DE1803741A1 - Arrangement for load switching with step transformers or chokes - Google Patents

Description

PLA 68/1279 "■ - 2 -

The faster switching known diverter switch with exclusively expensive controllable rectifiers' (e.g. thyristors) only have the required blocking effect when the current passes through zero, so that load switching only occurs when the Load current is possible; there are separate control devices for this purpose required to get the ignition pulse at the right time from one to the other in the course of the other voter line arranged controllable rectifier to switch.

One of the main disadvantages of the known diverter switches is the diverter switches equipped with mechanical switches view the necessary arrangement of transition resistors, however, load switching is possible at any time is. The diverter switches equipped with controllable rectifiers can manage without transition resistors, but a switchover process can only occur during the current zero crossing using special control devices.

The object of the invention is to use any Switching devices to an arrangement for load switching create that gets by without overshooting resistors and to any Time can be switched.

According to the invention, the problem posed is achieved for the diverter switch equipped with mechanical switches in that uncontrolled synchronization as switching devices Terminal bridges are provided, in the direct current branches at least one mechanical switch each with an inductance is connected in series, and that the negative poles of the mechanical arranged in the direct current branches of both switching devices Switches are connected via an RC element.

With the diverter switches equipped with controllable rectifiers succeeds in solving the problem according to the invention in that uncontrolled rectifier as switching devices. terbrücken are provided, in the Gleiehstromssweige at least each a controllable rectifier is arranged and that the negative poles in the direct current branches of both switching devices arranged controllable rectifier via a

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SADORLGiNAL

SIEMENS AKTIENGESELLSCHAFT

Gain,
Werner-von-Siemens-Str. 50

Our sign:
PLA 68/1279 Ml / Wfr

Arrangement for load switching "with step transformers or chokes · '''"

The invention relates to an arrangement for load switching in the case of step transformers or chokes where the outgoing The consumer line is connected to the two selector lines via a switching device.

For uninterrupted load switching with step transformers and chokes are already known diverter switches, their switching devices from mechanical switches or controllable rectifiers exist.

For load transfer holders equipped with mechanical switches must be an uninterrupted load transfer in several switching steps which requires multiple switches. In addition, the relatively long tax and Switching times of the mechanical switches an overlap of the individual switching steps. To "avoid a short circuit between two winding stages is therefore with such load changes switch a supersonic resistor is necessary. This Überal twiderstand is usually designed so that the The total current resulting from the load and compensating current is mostly about 1.5 times the load current. Due to the voltage drop Due to the transition resistance, a relatively high recovery voltage occurs at the open contact after the arc has been extinguished on, which is usually approximately equal to 3 times the step voltage with the usual design. The arc is extinguished in the first, second or following current zero crossing, dependent from the distance of the Contact pieces. Therefore, a certain time safety interval is necessary up to the next switching step, which in turn results in an extension of the switching time.

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RC-Glled are connected.

By using uncontrolled rectifier bridges only one interruption device required per voter arm. That The RC element forces the load current to commutate from one voter line to the other in the event of a switchover. The forced commutation allows a diverter switch equipped with mechanical switches to be omitted of the over-switching resistor, since during a switching process the arc that occurs when the live switch is opened is deleted immediately as soon as the depending on the Live switch controlled switch in the other selector line closes, and thus the equalizing current between the two winding taps is interrupted in the first phase rise. The current-carrying interruption device thus only switches the load current and only the step voltage occurs as recovery voltage. This allows the mechanical Switch in a diverter switch naoh the invention for a switching capacity are designed because of the known · arrangements possible "5-fold step relaxation and the 1.5 times the load current around the paktor? 1.5 = 4.5 is smaller than in the known arrangements.

To avoid a; Kurznehlusnes between two see two: winding stages may be used with a diverter switch equipped with independent switches the switch in the voter! should only be closed when the switch is in the live Voting line has opened and thus a light on this burns. Servant Lich ^ bogor? is, as already mentioned, only when closing the other scarf t ^ r-s rt'löncht and thereby a uninterrupted load transfer achieved. The one with, the mf? Chanischen Switch in series with live inductance holds during a load current zero crossing the current flow over the as free. current acting rectifier bridge, so that also with a load switchover that takes place during the load flow an arc occurs at the opening switch and thus an uninterrupted load transfer is possible at any time.

0098 3 1 / 0J608

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VLA 68/1279

In the case of a diverter switch equipped with controllable rectifiers, the forced deletion of the controllable rectifiers by the RC element simplifies the switchover control device, since the switchover process is not the same as with the known ones

Load switchers must wait for the natural blocking when the load current passes through zero, but can switch over at any point in time.

