DE1229162B - Device for switching off alternating currents without sparking - Google Patents

Description

FEDERAL REPUBLIC OF GERMANY

GERMAN

PATENT OFFICE

EDITORIAL

Int. Cl .:

HOIh

German class: 21c-35/07

Number: 1229 162

File number: C 32620 VIII d / 21 c

Filing date: April 10, 1964

Opening day: November 24, 1966

The invention relates to a device for switching off alternating currents without sparking with a main switch that can be operated at will and two parallel secondary lines, each with a Asymmetrical conductive element included in series with a secondary switch or an asymmetrical conductive element, which also has the function of the secondary switch, the flow direction of the two asymmetrically conductive elements in the secondary lines are opposite to each other.

In such switching devices with a main switch and two parallel to this Secondary lines, each containing an asymmetrically conductive element in series with a secondary switch, it is already known to synchronize the secondary switch with the main switch when switching off.

In a known switching device, this synchronization is carried out so that the secondary switch after opening the main switch in that Open current half-cycle in which your secondary line through the asymmetrically conductive element is kept de-energized.

The development of technology in such switching devices has therefore gone to the To switch the main switch completely without any nuisance. This makes it possible to use a simple main switch To use separators.

When switching devices with main switches and secondary switches on again, this becomes Closing these switches made at the same time. The main switch takes over the power supply, and the secondary lines with their secondary switches and the asymmetrically conductive elements not burdened.

But z. B. by one of the known switching devices described a short circuit standing consumer is switched to the mains, the holding force of the is used as the main switch simple disconnector are not sufficient to maintain the current flow via the main switch, until protective devices connected in series with the switch have interrupted the current. Rather, it comes to lifting the contacts of the main switch, and the secondary lines with their Auxiliary switches and the asymmetrically conductive elements are caused by the high short-circuit current burdened.

The asymmetrically conductive elements must be dimensioned for the occasionally permissible maximum current, for example five times the nominal current. Asymmetrically conductive elements for such currents are, however, quite expensive and have devices for switching off without a spark
Alternating currents

Applicant:

Compagnie Generale d'Electricite, Paris
Representative:
ίο Dipl.-Ing. H. Leinweber

and Dipl.-Ing. H. Zimmermann, patent attorneys,
Munich 2, Rosental 7

Named as inventor:
Blancpain Andre,
Doniol Michel,
Saint-Quentin, Aisne (France)

Claimed priority:

France 11 April 1963 (931291 Seine)

thus a significant proportion of the total costs of the switching devices described. Under pressure they are now destroyed by the short-circuit current, the switching device has become unusable and must be repaired expensively.

The invention therefore sets itself the task of switching devices for switching off without spark of alternating currents, the secondary lines and thus the asymmetrically conductive elements not only when Switch off, but also to keep it de-energized when switching on.

According to the invention, this object is achieved in that a circuit breaker is used as the main switch which when switching on, even on a short circuit, keeps the secondary lines unloaded.

The use of a circuit breaker leads because of its considerable compared to a simple disconnector better holding force to the fact that the main switch even when switched on to short circuit the Current management takes over until a protective device to be connected in series has responded. For this purpose, according to a further feature of the invention with the switching group from main switch and Secondary lines the coil of an overload protection relay and another protective element against short-circuit currents, preferably a fuse, connected in series.

609 728/275

If, for example, the safe separation is carried out by the fuse in the event of a short-circuit current 800 Ms, a circuit breaker is selected as the main switch according to the invention, which with this current has a hold time of 1 second. So the secondary lines actually remain unencumbered, and for the There is no risk of destruction of expensive asymmetrically conductive elements in the secondary lines.

According to a further feature of the invention, the overload protection relay has a against higher Amperages falling fall time-amperage characteristic, which at a certain selectable Current intensity the separation time-current intensity characteristic of the fuse, which usually falls even more steeply cuts.

This avoids having to replace the fuse too often, as the overload protection relay due to its electromagnetic characteristics it drops before it due to the thermal Characteristic for the destruction of the fuse.

Further advantages of the invention emerge from the following description. In the drawing is the Invention shown by way of example, namely FIG. 1 to 4 electrical circuit diagrams and

Fig. 5 shows the operating characteristics (current intensity, time) of the organs R and F which are included in the circuit structure of the switch.

The characteristics according to FIG. 5 intersect at point M. The corresponding current intensity I ₁ is close to and higher than the occasional operating _{intensity / occ} , which denotes the highest current intensity that the switch must withstand during normal operation, e.g. B. at least ten times the rated current J _n (control of a squirrel cage motor with interrupted operation). The current intensity I ₂ also shown is close to and slightly above the value Z ₁ .

In the F i g. 1 to 4, the reference symbols A 1 and A 2 represent the connection terminals of the switch on the power source side, and B1 and B 2 those on the consumer side. The switch of FIG. 1 comprises

1. a mechanically operated breaker (i.e. with moving contacts), denoted by P. and, due to its structure and dimensions, has the ability

to withstand a high closing power, so that it can be closed and in the short-circuited circuit in which the flow of a high short-circuit current is to be assumed, remains closed during the time that the protective element F needs to limit and switch off this current, the current I ₂ to withstand until the switch turns it off,

constantly withstand the flow of the nominal current I _n;

2. a protective element labeled F - preferably a breaker with fuses of high separation force - to ensure the protection of the switch and the system against short circuits. It is chosen such that

it is not effective for those current intensities and ranges that correspond to the operating conditions described on the basis of the switch, ie in particular for the nominal current / "and, taking into account an existing relay R, for any current intensity not exceeding the value I _1,

it has a coefficient of limiting the sufficient current so that in particular in the presence of an assumed short-circuit current which is the one for the separation capacity of the switch is reached, the limited amperage is lower than the Closing power of P,

it has already come into effect at a strength above I ₂ before the breaker P opens under the action of the relay R;

