DE10004130A1 - Safe operating method for overvoltage protection device with at least two stages, involves controlling spark gap response and ignition time using amplitude of current coupled out on fine element load capacity - Google Patents

Abstract

The method involves coupling out a partial current from the fine protection stage (2) for indirect determination of the energy load on the fine protection element or stage, which causes pre-ionization of the spark gap forming the coarse protection element. The response and ignition time of the spark gap is controlled using the amplitude of the current coupled out depending on the load capacity of the fine protection element. If the load limit of the second stage is reached or exceeded the first stage (1) with the coarse protection element is activated. Independent claims are also included for the following: an overvoltage protection device.

Description

The invention relates to a method for safe operation an at least two-stage surge protection device, which have at least one coarse protection element and one fine protection element ment contains and where the surge protective device is switched between energy source and consumer, and an overvoltage protection device according to the main application 198 38 776.8.

In a variety of applications, especially for Low voltage systems there is a need, on the one hand the lowest possible protection level while remaining the same to ensure high surge current discharge capacity. This is usually due to the technical and physical Boundary conditions of the available overvoltage protection components by combining several, e.g. B. two stage arrester arrangements reached.

A first stage takes over the so-called rough protection, d. H. the derivation of the large surge current. A subordinate second stage, namely the fine protection, can due to the lower discharge capacity only derive the residual disturbances, the latter, however, provides the desired low protection level for sure. This results in a separation of functions between the  Stage for deriving the surge current and the further stage, the ensures the actual level of protection.

Sparks are usually used as arresters of the coarse protection level stretch provided according to the use cases are designed. In particular, lightning current carrying or spark gaps capable of carrying lightning current and extinguishing current Commitment. Such conventional spark gaps have in the However, usually a very high voltage protection level in kilos volt range, which is related to the dielectric strength of the protective devices and systems is too high. That's why one more, d. H. trained the fine protection level mentioned, the e.g. B. comprises a varistor. This fine protection level ensures the desired protection level for the devices and systems. On Decoupling element between the steps ensures that each the arrester elements only so strongly at the discharge of the shock current is involved, as specified by the respective dimensioning.

On the application side, it is desirable that overvoltage protection devices only at the moment of overvoltage limitation and derivation are active and none at all Show effects on the devices and systems to be protected. Also during the actual derivation of the overvoltage the reaction of the protective devices on the system to be protected be as small as possible.

Components with continuous current / voltage characteristics such as metal oxide varistors or suppressor diodes are a thing of the past moved means for fine protection, because due to the impedance Respond and during the derivation process it doesn't open up short-circuit-like condition can occur. Next Such components have an ideal protection characteristic for almost any voltage value.

However, there is a major disadvantage of such components in the relatively low surge current carrying capacity due to the conduction processes in the semiconductor solid also does not significantly improve.  

On spark gaps as coarse protection elements, on the other hand already have a very high surge current carrying capacity pointed out.

A disadvantage of such spark gaps is the occurrence a short-circuit-like state after the response the given discontinuous U / I characteristic. In this Senses is a spark gap with a mechanical one Switch comparable. The existing low impedance causes gently an undesirable short circuit condition, while continuing it is disadvantageous that the protective characteristic curve itself is not constant, but is a function of the steepness of the overvoltage. The The value of the limit voltage for spark gaps can be also influence only with great effort.

With the multi-stage surge protection mentioned above facilities succeed, even if only to a limited extent, Combination of the advantageous properties of coarse protection and Fine protection elements. Such a separation of functions is known for example from DE 38 12 058 A1. There is a decoupling element in the form of an inductance or ohmic resistance available. The known arrangement realizes the impedance ver due to its own impedance ratio of the overall arrangement, d. H. the impedance of the arrester corresponding division of the decoupling element Surge current. This is supposed to have a certain energetic coordi nation of the existing arrester levels. The Ent However, the coupling element must meet a number of requirements len that complicate universal application. Goes on the solution described in DE 38 12 058 A1 assumes that when exceeding one defined for the fine protection branch Current peak value the partial voltages via a varistor and of the impedance mentioned, the height of the spark gap Reach the response voltage so that it ignites.

