DE3132338A1 - METHOD FOR THE IGNITION OF CONTROLLABLE SEMICONDUCTOR VALVES THAT SERVE THE DELETION OF SWITCHING ARM ARCHES OF ELECTRICAL SWITCHING DEVICES - Google Patents

Description

BROWN, BOVERI & C I 2 AKTIENGESELLSCHAFT MANNHEIM. August 13th, 1981

ZPT / P4-Pt / Ht. Mp.no. 615/31

"Method for the ignition of controllable semiconductor valves, the are used to extinguish switching arcs in electrical switching devices "

The invention relates to a method according to the preamble of Claim 1 and a circuit arrangement for performing the method and an electrical switch in which the method and the circuit arrangement is realized.

AC switching devices with a high switching frequency have in particular at higher nominal currents and in heavy-duty operation because of the scarf arcs that occur, a considerable amount Wear on the contact and extinguishing system, de.t their service life reduces and causes maintenance costs. Hybrid switching systems have therefore been used for such areas of application proposed in which the load current commutates after opening the main contacts on a secondary path and there through built-in Semiconductor valves switched off in the zero crossing. An additional separation point in the circuit can be used if necessary formed by a further contact which is in series with the hybrid switching system and always opens without current.

. Eei the use of controllable semiconductor valves in the bypass The mechanical switching point requires these valves to be ignited immediately after the contact piece begins to open, in order to take over the load current and to minimize the effects of the switching arcs that develop to decrease. In previously known arrangements, auxiliary contact systems or external electronic control scarfs are used for this purpose used; both solutions require additional effort and thus increased costs. The reliability of this Auxiliary arrangements are to be made very high demands, since the hybrid switch due to failure of the ignition of the valves the absence of further arc extinguishing devices cannot switch off the load current successfully.

It is therefore the object of the present invention to provide ignition methods to show for controllable semiconductor valves used in the manner described, which are characterized by the smallest possible apparatus Distinguish effort and high reliability, easily integrate into new designs of hybrid switches and, if necessary, with have existing conventional switching devices retrofitted.

This object is achieved according to the invention in that for 'ignition of the at least one semiconductor valve, the electrical and / or optical effect of the arc is used.

When a switching operation occurs - as is known - between the Contact pieces of the contact point of the switching arc. On the one hand, this switching arc generates a voltage drop at least at the base points, which is referred to as the electrical effect of the arc. The electrical effect that is about it also for the dissociation of the air molecules and for their generation of ions, or leads to the generation of the plasma in the arc, should not be considered here. The temperature in Inside an arc is a few thousand ° C; out of here and out For other physical reasons, the result is an optical effect: The arc emits light quanta (light flash)

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The electrical effect is therefore used for the invention the generation of a voltage drop and the optical effect.

A circuit arrangement for carrying out the method is characterized in that the control terminal of the parallel-connected semiconductor valve or the control terminals of paralle.lgeschalteten semiconductor valves between two contact points is connected and that in the control terminal BZV / the control terminals a to influence the control current to-.J ₀ nender ohmic or non-ohmic resistance is inserted.

With this arrangement, the electrical effect of the arc is used. To ignite the semiconductor valve or valves, which then commutate the load current from the contact points.

In order to be able to use the optical effect of the arc, it is necessary to use the semiconductor valve or the semiconductor valve to be arranged in the immediate vicinity of the contact point so that the light-sensitive arc in the event of a switching operation

" ₀ can illuminate semiconductor valve. The semiconductor valve is controlled by the light quanta that the arc emits, and the arc current is commutated from the contact point to the semiconductor valve, which means that the arc is extinguished when the load current passes through zero without any further loading of the contact points.