3. a maximum strength switching time relay (relais maximum d'intensite temps inverse), denoted by R , for opening the interrupter P in the event of impermissible excess strengths (overloads);

4. two asymmetrically conductive elements Dl and D 2, preferably semiconductor diodes, which are connected in parallel to the interrupter P, in such a way that the direction of passage of one is opposite to that of the other. They are chosen so that they can withstand a symmetrical polarity change of the current I _2;

5. two switches 51 and 52 connected in manner known per se in each case in series with Dl and D. 2 They are dimensioned in a known manner such that they can withstand a symmetrical pole change of the current I _2.

The opening of each breaker is synchronized with the current pole change by suitable means, namely during the pole change, when the asymmetrically conductive element with which it is in series is switched, does not conduct.

The switch works in a manner known per se as follows: In order to enable current to pass through, the interrupter P is closed at any point in time. This has - via suitable means - the closing of the interrupters 51 and 52 as a result. In this state, the voltage drop in the interrupter P, that is between A and B, is sufficiently low that there is no noticeable conduction of D1 and D 2 in the direct direction.

To interrupt the passage of current, the interrupter P is opened at any point in time. The current is now switched depending on its flow direction either on the element DL, or D. 2 The opening of P therefore takes place with practically no arcing at its contacts. To simplify the description, it is assumed that the element Dl is affected first. At the end of the line pole change of Dl, the corresponding breaker 51 is given the command to open by suitable means. This opening takes place before D1 starts conducting again. It is therefore causes virtually also without arcing at the contacts of D1, because 51 only very weak countercurrent flow of Dl off. During this pile change, does not conduct in which Dl, D 2 ensures the current passage, then the pile change D 2 becomes non-conductive at the end. The opening command is now issued. This opening takes place before D 2 becomes conductive again. Consequently, there is also practically no arc, because in this case too the interrupter only separates the countercurrent of the asymmetrically conductive element.

In the case of closing to a short circuit, the interrupter P can be closed, which has a sufficient closing capacity. The protective element F contributes to eliminating the fault. The elements Dl and D 1 are not traversed by any current that could damage them. The opening of P, S1 and 52 is automatically guaranteed by suitable means, which, for example, start from a contact controlled by the element F.

If a short circuit occurs while the switch is holding the line closed, then F can maintain a sufficiently closed position. The error is eliminated by F , as described above.

In addition, it is provided within the scope of the invention to equip the switch with devices and elements whose effects are superimposed on those described above, so that additional properties and advantages are given to it. An example is shown in FIG. 2 shown. Protection and signal ao elements / 1 and fl, such as circuit-breakers with fuses, which are connected to so-called "voyants" melt indicators, e.g. B. with firing pin, are each inserted between A and Al and between A and Dl. They represent an effective means to indicate on the one hand that the elements D 1 or Dl are defective and on the other hand to protect Dl and D1 from short circuits if - which is very unlikely - the automatic opening of P due to a short circuit before the intervention of F takes place: in this case it is sufficient to choose them in such a way that they come into operation before the elements!) Are subjected to an impermissible stress, ie a stress that is higher than that which corresponds to _{a symmetrical pole change of the current / 2} .

According to the in F i g. 3, the units of asymmetrically conductive elements and synchronized interrupters D 1-51 and .D 2-52 are replaced by thyratrons TH ₁ and TH ₂ . These thyratrons can be solid thyratrons, such as. B. thyristors, trinistors, etc., or be gasthyratrone. Your control circuit is shown al and al by numerals. It is known that if necessary, the course A-TH-B can be made conductive or non-conductive by suitable action on the control voltage. In particular, if the conductive state is assumed, when the value of the control voltage is lowered below the ignition threshold, the thyratron is no longer conductive when the corresponding current changes polarity when it is conducted in the direct direction. Thus, it can be seen that it can function with good success as the synchronized breaker 5 used in the first embodiment.

Just as in the above with regard to the switch according to FIG. 2, it is provided within the scope of the invention to equip the switch with element thyratrons, such as / 1 and jl, which can give it certain advantageous properties. A corresponding switch according to the invention is shown in FIG. 4 shown.

Claims (3)

Patent claims: 1. Device for the spark-free switching off of alternating currents with an arbitrarily actuatable Main switch and two secondary lines parallel to it, each one asymmetrical conductive element included in series with a secondary switch or an asymmetrically conductive one Element that also has the function of the secondary switch, the direction of flow being the two asymmetrically conductive elements in the secondary lines are opposite to each other, characterized in that the main switch (P) is a circuit breaker that is used in Switch on, even in the event of a short circuit, which keeps the secondary lines unloaded. 2. Device according to claim 1, characterized in that with the switching group of main switch (F) and secondary lines, the coil of an overload protection relay (R) and another protective element against short-circuit currents, preferably a fuse (F), are connected in series. 3. Device according to claim 2, characterized in that the overload protection relay (R) has a falling time-amperage characteristic falling against higher amperages, which at a certain amperage (Z ₁ ) the usually still falling separation time-amperage characteristic of the fuse ( F) cuts (Fig. 5). Considered publications:
German Patent Nos. 638 981, 693 364;
German explanatory documents No. 1160 923,
1172345. 1 sheet of drawings 609 728/275 11.66 © Bundesdruckerei Berlin