):

In the center of the metal foil 91 (aluminum) is the yarn-like microdetonator 92 (current is limited by a series resistor 93). The current passing through the metal film 91 heats the metal film 91, which heats the μ-detonator to a flash point. It then establishes microdetonation, thus cutting off the foil in its vicinity and breaking the circuit. Often, and most importantly, the micronutrient composition of the microdetonator is exemplified. It should be a substance that is very small but strong! ralized to produce a strong (micro) explosion (in a few mm environments). Thus, it should be a material which has a very high explosion rate in the open air, is sufficiently stable under thermal load and has a well-defined ignition temperature.

The metal film 91 heats up to the ignition of the microdetonator (hereinafter; / (DR)) (e.g., 200 ° C), which is close to the melting temperature of the fast fuses, so that their heating time would be the same if the time constants were the same. much smaller (see below):

Warm up! time:

_t ^ _t_

Γ T c G

T (t) = v _k + Far (le) + T ₀ e, where T = - „- and

Q.ö

-3183 117

Τ - the thermal time constant

G - weight of the filament a - heat transfer coefficient S - surface of the filament and c - specific heat of the filament '

Due to the construction, the surface is 20-50 times larger than the conventional one, so the operating time can be similarly shortened. This is all the more so because the interruption is dominated by warm-up time, as the interruption time is very short. (For example, assuming an explosion speed of 5000 ~ for a 10 cm wide tape, t _r = ~ = = 4 · 10 ^-4 = 2 · 10 ^s sec, i.e. 20 v 5.1CP for 5 microseconds!)

This short interruption time can be increased by an auxiliary thread to adjust the appropriate overvoltage level.

At one point of the metallic guide, the gD process begins. High-velocity gas molecules colliding with the metal tape "shear" the tape. This is continued until the conductor cross-sectional reduction is such that the melting speed produced by the current density increase is in the order of the burst velocity. At this point, the arc and μϋ process occur simultaneously on a short section (v) of the tape. At this temperature, the molecules of the detonator are very low in the ionic state, so they behave mainly as insulators (SAHA equation) and, on the other hand, have high motion energy, so the potential peak at the edges of the tape does not affect their path. Detonator molecules colliding with arc atoms transfer some of their kinetic energy to the atoms of the arc, so they are also removed by. Potential space. Thus, the area around the arc will be free of charge carriers, since atmospheric air with insulating effect will flow there. All this takes place under a few ps, in a practically feasible construct, almost imperceptibly from the outside.

It has already been mentioned that the construction of the pDR type fuse can be varied. Hereinafter, some preferred embodiments are illustrated by means of the drawings.

Figure 1 is a side view, partly in section, of an exemplary embodiment. Figure 2 is a front and side view of the foil holder sheet of Figure 1. Figure 3 shows an extension of the embodiment according to the components (not explained separately, for reference, the functional symbols of some functional elements are shown). Figure 4 is a side view, partly in section, of this type of embodiment with functional characterization.

Figures 5, 6, 7, 8 and 10 show examples of a preferred configuration and fastening of a type of DR fuse.

Figure 9 illustrates the operation of the invention.

Fig. 1 illustrates the fuse housing 4 enclosed by the cover plates 3 by means of screws 2 having the same shape as the conventional one and having blade contacts 1 therethrough. The conductive connection between the two blade contacts 1 is provided within the housing by the two circuit breaker elements of the insert, namely the auxiliary melting circuit 9 and the main circuit breaker type pDR formed by a foil support plate 5 wound on the spiral support block. Reliable contact of the auxiliary melt 9 is provided by a compression spring 8, and the insert 6 dampens against the inner wall of the fuse housing 4.

4 shows that the main electrode 45 embedded in quartz sand 41 is powered by a conductor 46 which bridges microdetonator 42 installed in one of its cross-sections, which breaks very rapidly as a result of the explosion, causing further bursting of the compression wave along the main electrode 45. the specified condition (at least one complete break along at least one cross-section) is created as soon as the thread is interrupted. The auxiliary melting device 44 and the surge suppression device 43 may be designed independently of the mDR mechanism.

Figure 5 shows that the conductors 54 introduced into the sealed housing are interconnected by the conductive foil 53, the clips 51 being flush with a ceramic insert 52 and having a microdetonator 55 thereon.