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There is also the option of the optical and electrical Exploiting the effect of the arc. Then in the control circuit bzv /. the control connection of the controlled semiconductor valve

2Q photosensitive resistor switched by the arc is illuminated and its resistance value is reduced by the irradiation with the arc light, whereby the Arc due to the voltage drop caused by it a current through the resistor and thus through the control

O ₅ connection of the Kalbleitervalve can drive through to control it. It may be useful to select the light-sensitive resistor so that its resistance value follows

Extinction of the switching arc only increases so slowly that the semiconductor valves last longer than for the duration of a load current half-cycle stay ignited. If you also get into the beam path between the arc and the optical or light-sensitive one Component inserts a control disk, which interrupts the beam path and interrupts in a controlled manner, you can add another Achieve improvement of the arrangement and the switching performance.

■ jO With the help of the drawing, in which some exemplary embodiments of the Invention are shown, the invention will be explained and described in more detail.

It shows

Figure 1 to 11 different embodiments of the invention Circuit arrangement.

2Q A first embodiment of the invention is shown in FIGS to 3 shown. The switching device, which is not shown in detail, but which can be designed as a contactor,. Possesses a contact bridge 1 that can be operated in a known manner / the two contact points 6 and 7 one with terminals 5 and 8

Ot ₅ see main current path bridged in the switching device. FIG. 1 shows the switch with open contact points 6 and 7, FIG. 2 shows the switch with closed contact points 6 and 7, a current I shown in broken lines flowing from terminal 5 to terminal 8, and FIG

3Q the contact points 6 and 7 in the open state, with between the 'contact pieces 6a and 7a on the contact bridge 1 (movable contact pieces 6a and 7a) and the fixed contact pieces 6b and 7b an arc 10 and 11 is drawn in each case. In parallel with the contact points 6 and 7, a controllable triac is provided Semiconductor valve 4 is provided, the control connection 3 interposition of a resistor 2 on the contact bridge 1 between “the two contact points 6 and 7

connected. In the embodiment of FIGS. 1 to 3, a double break system is used as a hybrid peeling system used and as mentioned above, the load current flows from the terminal 5 via the contact point 6, the contact bridge 1 7 and the contact point 7 to the connection point 8. The voltage drop at the closed contact point 7 is so small that there is no effective control current from the control terminal 3 to Reference connection 9 of the triac 4 forms. That leaves the Triac 4 de-energized. When the movable contact bridge with the

^ q Contact pieces 6a and 7a mechanically from the fixed contact pieces 6b and 7b is separated in a manner known per se, As mentioned above, the arcs 10 and 11 are drawn, which at the beginning of the switching operation only have a low operating voltage (in of the order of 20 volts). Thus the consortium

_{1 (} - clock bridge 1 compared to terminal 8 has a potential difference that drives a control current via resistor 2 and control connection 3 of triac 4 to reference connection 9. This causes the triac to ignite and take over the load current from the mechanical contact system. This causes the lights to go out.

- ₀ arcs 10 and 11, so that the contact bridge 1 is no longer connected to the main circuit. A renewed ignition of the triac by a control current can therefore not take place and after the load current is interrupted in the zero crossing. backfire is avoided.

FIG. 4 shows a further arrangement in which instead of one

Triacs two anti-parallel, reverse blocking thyristors 12 and 13 are provided. The mode of action is then the same; the control connections of the thyristors 12 and 13 _- are interconnected via additional diodes 14 and 15,

which ensure the function in a manner known per se, and via the jointly used resistor 2 with the contact bridge tied together.

In FIG. 5, the electrical effect of the arc is used in that two in Reverse-conducting thyristors 16 and 17 connected in anti-series are arranged. The control connections 18 and 19 of this both thyristors are directly with each other and across the common Resistor 2 connected to the contact bridge.

Ben arrangements according to Figures 1 to 3, 4 and 5 is common, that, in addition to the described effect when switching off, the formation of bounce arcs is avoided when switching on, because when a potential difference caused by contact bouncing occurs between the contact bridge and the respective reference connection of the respectively acting controllable semiconductor valve the ignition process is triggered in the manner described above and thus the bounce arcs are extinguished. Depending on the position of the switch-on points of the contact points 6 and 7 to one another, the entire switch-on current from the controllable Kalbleitervalventilen be taken over. The resistor 2 is to be interpreted in such a way that when the full Load circuit voltage limits the control current for the valves to the maximum permissible value. This circuit arrangement, with which the method according to the invention can be carried out, can be used with every conventional switching device with a double-break system (for example with every contactor, motor protection switch and the like.) are used, since only "a flexible Connection of small cross-section between the contact bridge 1 and the resistor 2 must be provided with which the control current for the control connections is removed.

