DE726792C - Device for regulating an electrical network size - Google Patents

Description

Device for regulating an electrical network size for the automatic Regulation of electrical network variables, such as the network reactive load, network voltage, etc. Reactors or power capacitors are a large number of relay controls has been developed. Either the immediate network variables, such as the Reactive current, the apparent power, the offered mains voltage, or also indirect Network variables such as the time of day, the harmonic content of the network voltage characteristics, the power to be transmitted in high voltage networks, or combinations from the above network variables used as control variables. As control devices can either relays, contact measuring devices or relay-like reactive work, real work, Voltage hour counter or current hour counter can be used.

With great economic advantage one used for automatic Capacitor or inductor control systems, preferably the last-mentioned relay-type Counters, especially since their response speed is not constant, but rather dependent on the load is without special timing elements would be required. Such under the name Reactive power relays built up by reactive consumption meters develop when they are used in reactive power control systems a corresponding to the reactive power to be compensated Torque generated by the drive system via a worm wheel with the interposition a slip clutch as well as a translation into slow speed drives a camshaft.

Is the reactive load incidence of an inductive type in capacitor control systems z. B. as a result of the activation of motors, the drive system rotates forward and switches mercury interrupter tubes and thus capacitors through the camshaft on the grid, occurs as inductive reactive power. On the other hand, if the motors are switched off, so the counter rotates backwards and switches the last connected capacitor first off again. With the described arrangement show the the camshaft attached cam disks recesses on which of the growing Number of steps have longer recesses along the outer circumference.

Only then do the mercury interrupters close the circuit of the Capacitor contactor if their rollers result from the aforementioned recesses Forward rotation of the cam to wander out and get on the outer periphery move the cam disc further. Give the most recessed cams the switching command for switching on the last spatially arranged capacitor stages also only last. In the above arrangement, the services must per switching level with consideration of other characteristic properties of the reactive power limiter be the same size. There are therefore for z. B. seven switching stages seven cam discs with seven mercury interrupters, seven capacitor contactors and seven capacitors needed.

However, it is known to maintain the aforementioned seven Mercury interrupters with the help of intermediate relays in special circuit with three capacitors of equal power and a fourth capacitor of half power also achieve a total of seven equal performance levels. It is also known by means of z. B. an eleven step switch using an intermediate relay in special circuit by means of four unequal capacitors with powers in relation i: a: 3: 5 to achieve a total of ten equal performance levels. One reached through these two circuits reduce the number of capacitor contactors required, However, a larger number of intermediate relays and a greater switching frequency must be used the individual capacitor contactors, which have to start in the intermediate stages, accept.

The invention relates to the improvement of such a control device with any number of approximately equal stages using a control shaft, from a control relay directly or via a drive motor for switching control means of unequal size in their performance, e.g. B. capacitors, inductors etc., before or. is driven backwards. The invention is characterized in that that to avoid the unnecessarily frequent switching on and off of the control means smaller Performance in upward and downward regulation through the respective smaller control means for as long an assigned mechanical or electrical relay is prevented from engaging, like the need for compensation or excess, the amount of the next larger control means exceeds, and that with upward regulation after reaching the initial switch-on of the last, generally the largest control means, a final adjustment of all control means of smaller size is enforced.

So far you had to z. B. for the smallest capacitors in a set accept an extremely high switching frequency, since these small capacitors are always used to cover intermediate reactive power levels. These Switching is therefore preferably only suitable for systems with reasonably quiet and rarely changing nature of stress. According to the invention, you can do that so far in the event of strong load changes at the start of operation, the end of operation and during operation unavoidable run-through of all control levels to the required minimum and also for short-term load fluctuations during operation Occurring higher switching frequency for the control units with the lowest stage power avoid or reduce to a tolerable level. Nevertheless, even with small, Slowly arising reactive load differences compensate for small stage power possible, whereby the reactive power limiter is both sensitive to boiling (starting quickly) as well as insensitive (starting slowly). Also will in the present circuit when upward regulation after reaching the for the first time Switching on the last, generally largest control unit, control capacitor or Regulating choke coil, etc., corresponding stage a final regulation of all controlled variables of smaller Step power forced despite the greatest reactive load. If there is a fault in one the capacitor circuits will switch on the next higher control levels and Undisturbed further work and regulation of the facility achieved.

The invention is illustrated in the drawing, for example.