The solutions according to DE 196 40 997 A1 go in a similar direction, EP 0 186 939 A1 and JP 1-26 8427, in which if a certain voltage value is exceeded, an existing whose trigger device activates the coarse protection spark gap.  

The cited solutions, however, have the disadvantage in common that the activation of the spark gap based on a moment tan voltage or current value or the current change speed occurs.

A relatively short and therefore low-energy disorder can both the same peak and the same increase speed like a high-energy, long-lasting transfer possess tension. However, this occurs in the prior art the problem that even with low-energy disorders, the to be derived by the fine protection element itself could activate the spark gap with night electrode erosion and wear. Also the consumer is burdened by relatively frequent Short circuits due to the behavior of the igniting sparks stretch or power failure. From available studies results in over 90% of the surge events being low in energy are, but have a high voltage peak value, so that new approaches must be sought, such as the undesirable one Activation of the coarse protection elements can be avoided.

It was recognized that the factors voltage and current or di / dt not a measure of the energetic load of the fine protection represent elements. Rather, it is necessary here, according to the relationship W = ∫ uidt the duration of the action as essential parameters to consider.

From the above it is therefore in continuing education the main patent application mentioned at the beginning Invention, a method for safely operating a mind Very two-stage surge protection device and one Surge protection device to specify which at least one Coarse protection element and a fine protection element contains and where the surge protection device between the energy source and Consumer is switched. According to the task actually Energy converted in the fine protection element is recorded and used for control the surge protection device can be used so that is excluded that short, low-energy disturbances, the  a high peak value or a high increase di after dt own, already increasing the spark gap activate.

The object of the invention is achieved with a Ver drive as it is defined with claim 1, and with an overvoltage protection device according to the features of claim 4, wherein the sub-claims at least purpose represent moderate configurations and further training.

In a two-stage overvoltage protection device for low-voltage systems, the first protection stage having a high current discharge capacity and the second protection stage having the lowest possible voltage protection level, and both stages being provided as parallel line branches between supply lines that connect an energy source to a consumer, the method in the second Protection level existing, actually implemented energetic load by evaluating the ∫ i according to dt, nach u according to dt and / or the power conversion according to ∫ uidt, ∫ u ² dt or ∫ i ² dt and when reaching or exceeding the load limits of the second level in an the first level of protection is activated in a known manner.

According to the invention is used to determine the actual energy table load of the fine protection element or the fine protection stage decoupled a partial stream from this stage. This If necessary, the rated partial flow will be a special one Spark gap supplied to cause a pre-ionization there ken. About the size, but also the type of power extraction and the amount of ions formed can affect the response and the Time of ignition of the coarse protection spark gap in depend of the resilience of the fine protection element then in in a surprisingly simple way.

Due to the adjustability of the pre-ionizing auxiliary arc the coarse protection spark gap and the structural design the spark gap ensures that the one activated first  Fine protection element within the limits of its resilience Voltage peaks and currents dissipate without the main sparks route is ignited, but on the other hand it is guaranteed that the fine protection element within the scope of its application parameters can be operated trouble-free.

By choosing low values of the extracted partial flow and a correspondingly given amount of ionization charge Qz The main spark gap of the coarse protection element is the mentioned undesired ignition in the case of short faults, even steep slopes and slew rate avoided.

The spark gap of the coarse protection element has a part spark gap low response voltage, which is the partial current is fed from the fine protection level. The ignited Partial spark gap and the arc that arises there sets Charge carriers free, which is the main spark or another Partial spark gap of the coarse protection element, pre-ionizing it, is fed.

The first partial spark gap forms together with the current coupling from the branch of the fine protection element quasi a measurement device for the energetic load. The as abge current flow to be considered then ionizes over an auxiliary arc that occurs in the first partial spark gap trains the arc space of the second or main spark route.