The method described can also be used if

Switching arcs of low power electromagnetic relays are to be extinguished. Such a circuit arrangement is shown in the figure. In the main line between the terminals 5 and 8, two normally open contacts 20a and 20b are turned on, which have a Connecting line 20 are connected in series. This ver

. Connection line 20 corresponds in its electrical meaning the contact bridge 1 of Figures 1 to 5. The normally open contact pieces 20a and 20b are controlled by an electromagnetic relay 20c actuated. The ignition of the triac 4, the two make contacts 20 a and 20 b is connected in parallel (one can also say that it is between the terminals 5 and S) in the manner described for the arrangement according to FIG. The arc between one of the two contact points 20a or 20b generates a voltage drop, whereby a potential difference between the control terminal and the in the reference connection of the Trtac, not shown in detail in FIG. 6 causes the triac 4 to be ignited,

In Figure 7 the arrangement is like. Figure 6 modified to the extent that than a normally open contact 21 is additionally actuated by the relay 20c, which contact is designed so that it opens at the contact lags behind the two contact points 20a and 20b »For a single-phase, mains-frequency application, contact 21 for currentless switching at the earliest 10 milliseconds after the hybrid system of the contact points 20a, 20b and the triac 4 Open. This arrangement significantly increases the switching capacity of the relay for alternating current.

The use of the optical effect of the arc is realized in the circuit arrangements Figure 8 to Figure 11 » A single interrupt system is provided in which the main current path between terminals 5 and 8 one has contact lever 41 rotatably mounted in a fulcrum 40, at the free end of which a movable contact piece 42 is attached, which cooperates with a fixed contact piece 43. Parallel to the contact point 42/43 is a light-sensitive one Triac switched. The light-sensitive control electrode must of the triac 22 should be aligned with the contact point 42/43 so that an arc 23 formed there this control electrode of the triac 22 illuminated. If the triac 22 is ignited when the arc occurs according to FIG

• Take over the load current between terminals 5 and 8 and switch it off at the zero crossing. The further flow of load current is prevented because after the switching arc has been extinguished, there is no longer any light for optical ignition.
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The triac 22 can be replaced by two anti-parallel

backwards

switched thyristors 24 and 25, which can also be controlled optically are. The arc 23 radiates its light onto the two thyristors or onto the control electrodes of the two thyristors 24 and 25, which are thereby ignited, take over the load current and after the arc has been extinguished the next Block zero crossing.

The use of the electrical and optical effects at the same time show the arrangements according to Figures 10 and 11. In the arrangement according to Figure 10, it is parallel to the contact point 42/43 a triac 26 is connected, the control terminal 27 of which is connected to the terminal via a light-sensitive resistor 28 connected is. The arc 23 illuminates the light sensitive Kiderstand 28, which reduces its resistance, so that a control current flows via the control connection 27 of the triac to the reference connection 29 of the triac. This ignites it Valve 26 or triac 26 takes over the load current between terminals 5 and 8 and switches it off when it crosses zero. As the resistance value of the photosensitive resistor increases again very quickly after the arc has been extinguished, a control current sufficient to ignite can no longer be used flow.

Figure 11 shows a further variant. Parallel to the contact point 42, 43 is a series circuit of the resistor 28 with two diodes 32 and 33 connected, and further is parallel to the Series connection of the diodes 32, the resistor 28 that of the diode

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' An anti-parallel connection of two thyristors 30 and 31 is connected. The control connection for the thyristor 30 is connected between the diode 32 and the resistor 28 and the control connection for the diode 31 is connected between the Kiderstand 28 and the diode 33 °. Both diodes 32 and 33 relieve the control paths of the thyristors from the reverse voltage stress in a manner known per se. When the arc 23 occurs, the resistance value of the resistor 28 is reduced, as a result of which the two thyristors 30 and 31 are controlled via the two control connections. At zero crossing the arc is extinguished and the control current flowing through the resistor 28 is limited to values below the ignition current, so that the thyristors 30 ″ and 31 go into the blocking state.