In Fig. I the inventive concept is on a reactive power limiter A applied. The start-up limitation is controlled by the centrifugal switch ä, 9 and io with different response values, with a final adjustment of the small capacitors C after reaching the first switch-on the largest Control unit belonging level is guaranteed. With this circuit, the traversal unnecessary intermediate stages with large inductive or capacitive reactive load changes. Nonetheless, the intermediate stages for small inductive or capacitive reactive load lengths as the output stages are adjusted without further ado.

The reactive power limiter has four main stages in economy circuit with associated regulating capacitors C, whose performance in the present case are graded according to a geometric series to 100, Zoo, 400 and 8oo kVar. Between the successive control stages achieved equally large differences in performance which in the present case amount to 100 kVar from step to step, let the limiter start forward with an inductive load of 100 kVar and start backwards when a capacitive reactive power of 5o kVar is exceeded. The control shaft of the limiter has four main stage disks Al, A2, A3 and A4, which the associated mercury interrupters for tilting and thus for closing the actuating circuit of the associated remote switch of the regulating capacitor to be controlled as soon as the role of the mercury protection is no longer on the inside, but on the outside Part of the arc of the stepped pulley unrolls. But the three small capacitors can due to the assigned stepped pulley Al to As only then in the lower control step range to intervene when the associated centrifugal switch 8, 9 and io are closed. Instead of the quiescent current circuit, an open-circuit current circuit could naturally also be used the centrifugal switch can be applied.

The intervention of the 100 kVar capacitor is now carried out according to the invention the centrifugal switch B monitors. When the meter shaft on which the Centrifugal contacts are in the appropriate arrangement and storage, as a result of the - reactive load that is greater than the reactive power of the second regulating capacitor von Zoo kVar, assuming a corresponding peripheral speed, opens through corresponding spring preload set to a response value of Zoo kVar Centrifugal switch controls the actuation circuit of the remote switch of the ioo-k '\ 7ar capacitor. Incidentally, the centrifugal switch can either be on the shaft of the actual Reactive power limiter or on the shaft one in the same system of the the same reactive power flow meter with associated drive shaft, possibly can be applied quickly with the interposition of translations. At a Voltage regulating device is one of the shaft one connected to the same busbar connected voltage hour counter.

To acceleration forces caused by sudden load changes cause the centrifugal switch to respond unintentionally, render it ineffective, Timers will be interposed, but they have a shorter expiry time must, as the reactive power limiter in the worst case, d. H. at the greatest Reactive load required to continue running from one level to the next.

The centrifugal switch 9 is set so that he only then his Contact opens when a little more reactive load occurs than the compensation power of the next largest, i.e. the 40o kVar regulating capacitor. So come in Reactive load difference of, for example, 45o kVar, then the 100 kVar capacitor by the centrifugal switch 8 and the 2oo kVar capacitor by the centrifugal switch 9 prevented from switching on. The centrifugal switch io opens its contact only; if the reactive load is greater than the compensation power of the fourth Capacitor, namely greater than 8oo kVar.

The centrifugal switches speak of course both with inductive as well as the same large capacitive reactive load change, d. H. both for forward as well as when the reactive power limiter or voltage limiter is running backwards or the like.

Assume that, for example, from standstill with a inductive reactive load o at the start of operation immediately by switching on motors If there is an inductive reactive power requirement of 85o kVar, only the fourth stepped disc can A engage the 8oo kVar capacitor as the last, largest regulating capacitor no start-up limitation control or monitoring is assigned. Switching on the regulating capacitors for ioo, äoo and 4ookVar are activated by opening the centrifugal switch 8, 9 and io blocked. However, the 8oo kVar capacitor is only switched on when the controller has reached step position 8. After switching on SookVar there is only 5o kVar of inductive reactive power left. So the limiter is coming at level 8 to a standstill. Is done by switching on another large motor 45o kVar reactive power is required, centrifugal contacts 8 and 9 the regulating capacitors controlled by A1 and A2 when running through the next control stages for ioo and 2oo'kVar prevented from intervening. Only the one controlled by A comes 40o kVar capacitor - to take effect, at the earliest in position i2. It remains an uncompensated reactive power of 5o kVar ind. The controller comes to a standstill.

