DE1151041B - Arrangement for interrupting DC and AC circuits - Google Patents

Description

It is known in arrangements for interrupting inductances containing equal or AC circuits to switch a pulse circuit parallel to the interruption point, which is at least a capacitor charged when the interruption point is closed and means for closing and opening the pulse circuit to emit a pulse current in the opposite direction to the current to be switched off at the moment of the current interruption. Such arrangements are improved according to the invention in that the capacitor has one a switching point and an ohmic resistor are connected in parallel in series, over which the capacitor moves before it reaches a voltage that is dangerous for its insulation strength at the inductance caused by the circuit to be interrupted after the discharge of the capacitor is discharged via the point of interruption.

By the invention it is achieved that the capacitance of the capacitor in the pulse circuit alone after the current can be measured, which the capacitor to achieve a current zero crossing has to deliver. The capacity can therefore be matched to the nominal breaking current of the switch. on the voltage that appears on the capacitor after the circuit has been interrupted not to be taken into account, because of the parallel circuit of switching point and ohmic Resistance, an inadmissibly high voltage stress on the capacitor is avoided.

In a known arrangement, in which a charged capacitor has an interruption point is discharged, there is an auxiliary switching point in series with the last. A capacitor is parallel to this switched and also an ohmic resistor. When the auxiliary switching point is opened, the capacitor charged and the resistor switched on in the circuit. Then the charged capacitor switched off by the resistor and discharged via a discharge resistor via the interruption point. It is missing from this known device So a parallel path to the capacitor, which consists of a switching point and a resistor, over which the capacitor discharges after opening the interruption point.

Under certain circumstances it can be useful to connect an additional resistor upstream of the parallel connection of capacitor and voltage limiting device with resistor. For this purpose, a resistor with a variable ohmic value is expediently provided, specifically in such a way that it has an arrangement for interrupting it
of DC and AC circuits

Applicant:

Siemens-Schuckertwerke Aktiengesellschaft,

Berlin and Erlangen,
Erlangen, Werner-von-Siemens-Str. 50

Claimed priority:
Switzerland of December 17, 1953 (No. 113)

Dr.-Ing. Fritz Kesselring, Zurich (Switzerland),
has been named as the inventor

During the duration of the pulse current of, for example (1 ... 2) -10 ~ ⁴ s, it remains practically unchanged at its lowest value, while it increases its value when the compensating current occurs. For example, a resistor made of pure iron or tungsten has proven to be suitable, since both materials are characterized by a high positive temperature coefficient. In the case of iron, a tenfold value of the KaIt resistance can be achieved without difficulty, whereby the residual current to be switched off is reduced accordingly. The arrangement must be made so that the resistor is able to absorb the released magnetic energy of the circuit including the energy still supplied by the power source during the shutdown.

During the shutdown process there is generally at least one charge reversal of the capacitor in the pulse circle. As a result of the dielectric after-effect, this results in a significantly increased electrical stress. A capacitor rated for a correspondingly higher voltage must therefore be used can be used, which is unfavorable in terms of price. This disadvantage can now be avoided that the voltage limiting device is already used before the capacitor is recharged, effective at the earliest, however, at the zero crossing of the resulting current in the interruption point the voltage limit on the capacitor is maintained until the pulse circuit is interrupted again, which can be done, for example, by an auxiliary switch in the pulse circuit.

309 619/196

3 4

When switching off DC circuits, the maximum value U _{c can occur} and from then on it sounds at the value

be expedient, the residual current, which is initially - U from. The resulting voltage U _r = U + U _c

as z. B. exponentially decaying direct current drawn in dashed lines in Fig. 3 below and sounds

. is to superimpose an alternating current, in such a way that over time to zero, so that the auxiliary switch 9

at least one zero crossing occurs. This can, for example, at time E (see FIG. 3) under very low

for example happen that the can be opened from the favorable conditions.

Capacitor of the pulse circuit and the additional ones From Fig. 3 it can be clearly seen that the condensate

in the network existing inductances resulting generator voltage at time D generates a voltage

Oscillatory circuit through the changeable light-ranges that vary according to the size of the magnetic arc resistance of the voltage limiting device and the size of the capacitance of the condenser

vibrations is triggered. sators 8 can assume quite considerable values.

The drawing shows some exemplary embodiments. Either the capacitance of the condenser should be

of the invention shown schematically. Fig. 1 is a significantly enlarge gate or capacitor

first embodiment, whose mode of operation can be selected for significantly higher voltage; is both Hand of the current and voltage diagrams of FIG. 15 uneconomical. The latter measure is mostly

Fig. 2 and 3 is explained, while Fig. 4 is also inadmissible, since voltages above about the

shows another possible execution. 2.5 times the operating voltage to endanger the

In Fig. 1, 1 means a direct current source of the system can lead. Here, the remedial voltage Ό, 2 the load with the resistor R measure according to the invention, in that parallel to and 3 an inductance L. device is placed, for example, at ters, consisting of the current bridge 5 and the fixed the l, 5 times the operating voltage U _s corresponding to stationary contacts 6 and 7. the pulse circuit loading the time S (s. Fig. 3) is to respond, stands from the capacitor 8, the auxiliary switch 9 This can be achieved that the voltage and a discharge resistor 10. Parallel to the capacitor is practically limited to the value U _s capacitor 8 is the voltage limiting device. At the same time, however, with the response of the device U, consisting of the spark gap 12 in the spark gap 12, the resistor 13 in the form of a horn arrester and the resistor 13 are switched on in the circuit, by now a substantial