Figure 6 shows that the medium 61 of the microdetonator is positioned in the curvature of the breaker and is protected against splashing when stored in an insulating bag or other suitable design.

Figure 7 shows that a portion of the conductive circuit breaker element is provided with a microdetonator 73 in a housing 72 enclosed by a thin-walled tube 71 and its two cross-sectional constrictions.

A further variation of this is shown in Fig. 8, where the current I passes through a reduced cross-section around the microdetonator 81, which must be dimensioned to withstand the current I.

Thus, when designing the functional characteristics of pDR type fuses, the material characteristics and the geometrical characteristics determine the functional characteristics, which can be performed by one of ordinary skill in the art, using computer equipment as necessary. The trigger temperature of the fuse is essentially determined by the ignition temperature of the microdetonator or, in the case of indirect ignition, the flash point of the ignition element. In the former case, the chemical composition of the medium can be influenced, while in the latter case the possibility of variation is multidirectional. For a compound medium, the component with the lowest flash point is usually the one which determines the flash point. In practice, this value is e.g. May vary between 250 ° C and 400 ° C.

The basic operating time is defined as the time from the reaching of the critical temperature to the complete non-conductivity of the main circuit element. This is a stochastic value, theoretically converges to zero, its upper limit is influenced by geometric dimensions and the microdetonator burst speed. The analysis of this is based on the assumption that the explosion occurs at a single point, which is the geometric starting point for the propagation of the explosion. In practice, only faster operation is conceivable. For example, assuming a Gaussian probability distribution, we can determine the most probable values of the basic operating time and, by locating the spray field correctly, select the values of the geometric and material quality factors that influence the coefficient of time function.

For the reliable operation, the insurer must also meet safety factors. The construction must also have some spare capacity due to manufacturing faults: in the event of malfunctioning, it must fulfill its basic function of interrupting the circuit, possibly in a way other than normal operating conditions.

183,117

On the other hand, even minimal interference with conventional technology may justify combining conventional fuses with the pD process.

In fact, intervention in this way also offers significant benefits in the following ways:

reaches the reaction temperature of μϋ with the thermal time constant of the main conductor. At this time, no current will flow in this circuit, since on the one hand, the recombinant current on the auxiliary melting fiber initially generates only a low voltage, thus creating a low voltage between the interrupted electrodes and, on the other hand, no free charge carriers. Thus, the recombined current will be interrupted by the auxiliary melting fiber, which has a significantly lower λ ² t characteristic, thus significantly reducing the operating time.

The auxiliary electrode is a surge suppressor filament arranged in a conventional manner. This fuse also fulfills the safety requirements and acts as a standard fuse in the event of a fault.

Advantages of the pDR security system:

In view of the above, the pDR securing system of the present invention has several significant advantages:

- arbitrarily short operating time without overvoltage - low loss compared to major dissipation of conventional types - can be manufactured with geometric dimensions smaller in the current of the NCI, thus resulting in significant material savings - fast operation in direct current circuits - no need for dynamic application whereas the permissible current peak is only 100 A, which means that indirectly significant costs can be saved, - its production is simple, it does not require any special equipment, - it has a good working capacity even above 200 A, which is a problem traditionally unresolved,

- its design can be adapted to conventional sockets; - due to its properties, it can be not only an import substitute but also a sought-after export item; - the time constant can be varied due to its design by suitable choice of effective surface and effective conductor weight.

It has already been mentioned that the inventive idea may, in many respects, devise embodiments differing from the embodiments disclosed so far, provided that the necessary and sufficient conditions for the effect of the invention to be fulfilled are fulfilled, and the essential characteristics required for this are realized. In order to illustrate the versatile possibilities of adaptation and development, Figure 10 is a sectional view of an improved solution. The sections 102 and 103 of the current conductor to be interrupted are fitted in the housing 101 of the fuse block; their opposing ends are formed by discs 106 and 107, each made of conductive material, which are separated in the center by a dielectric medium 108 in a spherical shape. The insulating medium 108 may be a body made of insulating material, air, etc. In the outer circumferential section of the discs 106 and 107, they are connected by an annular current conducting strip 104, e.g. extruded metal powder, liquid mercury in a hose, exceptionally a gas-tight enclosure, a gaseous conductor, or any other properly arranged conductive medium. An explosive body 105, also annular, inserted between the two discs 106 and 107, is fitted to the inner peripheral surface of the conductive strip 104. The contact pressure between the two discs 106 and 107 and the conductive strip 104 between them can be provided in a manner conventional in the art; with spring clamp, fastener, compression, etc.