By switching on additional reactive power consumers, an inductive reactive power of 350 kVar may now occur. By arranging three auxiliary stages, the first from position 12, the second from position 1q. and their third close from step position 15 to working circuits, the control step 12 gives the possibility to switch on the 200- and 100-kVar capacitors by connecting lines parallel to the centrifugal switch via the contacts of the auxiliary stages H12, H14 and H15 be guided. As a result, on the penultimate, fourteenth stage, the auxiliary contact H14 lying parallel to the centrifugal switch 9 responds, as a result of which the 2oo kVar regulating capacitor controlled by A2 is switched to the mains; the inductive reactive load drops from 35o to i50 kVar. On the last control stage 15, the first regulating capacitor for 100 kVar is switched on by the auxiliary contact H15, since the stage switch A1 is also closed at the same time. The total reactive power is thus up to 5o kVar ind. compensated, ie the limiter comes to a standstill. The circuits of the auxiliary step disks can also be closed by the main step disks, whereby the disks H12, H14, H15 can be saved.

Assuming that the limiter is in position 15 and has to regulate a capacitive reactive load excess of 85o kVar by switching off numerous motors, the limiter A rotates backwards and goes through stages 15 to 12, so that after reaching control stage 12 only a capacitive excess of 450 kVar remains. The limiter A continues to work in reverse; in position ii the 4oo kVar capacitor is switched off. At level 12 the 100 and 200 kVar capacitors should actually come into play; however, the 100 kVar capacitor is blocked by the centrifugal switch 8 because the reactive load is still too great. This results in a reduction in the capacitive excess from -q.50 to -25o kVar. The limiter A thus rotates back from stage ii via stage io to stage 9, in which case the 2oo kVar capacitor output is also switched off in the latter case. There remains a capacitive reactive load excess of -5o kVar. Since this is within the run-up and return limits of the limiter, limiter A comes to a standstill. If the reactive load continues to drop, the governor behaves in a similar way with the associated start-up limitation lock through the centrifugal switch.

It should be noted, therefore, that both the upward and the In the event of strong changes in the reactive load, the downward regulation is to switch the Intermediate levels are reduced to the necessary minimum.

During the interlocking of the start-up in the case of strong changes in the reactive load unneeded control units of small and very small power levels to indirect ones Way done by using centrifugal force, one can accomplish the same purpose also achieve in an immediate way. You can use the start-up limitation here, for example by reactive power or voltage relays, which depend on the network size to be controlled can be influenced, controlled, with the response and drop-out values or the maximum and Minimum contacts are set so that when the power value of the each larger control means the respective smaller control means immediately or after a certain time that can be staggered by opening the actuating circuit the remote switch associated with this smaller control means is prevented from intervening will. Here, too, it is only necessary to ensure that in order to avoid oscillations the blocking occurs earlier than the control means to be blocked during normal operation of the switching process by the limiter A would be used. The control is of course designed in such a way that the necessary shutdowns only occur with upward regulation carried out before the next larger capacitor is switched on.

In FIG. 2, the centrifugal switches of FIG. I are immediately through Reactive power relays B and C replaced, with the maximum or Minimum contact of the Reactive power limiter B when exceeding -1-20o kVar with interconnection of a timing relay responds. The maximum and minimum contacts of the reactive power relay C respond when + qoo kVar is exceeded, also preferably with a time delay. Otherwise, the operation of the reactive power relays B and C is the same as that of the centrifugal switches 8 and g mentioned earlier.

Furthermore - a monitoring and start-up limit control for the small control units are also achieved in an electrical manner in that one in place of the time-delayed centrifugal switch of Fig. i or the time-delayed Reactive power or voltage relays of FIG. 2, for example, reactive power limiter or voltage limiter used. Here are the response values of the limiters and the auxiliary limiter for forward and reverse run is set so that when the limit is exceeded the power value of the next larger controlled variable, control capacitor, control reactor etc., the smaller controlled variable in each case staggered according to a certain load-dependent Time through opening the control circuit of the remote switch this controlled variable is prevented from intervening. This is done by appropriate shaping of the stepped washers of the preferably quick-responding auxiliary limiter oscillations thereby avoided that the blocking of the intervention of the smaller control means already is carried out before the latter is carried out in the normal course of the control process by the Main limiter A would have been used.