After igniting the main spark gap, it takes over fully constantly the current and relieves the rest of the arrangement, d. H. the Fine protection element, which changes to the OFF state. The Relief is determined by the adjustable impedance ratio nisse and / or about the specific dimensioning of the sparks route, which according to the arrangement is preferred as a three-electrode Spark gap is formed.

The quantity of the second or main spark gap supplied Load carriers per time are proportional to that in the fine protection element  implemented charge Q = i. t and represents the desired one Image of the energetic load of the fine protection element in the The meaning of an indicator function.

The partial flow which is derived from the fine protection branch can be set via linear or nonlinear impedances and be specified, with time as a further influencing variable the current flow duration is given, which is the exposure time of the corresponds to the current fault.

The amounts of ionization charge Qz required to ignite the Coarse protection spark gaps are determined by their geometry parameters fixed.

If the measuring current is selected to be low, this results due to the relationship Qz = constant, since this is a construct tion-specific size is, a longer current flow time until the charge Qz required for ignition is reached. This is it is possible to ignite the spark gap by in duration suppress short glitches. Such impulses Low-level faults are caused by the varistor or a similar fine protection element derived.

In contrast, the current flows through the pre-ionization spark gap relatively long, as is the case with energy severe disorder, e.g. B. flash is the case, then the ignites Spark gap when the necessary amount of charge Qz is introduced has been.

By choosing the maximum ionization current, the adjustable time, given a fixed amount of primer charge Qz window for the activation of the main spark gap give.

Specifically, there is the surge protection device, the Grob contains protective and fine protection elements, from a coarse protection element in the form of a z. B. encapsulated three-electrode spark gap,  the electrodes having two spark gaps with under form different ignition voltages.

The first of the two spark gaps is with one through the Fine protection element flowing current or abge from it branched partial flow. The first spark gap points a relatively low ignition voltage, which means that it can also be used the early ignition of this first spark gap as ions Dimension and image for the energetic load of the fine protection elements releases and this of the second spark gaps leads. This second spark gap has an essential one Lich higher response or ignition voltage, so depending on the ratio of the partial arcs that develop Spark gaps a timed and controlled ignition of these can be done.

To set the partial current between the Feinschutzele element with a given impedance Z ₃ and the electrode of the first spark gap, a first impedance Z _{1 is} provided, a second impedance Z _{2 being connected} to ground at the node between the first impedance Z ₁ and the fine protection element . The ignition behavior can now be controlled by setting the impedance ratios.

In one embodiment, the second impedance can be designed as a transformer, to whose primary circuit the first impedance Z _{1 is} connected and whose secondary circuit determines the value of the second impedance Z ₂ .

The three-electrode spark gap is designed so that the Spacing of the electrodes and / or their diameter of Arc chambers to form different partial arcs the partial spark gaps are in a predetermined ratio, which is essentially 1:10.

With a choice of the impedance Z ₂ with a value towards 0, the first impedance Z _{1 should be} approximately ten times the impedance Z _{3 of} the fine protection element.

In the case when the second impedance Z ₂ assumes a very large value and the first impedance Z ₁ goes towards 0, control takes place solely via the design of the partial spark gaps, here the second partial spark gap should have a response voltage that is substantially larger than the response voltage of the first spark gap.

As stated, the coarse protection element should have at least two Partial spark gaps have a first auxiliary spark stretch that after their ignition by means of the ionized gases of the pre-arc produces charge carriers that are in the Main spark gap are introduced, so that the latter before is ionized.

The ignitable via the pre-ionization of the auxiliary spark gap Main spark gap must be able to handle the entire surge current to lead and derive.

Such behavior can be determined by different elec reach trodenabstanden, so that a favorable ratio of Partial arcs with optimal control effect for the time continued ignition of the partial spark gaps is given.

Especially with spark gap arrangements with trained Arc chambers can exhibit similar behavior through a Achieve variation in chamber diameter.

The invention is illustrated below with the aid of an embodiment game and explained with the help of figures become.

Here show:

Figure 1 shows a basic circuit variant of an overvoltage protection device with three-electrode spark gap.

Figure 2 is a schematic diagram of a control solely by the formation of the spark gap and impedance Z ₂ to Z ∞ at ₁ in the milliohm range.