So that in each case one of the controllable rectifiers carries the load current continuously, the rectifier in question must be reset by a separate control device after the load current zero crossing ψ . be ignited. >

According to a further embodiment, this control device is unnecessary of the invention by inductances between the negative poles of the controllable rectifier and the negative poles the direct current branches. ;

The inductances hold during the zero current crossing over the rectifier bridge acting as a freewheel upright a certain current flow, so that the natural blocking of the controllable rectifier prevents and thus the continuous The supply of ignition pulses becomes superfluous. '·

The forcible deletion of a controllable rectifier W is achieved by applying a reverse bias voltage, the erasing speed depends on the height of the blocking voltage.

Sine high reverse voltage can with a diverter switch, with its Switching devices in the direct current branches, one controllable each Rectifier and an inductor connected in series are achieved in that the RC element between the negative poles of the controllable rectifier through a capacitor is replaced.

The capacitor forms together with those in the direct current branches the switching devices arranged inductances an LC element. When switching over, the ignition of the non-current carrying controllable rectifier of the discharge circuit of the capacitor is closed and by the discharge

009831/0608

■ · -. '■ BAD ORIGINAL

PLA 68/1279 _ 5 -

current to the with the current-carrying controllable rectifier "in series inductance built up a voltage that the energized controllable rectifier extinguishes Choice of the natural frequency of the LC element can increase the voltage, depending on the requirements of the controllable Rectifier to be adjusted.

The inductances limit beyond the functions described nor the steepness of the current rise to the values permissible for the controllable rectifier.

A sudden change in voltage during load transfer, which is undesirable in some cases, can occur with the diverter switch after the Invention can be avoided by having a continuous Voltage transition from one to the other stage by alternating ignition of the controllable rectifier with different Firing pulse sequence is achieved.

In a load transfer ", for example, to the next higher voltage level, the Zündi is / npulsfolge so as to change, that the duty of the connected to the low voltage level controllable rectifier decreases and the Einschaltdauf ^j r increases the device connected to the higher Spannungostufe controllable rectifier.

The diverter switch according to the invention can advantageously can also be used as a star point load switch. This is achieved by using two multi-phase switching devices Reversed rectifier bridges are provided, in each of whose DC branches at least one mechanical switch is arranged and that the negative poles are arranged in the direct current branches of both polyphase rectifier bridges mechanical switches connected to one another via an RG link are.

In the case of an arrangement on the star point side of the inventive Diverter switches are only two rectifier bridges and thus only two interrupting devices for a polyphase Transformer required. The rectifier bridges themselves

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PLA 68/1279

are extended by the corresponding number of diodes for multi-phase connection. The one to prevent a zero crossing of the rectified load current in the direct current branches of the bridged inductances can with the star point side arrangement of the diverter switch according to the invention do not apply, since with the multi-phase bridge circuit there is no zero crossing of the rectified load current.

In the case of a star point load transfer switch whose switching devices are equipped with controllable rectifiers, one can be used for the commutation of the load current during the switching process on the other selector line necessary deletion of the current-carrying controllable rectifier favorable reverse voltage achieve that between the negative poles of the controllable rectifier and the negative poles of the direct current branches Arranged inductors and the negative poles of the rectifier are connected via a capacitor.

The capacitor forms together with. the inductances in turn an LC element that is already used in the case of the one with controllable rectifiers equipped diverter switch has the effect described.

An improvement in commutation is achieved with the star-point load changeover switches equipped with mechanical switches an additional RC element between the positive poles of the rectifier bridges and those equipped with controllable rectifiers Neutral point load changeover by an additional capacitor between the positive poles of the rectifier bridges achieved.

As soon as the non-current carrying selector contacts of the star point load switch at the beginning of a switching process with the winding taps are connected, the capacitors arranged between the negative poles of the interruption devices and the positive poles of the rectifier bridges charge with opposite polarity on the step voltage. ' During the switchover process, closing the non-powered

8ADORIGiNAL

PLA 68/1279

leading mechanical switch or ignition of the controllable rectifier, the discharge circuit for the capacitors is closed and thus double the step voltage occurs at the current-carrying mechanical switch or controllable rectifier due to the opposing charging of the capacitors. Without the arrangement of the additional RC element or capacitor, the chained step voltage ^{1 would} occur at the contacts of the mechanical switch or at the controllable rectifier. Because of the better commutation, the somewhat higher voltage at the interruption devices is accepted. .

Furthermore, it results in one equipped with mechanical switches Star point load switch according to 'the invention a lower Switching capacity compared to known star point load switches, in which a switching capacity has to be managed per phase which corresponds to the product of 3 times the step voltage and 1., 5 times the load current. With the star point load switch According to the invention, the current-carrying circuit breaker must switch the rectified load current, its effective mean value only equal to 1.33 times the effective value of the load alternating current is. At the contacts of the breaker switch occurs instead of 3 times only double the step voltage, see above that the switching capacity is reduced by a factor of 3/2 · τ - * - τγ = 1.67 is. If one also takes into account that with the known star point load changeover switches for three-phase transformers the load for each changeover process of three switches, with the star-point load changeover switch according to the invention, however, only by one at a time If the break switch is switched, there is a reduction the switching capacity by a factor of 3 · 1.67 = 5.