According to FIG. 3, a start-up monitoring limiter is assigned to each stepped disk with the exception of the last of the main limiter A, so that a limiter B belongs to stepped disk A1 and a limiter C belongs to stepped disk A2. The main limiter A has three step discs with three associated regulating capacitors with the power ioo: 200: q.oo kVar. The limiter A is again the actual working limiter, the start-up and return limits of which are designed for the output of the first regulating capacitor of 100 kVar. Exactly as in the example in FIG. 1, the inductive response value of A may be 100 kVar, the capacitive return flow value may be 50 kVar. The start-up and return limits of the first start-up monitoring limiter B are set in exactly the same way as with the centrifugal switch 8 or reactive power relay B so that they respond when the power value of the next larger controlled variable is exceeded, i.e. at + 2oo kVar and after a certain time the actuating circuit of the remote switch closes Open the monitoring 2oo kVar capacitor. The start and return limits of the second auxiliary limiter C 'are set according to the performance of the third control means, ie in the present case so that they respond when -Iq.oo kVar is exceeded.

According to Figure 3, the circuit of the first Ouecksilberschaltrohres of the limiter A via the first O mercury switching tube of the limiter B. With this series connection. of the two mercury switching tubes receives the stepped disk of the switching tube of the limiter B is of such a special shape that the associated mercury switching tube Bi closes a circuit for as long as, for example, with an inductive reactive load the inductive start-up limit of the limiter B is not exceeded. So it can If necessary, the interrupter A1 switches on the first regulating capacitor for 100 kVar if the start-up limit of limiter A is exceeded. If more than twice the reactive load occurs, i. H. is the inductive reactive power requirement of the system to be compensated so large that the inductive start-up limit of the. Start-up monitoring limiter B is exceeded by + 2oo kVar, this starts up; its camshaft rotates itself, and after a certain time, which is generally kept shorter than the response time of the switching tube A1 of the limiter A, the mercury tips over Switch tube of the limiter B downwards. So it will - the short time afterwards from control command given to interrupter A1 of limiter A for the ioo-kVar regulating capacitor not executed.

However, the second control tube A2 of the limiter A can and should intervene unless the reactive load is so great, namely greater than q.oo kVar that the control tube A2 also works through the associated start-up monitoring switch tube C1 of the limiter C 'is prevented. The cam disc for the switch tube Cl has such a shape that after a certain time it closes the circuit of the associated switching tube A2 of the limiter A interrupts. Here, too, should the interruption generally take place faster than the interrupter A2 of the limiter A when moving on from one level to the other, d. H. thus also in a shorter time than the interrupter Al of the limiter A is required for intervention.

Since the monitoring limiters now come to a standstill after their relay function has been exercised and do not return to the initial position required for the fulfillment of further monitoring tasks, each auxiliary limiter is brought into its initial position after the respective forward or reverse movement that its reset relay through the changeover contact of the power-related switch tube A2 or AS is de-energized until the respective auxiliary limiter has definitely returned to its starting position. The limiter A has reached level 5 in the position shown, while the start-up limiters B and C rest in their initial position.

The economy circuit and start-up limitation control according to FIG. 3 works as follows: If an inductive reactive power requirement of 250 kVar immediately occurs from the idle state without reactive load occurrence at the start of operation, the threshold value of the limiter B is exceeded. Its normally closed contact is therefore opened before the switching contact A1 could connect the first regulating capacitor to the network. After a certain time, however, the limiter A switches on the switching contact A2 and thus a time relay A2 (step position a). As a result, on the one hand, the second regulating capacitor of Zoo kVar is switched on, so that only 50 kVar remain to be compensated, and on the other hand, the changeover contact of .q is interrupted. the circuit of the reset relay B -, # by means of the adjustable time relay A_ 'until the limiter B has definitely returned to its starting position. All controllers now remain at rest.

If an inductive load occurs again, so that despite the effectiveness of the second control capacitor an inductive reactive load of in turn z. B. d.5o kVar remains to be compensated, the limiter B starts up again and prevents this Multiple switching on and off of the first regulating capacitor for 100 kVar. It speaks now the limiter C on, opens the contactor coil of the 2oo-lcVar regulating capacitor, so that the reactive load to be compensated increases to 65o kVar. Under the influence As a result of this reactive load, the 4oo kVar regulating capacitor switches itself on very quickly Intervention of switching tube A3 (step position d :) a. So it stays after switching on of 4.oo kVar capacitor power only an inductive reactive power of z5olcVar to compensate left. When the tap position 4 is reached, the reset relay is activated from B by tilting back the interrupter.-l. as well as by switching on the interrupter A3 dead. The limiter B can therefore no longer take effect. In the meantime the main limiter continues <q. By actuating the interrupter A, is obtained the ioo-kVar regulating capacitor sends the switch-on command; but this can because of the locking cannot be carried out for the time being due to the auxiliary step washers H4 and H7. In the meantime, the limiter A continues to work and reaches step position 5 Step position 6, d. H. the second regulating capacitor is switched on so that the total reactive power drops to 5o kVar.