Figure 3 is a control of the partial arcs about the adjustment of the impedance ratios, as well as a variation of the impedance Z ₂ using a transformer or transformer.

Fig. 4 is a coarse protection element in the form of a three-electrode spark gap and

Fig. 5 is a rough protective element in the form of arc chutes with varying chamber diameter D ₁ and D _2.

The basic circuit variant shown in FIG. 1 is based on a stepped surge protection device with a coarse protection element 1 in the manner of a three-electrode spark gap and a fine protection element 2 connected in parallel. The fine protection element 2 can be a varistor, an ohmic resistor, a suppressor diode or a similar known element, as is shown symbolically.

Via an impedance Z ₁ (reference numeral 3 ) in the form of a resistance or an inductance or else via a varistor, the three-electrode spark gap 1 can be supplied as a coarse protection element, a pre-ionization current. The impedance Z ₁ is connected to a node of a series connection of fine protection element 2 with a second impedance Z ₂ (reference sign 4 ). The overvoltage protection device is used in a known manner in a low-voltage system, the two stages being designed as parallel line branches between supply lines which connect an energy source and a consumer to one another.

The impedance Z ₂ can be formed as an ohmic resistance, but also as a transformer or transformer or pure inductance.

In the example shown in FIG. 2, it is assumed that the impedance Z _{2 is} very high, whereas Z _{1 is} in the milliohm range. In this case, the partial arcs of the three-electrode spark gap are controlled solely via their geometrical design, the pickup voltage e ₁ being chosen to be significantly smaller than the pickup voltage e ₂ .

In an impedance control according to Fig. 3 in the case of a value Z ₂ approaches 0, z. B. lying in the mΩ range, Z _{1 selected} so that it assumes about ten times the value of the impedance Z _{3 of} the protective element.

The embodiment shown in the lower part of FIG. 3 represents a variation of the second impedance Z ₂ , which comprises a transformer 5 . The first impedance Z _{1 is} connected in the primary circuit of the transformer 5 , the secondary circuit of the transformer 5 determining the value of the second impedance Z ₂ .

In the three-electrode spark gap according to Fig. 4, two partial spark gap to be formed FS1 and FS2, wherein the spacing of the electrodes for the partial spark gap FS1, namely 11, Wesent Lich is smaller than the distance 12 between the electrodes of the partial spark gap FS2. The first impedance Z ₁ leads to the second electrode of the first spark gap FS1. In the event of an interference pulse, a current initially flows through the fine protection element 2 with a resulting partial current via the impedance Z ₁ to the electrode of the partial spark gap FS1. Due to a correspondingly low response or ignition voltage, this first spark gap FS1 now ignites and releases charge carriers which are fed to the second spark gap FS2 for their pre-ionization.

The ratio of the electrode spacings 11 and 12 is about 1:10 before given, so that there is a corresponding ratio of the partial arcs with optimized control effect and the desired time-delayed ignition of the partial spark gaps.

The ionized gases generated in the partial spark gap FS1 or the resulting pre-arc produces charge carriers which represent a measure of the energetic load on the fine protection element 2 . After igniting the main spark, which takes place via the pre-ionization, the three-electrode spark gap takes over the entire surge current, so that the fine protection element 2 is protected in the event of correspondingly large faults. The required amounts of ionization charge Qz for igniting the spark gaps are determined by the geometry parameters, so that there are corresponding possibilities for energetic coordination of the effects or the response of the fine protection element and the coarse protection element.

In the variant according to FIG. 5, a spark gap arrangement with arc chambers is assumed, the setting of the response behavior of the partial spark gaps being given by a variation in the chamber diameter D ₁ and D ₂ . In the example according to FIG. 5, it is assumed that Z ₂ assumes a very large value, so that there is a control effect, as explained for FIG. 2.