On the basis of several embodiments shown in the drawing, the subject of the invention will be described in more detail below ' explained: Ea show

009831/0608

8AD ORIGINAL

■ PIiA 68/1279

Fig.l one with mechanical switches as an interruption switch

direction 'equipped diverter switch,' 2 shows one with controllable rectifiers as an interruption device equipped diverter switch,

3 shows a diverter switch according to FIG. 2, in which inductances are connected in series with the controllable rectifiers and the RC element is replaced by a capacitor, Fig. 4 one with mechanical switches as an interruption switch

direction equipped star point load switch, Fig.5 one with controllable 'rectifiers as an interruption fc - device equipped star point load switch.

Identical parts of the exemplary embodiments shown in the individual figures are marked with the same reference numerals, i. -

In Fig.l with 1 a part of the step winding of a step transformer is indicated. 2 and 3 are two selector contacts connected to the winding 'taps, each of which is connected to an alternating voltage pole of the GIe Lchrichtprbrücken 4 and ⁽ j) which are arranged in the course of the selector line and which consist of diodes 41, 42, 43, 44 and 51, 52 , 55, 54. In the DC branches of the rectifier bridges, switches 6 and ″ are connected in series with inductors 8 and 9 and the negative poles of the switches are connected via resistor 10 and capacitor II (RC-Gliod) The two other AC voltage poles of the rectifier bridges are connected to the outgoing load line 12.

In the basic position of the diverter switch shown in FIG the load current flows through the. connected to a winding tap Selector arm 2 and the rectifier bridge 4 to the load line 12. During the positive half-wave, the current takes its path via the diode 41, the switch 6, the inductance 8 and the diode 44, during the negative half-cycle via the diode 43, the switch 6, the inductance 8 and the diode 42.

If the transformer voltage is to be switched over, the selector contact 3 that is not carrying current is connected to the next

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most winding tap of the step transformer connected. "Thereupon the capacitor 11 charges via the switch 6, the Inductance 9 and the diode 51 on the difference voltage of the two winding taps. After that the real Switching process initiated by opening switch 6. , The switch 7 mechanically coupled to the switch 6 begins simultaneously with the closing movement. After def contact separation Ajn switch 6, the load current initially flows via an arc continue until the contacts of switch 7 touch. This switches on the other selector line and closes the discharge circuit for the RG element. By the beginning Discharge, the arc is immediately extinguished at switch 6 and that between the two winding taps The rise in the short-circuit current that occurs is interrupted, the steepness of the rise in the short-circuit current being able to be influenced by short-circuit chokes connected to the selector lines. When the arc is extinguished, the load current commutates to the other selector line and the conversion process is ended. If a switching process takes place during or shortly before a load current zero crossing, the inductance 8 holds the arc upright so that the load current * continues to flow after the zero crossing can until the other switch has closed.

Tn Fig.2 are - instead of the switches 6 and 7 and the inductors 8 and 9 only controllable rectifiers 60 and 70 as an interruption device in the direct current branches of the rectifier bridges switched. If one assumes, for example, that the rectifier 60 is continuously supplied with ignition pulses and this thus carries the load current, then fulfills the Circuit after the Pig.2 the same puncture as the circuit to Tig.l.

The actual switchover process is carried out by switching over the Ignition pulses to the rectifier 70 reached. This in turn switches on the other selector line and the discharge current circuit closed for the capacitor of the RC element 10, 11. When the discharge starts, the rectifier 60 is blocked and the load current commutates to the others

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009-841 / 060-8, .-.

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PLA 68/1279

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Voter management. As a result of the rectifier's immediate blocking 60 when the rectifier 70 is fired, the short-circuit current becomes between the two winding taps again interrupted in its rise phase. - '

In Fig.3 are in the DC branches of the rectifier bridges 4 and 5 the inductors 80 and 90 with the controllable rectifiers 60 and 70 connected in series. The RC element is 10.11 replaced by a capacitor "110.

Assume again that rectifier 60 is fired ". Thus, the inductor 80 holds during the load current zero through -P gear in the direct current branch of the rectifier bridge 4 a certain-current flow upright, so that the natural blocking of the rectifier 60 prevented and the continuous ignition pulse delivery after each half-wave is superfluous. A switching process is initiated by a single ignition pulse being sent to the rectifier 70. By firing the rectifier 70 the 'discharge circuit for the capacitor 110 is closed and by the discharge current on the inductance 80 a voltage built up, which blocks the rectifier 60, so that the load current commutates to the other selector line.