If the inductive reactive load falls again, for example in total 300 kVar, limiter B cannot now move out of its starting position again start because the reset relay is due to the tilted position of the switching tube .d3 remains dead. In addition, the effect of the limiter B is through the auxiliary stages H4 and H, switched off. The limiter A continues to work and comes to the Step position 7, d. H. it becomes the last remaining capacitor of 100 kVar through switching tube A, switched on. This makes the inductive Reduced idle load on Zoo kVar. However, there are no other capacitors are present, the camshaft comes to a stop; it puts those in the limiter A built-in slip clutch so that the meter's drive system continues to run undisturbed can. In the present circuit, in the example chosen, the Avoid going through stages i, 3 and 5. Nevertheless, the intermediate stages will be leveled out with small changes in the reactive load as well as switching on the small and smallest Control means at the end of the control stages, d. H. after switching on the last, generally the largest control means guaranteed. The same applies, of course, to Backward rules.

By the way, plan can also do without the supply of the reset relay Dx of the auxiliary limiter B via the break contact of the switching tube, since the auxiliary limiter B by the auxiliary stages H, and H; ineffective, ie is unlocked.

As far as systems are concerned in which reactive load or voltage fluctuations can be expected to be small, the centrifugal switches 9 or reactive power or voltage relays C or the auxiliary limiters C can be omitted in order to save if there are generally no larger reactive load fluctuations than occur in the range from o to: loo kVar. If the work limiter <d has more than three main stages, you only need to provide as many relays C , D , etc., as in all probability the greatest reactive load fluctuation or voltage fluctuation or the like that will occur. Conversely, even if the operating conditions change, the circuit can be expanded by adding the start-up control relays set to higher response and return values.

The previous statements extended to a gradation of the Performance of the controlled variables according to a geometric rule. However, it can also deviating, differently designed, for example arithmetic or other Rows for grading the performance of the controlled variables are used as a basis.

The economy circuit and start-up limitation control can also be applied to the already proposed electrical series connection of two reactive power limiters of which the first as a fine controller and the second as a coarse controller is trained.

The present economy circuit naturally does not only need to previously treated switch camshaft of the reactive power or. Voltage limiter to remain limited insofar as they are directly through reactive consumption or voltage consumption meters are driven. Rather, it can easily be applied to the counter-like Use control devices with downstream switching devices, the latter through a motor can be driven and likewise a shift shaft with have up to 15 mercury interrupter tubes. The economy circuit continues also on the other switching shafts, which are driven by a drive motor be, the actual drive motor z. B. by reactive power, voltage relays o. The like. Caused to run forward or backward and by a brake relay to Is brought to a standstill.

Need from the counters or from the drive motors described above not only switching shafts with stepped disks and mercury interrupter tubes turned closed but shift drums with contact tracks can also be driven, which can then receive recesses, segment-like conductor inserts, etc. Around Avoid incorrect switching caused by earth faults in the actuating circuits of relay controls can occur, the entire economy circuit and start-up limitation control can also be designed with two poles.

Finally, the behavior of the invention is also of great importance Control device in the event of malfunctions on one of the control capacitors, capacitor switch etc. as a result of short circuit, overload, etc. In such cases, the capacitors As is well known, circuit breaker with thermal and magnetic quick release is connected upstream, the electrical and mechanical reclosing locks get a new switch-on and thus to prevent pumping. While now with the known facilities to regulate capacitors with different capacities a partial or total shutdown the capacitors already under voltage may be necessary or as a result of the discrepancy between the measured values of a model circuit and the regulated capacitor output also pumping occurs, switches the control device according to the invention readily includes the ones to be considered next higher control level.

The entire system can continue to work unaffected and also the full compensation power of the healthy capacitors during the malfunction make available to the company, so that no Disadvantages of a tariff, technical or economic nature, e.g. B. increased reactive power charge, excessive voltage drop, increase in transmission losses, etc. occur. This is particularly important for unattended systems.