The spark gap FS1 forms, together with the impedance Z ₁ or the ratio of the impedances Z ₁ , Z ₂ and the properties of the fine protection element 2, a measuring means, the measuring current branched off from the current path of the fine protection element 2 showing an auxiliary arc in the partial spark gap FS2, which again the pre-ionized arc space of the partial spark gap FS2. The charge carrier flow from the partial spark gap FS1 into the space of the partial spark gap FS2 continues until the spark gap ignites. After this complete ignition of FS2, it takes over the interference current and relieves the fine protection element in the desired manner so that it is protected. The degree of relief, as described, is determined by the impedance conditions in the partial circles and can be controlled via their dimensioning.

All in all, the present invention succeeds in Method for operating a surge protection device and to specify such a facility that an optimal Utilization of coarse protection and fine protection elements made possible by an indirect determination of the energetic Loading of the fine protection element or the fine protection level takes place, so that only then a wear associated Triggering the coarse protection spark gap is initiated when exceeding the protection parameters of the fine protection element threatens.

Claims (9)

1. A method for the safe operation of an at least two-stage surge protection device which contains at least one coarse protection element and a fine protection element and wherein the surge protection device is connected between the energy source and the consumer, characterized in that a partial flow from the for indirect determination of the energetic load of the fine protection element or the fine protection stage Fine protection stage is decoupled, which causes a Vorioni sation of the coarse protection element designed as a spark gap, the speak to the size of the current decoupling and the timing of the ignition of the spark gap depending on the load capacity of the fine protection element is controllable and / or that in the downstream or second Protection level existing, actually implemented energetic load by evaluating the ∫ i according to dt, ∫ u according to dt and / or the power turnover according to ∫ uidt, ∫ u ² dt or ∫ i ² dt t and when the load limits of the second stage are reached or exceeded, the first protection stage with coarse protection element is activated in a manner known per se. 2. The method according to claim 1, characterized in that by specifying low values of the extracted partial stream and given ionization charge quantity Qz of the spark gap of the Coarse protection element an undesired ignition of the same short glitches, also steep slopes and ascent speed is prevented. 3. The method according to claim 1 or 2, characterized in that the spark gap of the coarse protection element is a partial spark gap has lower response voltage to which the partial current flows, the ignited partial spark gap charge carrier  which releases a main spark gap of the coarse protection elements for pre-ionization. 4. Overvoltage protection device which contains at least one coarse protection element and one fine protection element and wherein the overvoltage protection device is connected between the energy source and the consumer, characterized in that
the coarse protection element is a three-electrode spark gap, the electrodes forming two spark gaps with different ignition voltages,
the first of the two spark gaps is acted upon by a current flowing through or derived from the fine protection element and this first spark gap has a low ignition voltage, whereby ions release the ignition as a measure and image for the energetic load of the fine protection element and the second of the spark gaps with a higher one Response voltage are supplied, so that depending on the ratio of the partial arcs forming, a timed and controlled ignition of the partial spark gaps takes place. 5. Overvoltage protection device according to claim 4, characterized in that a first impedance Z _{1 is} provided between the fine protection element with a given impedance Z ₃ and the electrode of the first spark gap, with a second at the node between the first impedance Z ₁ and the electrode of the first spark gap Impedance Z _{2 is} switched to ground and the control of the Zündver ratio is adjustable via the impedance ratio. 6. Overvoltage protection device according to claim 5, characterized in that the second impedance is designed as a transformer, to the primary circuit of which the first impedance Z _{1 is} connected and whose secondary circuit determines the value of the second impedance Z ₂ . 7. Overvoltage protection device according to one of claims 4 until 6, characterized in that the distances between the electrodes and / or the diameter of Arc chambers of the spark gap differed for formation partial arcs of the partial spark gaps in a pre given ratio, which is essentially 1:10 is. 8. Overvoltage protection device according to claim 5, characterized in that in the case when the impedance Z ₂ goes to 0, the impedance Z _{1 is} approximately ten times the value of the impedance Z ₃ . 9. Overvoltage protection device according to claim 5, characterized in that with a very large, going to infinite impedance Z ₂ and an impedance Z ₁ to 0 going the second partial spark gap has a much larger response or ignition voltage than the first partial spark gap.