In normal operation, the switch 4 is closed, Licher part of that originally in the inductance 3 other Auxiliary switch 9 is opened and the capacitor 8 30 collected magnetic energy is destroyed,

a residual current / 'flows through the

polarity marked by + and --- series connection of resistors 2, 10 and 13

the. There then flows a current I = I ₀ (FIG. 3), which is given and can easily be held in such a way that it

is essentially given by the quotient 17/2 ?. for example through the horn spark gap 12 If the current I _{0 is} now to be interrupted, 35 is automatically switched off. Shouldn't this be the

first switch 9 is closed (cf. time point A , if the case A, the auxiliary switch 9 can be

in Fig. 2). An impulse current /, · arises, which makes it possible for it to be able to absorb the residual current,

in switch 4 the current Z _{0 flows in the} opposite direction. The result is only a small fraction of the nominal current

tating current I ₁ . falls off, reaches a first at A , carries on, to switch off.

at B a second NuE pass. The switch 4 40 in Fig. 4 40 means a direct current source, 41 should now be such that the resulting load, 42 an inductance, 43 the main current I _r at least at the second zero crossing B switch with the current bridge 44, the fixed is finally interrupted. From this point in time contacts 45 and 46 and the switch-off winding 47. the current now flows (see 49 'in addition to the ignition electrode 50, the switch 9, the load 2 and the inductive and switching bridge 51. The electrode 49' and the tat 3, the current source 1 and the capacitor 8, the ignition electrode 50 being connected to the secondary winding 52 in series , so that the effective span of a transducer 53, the primary coil 54 of which is the sum of U + U _cg , where U _{co is the} circuit. 55 is the capacitor, 56 and 57 are the voltage across the capacitor at time point B. 50 are resistors, 58 is an arc extinguishing function as shown in FIG. Under the influence of this direction with the blowout coil 59. boosted voltage rises, the current / next (cf.. If the switching bridge 51 of the auxiliary switch 48 at the time B in Fig. 3), reached at the time C a move, for example, by hand to the right, first Maximum, then drops to D and sounds like the pulse circle closes, at the same time the load 2 given attenuation is excited by the resistor 10 and 55 opening coil 47 of the main switch 43. At moderate inductance 42 occurs, a particular capacitor 8 (see FIG. 1) initially discharges; its oscillation damped by the resistor 56, voltage U ₀ has dropped according to the indication of the pulse current without the quenching device 58 for response U _c0 (see Fig. 3, lower diagram) and comes, while with high magnetic energy now continues from until the extinguishing device 58 is completely discharged 60 an arc occurs, at which point in time corresponding to the maximum value of the current switched on by the resistor 57, and thus the maximum magnetic current. After the arc has been extinguished under energy in the inductance 3. Now the supported by the magnetic blowing with the help of the magnetic energy via the load resistor coil 59, the auxiliary switch 48 can current and voltage level 2, the discharge resistor 10 on the condensate 65 without voltage be opened. An automatic Absator 8, where it is reloaded. At the moment when the switching is effected with the HiKe of the converter 53, the current becomes / zero (cf. time D in FIG. 3) one

generated high voltage, creating a flashover between the electrodes 49 'and 50, the immediately the ignition of an arc between the electrodes 49 and 49 'follows. From then on it runs Process again in the manner described.

Claims (6)

PATENT CLAIMS: 1. Arrangement for interrupting direct or alternating current circuits containing inductance by means of a pulse circuit connected in parallel to the interruption point, which has at least one capacitor charged when the interruption point is closed and means for closing and opening the pulse circuit for outputting a pulse current opposite to the current to be switched off at the moment of the current interruption, characterized in that a series circuit consisting of a switching point (12) and an ohmic resistor (13) is connected in parallel to the capacitor (8), via which the capacitor (8) is connected before reaching a voltage which is dangerous for its insulation strength at the voltage caused by the im circuit to be interrupted caused inductance (3), after the discharge of the capacitor (8) via the interruption point (4) onset of charge reversal (Fig. 1). 2. Arrangement according to claim 1, characterized in that the switching point is a spark gap with arc extinguisher. 3. Arrangement according to claim 1, characterized in that in the pulse circle and in series an additional resistor is switched on with the discharge circuit. 4. Arrangement according to claim 3, characterized in that the additional resistance is variable in such a way that it remains practically unchanged for the duration of the pulse current, while it increases its value in the subsequent equalizing current. 5. Arrangement according to claim 1, characterized in that the switching point at the earliest Zero crossing of the resulting current in the interruption point closes and the discharge circuit of the capacitor is kept closed until the pulse circuit is interrupted again for the purpose of reloading the capacitor to prevent. 6. Arrangement according to claim 5, characterized in that the switching point and the interruption point are mechanically coupled in such a way that the switching point is closed only after the interruption point has been opened. Considered publications:
German Patent Nos. 521636, 588 204, 517; French Patent No. 707,718;
British Patent No. 366,966. 1 sheet of drawings