Such a design of the conductive band 104 allows for a significant increase in the conductive cross section of the current conducting section to be interrupted without deterioration of the destructive conditions, and even the proper choice of material and shape of the conductive band 104 can even significantly improve the interruption conditions.

Claims (13)

Patent claims A fast-acting fuse, preferably for use in fuses for the protection of high current semiconductor devices, with one or more circuit breakers forming a closed housing conductor (s), e.g. a main circuit and auxiliary circuit breaker, characterized in that an explosive medium (hereinafter referred to as a "no microdetonator" (42,92)) is disposed on the (at least one) circuit breaker having an explosion energy (E _r ) Emin <E _r <nE _max where E _m j _{n is} the minimum amount of energy that will provide complete breaking of the circuit breaker along at least one cross section, E _{max is} the smallest amount of energy that can be used to damage a closed housing, n is a safety factor (eg 0.1). (Priority: 04.01.1980) 2. The f. An embodiment of a fuse according to claim 1, characterized in that the circuit breaker with the microdetonator (42,92) is the main circuit breaker. (Priority 04.04.1980) Embodiment of the fuse according to claim 1 or 2, characterized in that the nominal ignition temperature of the medium forming the microdetonator (42,92) is equal to the nominal reaction temperature of the fuse. (Priority 04.04.1980) An embodiment of a fuse according to claim 1 or 2, characterized in that the nominal ignition temperature of the medium forming the microdetonator (42,92) exceeds the fuse rating: ·; reaction temperature and is known per se on or in the microdetonator (42.92), e.g. a spark - ignition element is arranged having a flash point equal to the rated reaction temperature of the fuse. (Priority: 9/6/1980) 5. An embodiment of a fuse insert according to any one of claims 1 to 3, characterized in that the interrupting element formed by the microdetonator (82) is a metal foil (91). (Priority 04.04.1980) 6. The fuse insert according to any one of claims 1 to 5, characterized in that the breaker element formed with the microdetonator (42,92) is insulating 183 11 a guide layer applied to a support, e.g. carbon or metal layer. (Priority: 01.04.1980) 7. Embodiment of a fuse insert according to any one of claims 1 to 3, characterized in that the interrupting element provided with a microdetonator (42,92) is a metal wire. 5 (Priority: 01.04.1980) 8. Figures 1-4. An embodiment of a fuse insert according to any one of claims 1 to 5, characterized in that the discontinuous member is formed by a tube (71) made of conductive material and the medium forming the microdetonator (73) is disposed in a tube wall (72) formed by the tube (71). narrowing cross section. (Priority: June 9, 1980) 9. Figures 1-8. An embodiment of a fuse insert according to any one of claims 1 to 3, characterized in that the fuse housing 15 (4) or part thereof is provided with a curling medium, e.g. it is filled with quartz sand (41) and the breaker element (s) is passed through the medium. (Priority: 04.01.1980) Embodiment 20 according to claim 5, characterized in that it comprises a spiral holding block (7) on which a foil support plate (5) made of a heat-resistant material is wound and the metal foil (91) is arranged on the plate (5). or crafted. (Priority: 04.04.1980) 25 An embodiment of a fuse insert according to any one of claims 1 to 10, characterized in that the medium (one component) of the microdetonator (42,92) is silver carbide. (Priority: 9/6/1980) An embodiment of a fuse insert according to any one of claims 1 to 10, characterized in that the medium (one component) of the microdetonator (42,92) is lead diazide. (Priority: 9/6/1980) An embodiment of a fuse insert according to any one of claims 1-4, 11 or 12, characterized in that the opposite ends of the matching sections (102 and 103) of the current conductor to be interrupted are each - made of conductive material - discs (106 and 107) separated from each other in the middle by a rotating body (108) and interconnected by an annular conductive strip (104) in the outer circumference of the discs (106 and 107), the inner peripheral surface of which has been inserted between the two discs (106 and 107) - also annular - explosive body (105). (Priority: 11/11/1980)