The advantage of using the method according to the invention, which at the circuit arrangements of Figures 1 to 11 realized are, is achieved, consists mainly in the fact that the switching contacts are protected by the hybrid switch, wherein the circuit arrangements as such are very simple. the Advantages with the optically effective circuit arrangements (utilization the optical effect of the arc) compared to the method according to FIGS the semiconductor valve takes place optically without an electrical connection to the switching contact. So is The semiconductor device is relieved of the inrush current and it is enough principally a single interruption point for realizing the so-called hybrid arc extinguishing. Will anyway If a double opening is used, which is easily possible, the second contact point can already be produced used at the point of separation. To do this, however, it must lag behind the hybrid contact and thus be switched off without current will. The suppression of bounce arcs during the switch-on process is carried out accordingly by optical ignition in the manner described for the circuit arrangements 1 to 7. Of course, the photosensitive

Components created in the contact area when switching off "Light radiation both directly and indirectly with the interposition exposed to light guides. Of course, these components must be protected from incidence of extraneous light.

The method in which both the electrical and the optical effect of the arc is used (circuit arrangements 10 and 11) is significantly more favorable compared to the circuit arrangement of FIGS. 8 and 9 in terms of the cost of the components Medium frequency range: Since the increase in resistance of the photoresistor occurs only at a limited speed after the arc has been extinguished, the semiconductor valves - in contrast to the application according to FIGS. 8 and 9 - remain conductive during several load current half oscillations. The mechanical ^switching path thus has sufficient time for deionization in any case, so that it is not caused to reignite by the medium-frequency voltage, which rises very steeply when the valves are finally closed. The switching arcs that occur when the system is switched off using the methods implemented in the arrangements according to FIGS. Rather, the switching arcs have a contact-cleaning effect, which is also advantageous.

- ⁵ In the schematic diagrams of Figures 1 to 11, are drive for the movable contact pieces and the switch housing - same have been omitted. Such switching devices are known per se. Furthermore, protective devices for the semiconductor valves against overcurrents and overvoltages are also

and clear presentation has been omitted.

Claims (6)

615/81 claims 1. Process for the ignition of controllable semiconductor valves len, which are connected in parallel to at least one contact point of an alternating current switching device that draws a switching arc during a switching operation to extinguish the switching arc . which _{it is} deleted Yjq ± its zero crossing, characterized in that for the ignition of at least one half terventiles and thus for commutation of the arc current on the semiconductor valve the electrical and / or optical Effect of the arc is exploited. 25th 2. · Circuit arrangement for performing the method na.ch claim 1, with at least two contact points, thereby characterized in that the control connection of the semiconductor valve connected in parallel or the control connections of the parallel connected switched semiconductor valves connected between two contact points and that in the connecting line an ohmic or non-ohmic one serving to influence the control current Resistance is inserted. 3. Circuit arrangement according to claim 2, characterized in that that the control connection on the connecting line formed as a contact bridge of two contact points via a movable electrical line is connected. 4. Circuit arrangement for performing the method according to claim 1, characterized in that the optically ignitable Semiconductor valves are arranged spatially close to the contact point, so that the luminous appearance of the arc Semiconductor valves illuminated. 5. Circuit arrangement according to claim 1, characterized in that the line to the control connection of the semiconductor valve contains a light-sensitive resistor, the spatial Idch is arranged in the vicinity of the contact point and its Resistance value reduced by the luminous appearance of the switching arc. 6. Electrical switching device, in which the method according to claim 1 and the circuit arrangement according to the claims 4 to 5 carried out or applied, characterized in that between the contact point and the light-sensitive Component, d. h «, the photosensitive semiconductor valve or the light-sensitive resistor, one the optical beam path Light beam interruption plate influencing between the switching arc and the light-sensitive component can be inserted in a controlled manner.