However, an acoustic signal is used to identify the disturbance or at least optical signaling device and also per capacitor remote switch a package switch for switching off the closing magnet and the zero voltage coil so that you can work on the defective regulating capacitor circuit in the event of a malfunction can. If the package switch is used for three positions (off, manual and automatic operation) provided, you can also switch from automatic to manual operation in normal operation switch.

Claims (1)

PATENT CLAIMS: i. Device for regulating an electrical network size in any number of approximately equal stages using a switching shaft that is controlled by a control relay directly or via a drive motor for switching control means of unequal size, e.g. B. Capacitors, inductors, etc.,. is driven forward or backward, characterized in that to avoid the unnecessarily frequent switching on and off of the control means of small power when up and down regulation, the respective smaller control means is prevented from intervention by an associated mechanical or electrical relay as long as the Compensation requirement or excess exceeds the amount of the next larger control means, and that with upward control after reaching the level associated with the first switching on - the last, generally largest control means, a final adjustment of all control means of smaller size is forced. Device according to claim i, - characterized in that during upward regulation after reaching the stage associated with the first switching on of the last, generally largest regulating means, a regulation of all regulating means is forced by the effect of the relay start-up limiter switching off auxiliary contacts, whereby z. B. with a geometric series of control means in the ratio 1 :: 2: 4: 9, the activation of stage d. only takes place in control position 12, which simultaneously enables level 2 and i to be switched on, level 2 is only switched on in control position 14, with level i being enabled at the same time, and level i only in the last Control position 15 is switched on. 3. Device according to claim i and 2, characterized in that the start-up limitation is effected by a centrifugal switch built on the shaft of a counter system or the like that is influenced by the network size to be controlled, with a time delay such that when the size of the next larger control means, capacitor, choke coil is exceeded etc., the respective smaller control means is prevented from engaging by preferably opening the actuating circuit of the remote switch of this small control means, in order to avoid oscillations, even before this smaller control means would be used in the normal course of the switching process. 4. Device according to claim i to 3, characterized in that the response values of the centrifugal switch can be adapted to the graduated requirements by changing the spring forces of the individual centrifugal switches. 5. Device according to claim i or 2, characterized in that the start-up limitation is effected by reactive power or voltage relays influenced by the network variable to be controlled, and that the response and drop values "or maximum and minimum contacts are set so that when the value is exceeded Power value of the next larger control device, capacitor or throttle, the respective smaller control device is prevented from intervention immediately or after a certain, possibly staggered time lapse by opening the actuating circuit for the remote switch of this small control device, in order to avoid oscillations, even before this 6. Device according to Claim 1 or 2, characterized in that the start-up limitation is effected by voltage or reactive power limiters influenced by the network size to be controlled, preferably with a delayed start-up, the response values for forward and backward running are set so that when the power value of the next larger control means, control capacitor, control inductor, etc. is exceeded, the respective smaller control means is prevented from intervening after a certain load-dependent staggered time by opening the actuating circuit of the remote switch, and that by appropriately shaping the step control disk of the preferably fast-responding auxiliary limiter in order to avoid oscillations it is achieved that the blocking of the intervention of this smaller control means has already taken place before it would have been used in the normal course of the control process. 7. Device according to claim 6, characterized in that each auxiliary limiter is brought into its starting position after the forward or reverse run characterized in that its reset relay through the changeover contact of the power-related control contact, for. B. a stepped silver switch tube (A2 or As) is temporarily de-energized until the respective auxiliary limiter is safely returned to its original position. B. Device according to claim i or the following, characterized in that in systems with relatively low voltage or load changes only the most exposed, generally smallest control means by a mechanical or electrical relay, centrifugal switch, reactive power or voltage relay , Reactive power or voltage limiter, etc., are prevented from starting. 9. Device according to claim i or the following, characterized in that both a fine and a coarse controller replacing it is provided with means to avoid unnecessary switching on and off. ok Device according to claim 1 or the following, characterized in that step disks with segment-like conductor inserts serve as switching grids to control the switching means, or that switching roller contact tracks with recesses and associated mercury interrupter tubes or with segment-like conductor inserts are used. i i. Device according to claim 1 or the following, characterized in that the control is two-pole instead of single-pole as before, both poles having the same embodiments with regard to the stepped disks and mercury switching tubes or the segment-like inserts in the stepped disks or the switching roller contact tracks (recesses or segment-like inserts).