In FIG. 4, the rectifier bridges 40 and 50 are expanded by the diodes 45, 46, 47, 48 and 55, 56, 57, 58, respectively. Because of the star- W point-side arrangement of the winding taps, the corresponding selector lines can each be connected to an alternating current connection of the rectifier bridges extended for the three-phase connection. The fourth AC voltage connections of both rectifier bridges are connected to the midpoint line 13. The negative poles and the positive poles of the rectifier bridges are connected to one another by the same RD elements 10, 11 and 14, 15. As soon as the selector contacts 3 which are not carrying current are connected to the winding taps, the capacitors 11 and 15 are charged via the closed switch 6 with opposite polarity to the peak value of the step voltage. The appears at the open switch 7.

double step voltage.

PLA 68/1279

With the star point-side arrangement of the circuit breaker according to the invention, the inductances in the direct current branches can the GIeiehri.chterbrücken do not apply, since a multi-phase Rectifier bridge in the direct current branch no zero crossing of the load current occurs.

In Figure _5% of the rectifier bridges are connected 40 and 50, the controllable rectifier 60 and 70 to the inductors 800 and 900 in series in the DC current branches. Compared to the arrangement shown in FIG. 4, the RC elements have been replaced by capacitors 110 and 115. The mode of operation of the arrangement is in principle the same as in the case of the arrangement according to FIG.

The inductors 800 and 900 serve together with the 'capacitors 110 and 150 for generating the reverse voltage for the controllable which is forcibly canceled during a switching process Rectifier, the task of maintaining a certain current flow during the load current zero crossing in a There is no phase in the multi-phase bridge circuit.

The additional connection of the positive poles of the rectifier bridges 40 and 50 via a capacitor 150 leads to an increase in the reverse voltage at the controllable rectifier which cancels out. With the higher reverse voltage there is better commutation achieved.

10 claims
5 figures

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009831/0608

Claims (1)

PLA 68/1279 -12 claims (1. / arrangement for load switching with step transformers or - throttling, in which the outgoing consumer line is connected to the two selector lines via a switching device, is connected, characterized in that as peeling devices uncontrolled rectifier bridges (4,5) provided, aina, in their direct current branches at least * one mechanical each Switch (6,7) ". Is connected in series with an inductance (8,9), and. That the negative poles of the in between the two switching devices mechanical switch (6,7) via an RC element (10,11) ■ are connected (Fig.1). 2. Arrangement for load switching in step transformers or chokes in which the outgoing consumer line is connected to the two selector lines via a switching device, characterized in that uncontrolled rectifier bridges (4, 5) are provided as switching devices, in their Gieiehotromzweig at least one controllable rectifier (60,70) each is arranged and that the negative poles dpr in the Gl ei chatromzweig of both switching devices arranged controllable rectifier (60,70) via an RC-Gxied (10,11; connected oind (Fig. 2) . ^v . Arrangement for load switching for star point-side connection to step transformers or chokes, in which the cum Vcrrauchf τ- leading star point line is connected to the corresponding selector lines of all phases via switching device ^, characterized in that two multi-phase, uncontrolled rectifier bridges (40, 50) are provided as switching devices are, in whose direct current branches at least one mechanical switch (6,7) is arranged, and that the negative poles of the mechanical switches arranged in the direct current branches of both polyphase rectifier bridges (40,50) via an RC element (10,11) are connected to each other (Fig. 4) - 13 - 009831/0608 BATH ORIGINAL PLA 68/1279 • - 13 - 4. Arrangement according to claim 3, characterized in that the mechanical switch by controllable rectifier (60,70) are replaced. 5. Arrangement according to claim 2, characterized by inductances (80.90) between the negative poles of the controllable rectifier (60,70) and the negative poles of the direct current branches. 6. Arrangement according to claim 5, characterized in that the RC element between the negative poles of the controllable rectifier is replaced by a capacitor (110) (Fig.3). 7. Arrangement according to claim 2 or 4, characterized by mutual Ignition of the controllable rectifier (60,70) with different ignition pulse sequences. 8. Arrangement according to claim 3, characterized by an additional RC element (14,13) between the positive poles of the rectifier bridges (40.50) (Fig. 4). · ■ 9. Arrangement according to claim 4, characterized in that inductivities between the negative poles of the controllable rectifier (60,70) and the negative poles of the direct current branches (800,900) and the negative poles of the rectifiers (60,70) connected via a capacitor (110) are. 10. Arrangement according to claim 9, characterized by an additional Capacitor (150) between the positive poles of the rectifier bridges (40, 50) (Fig, 5). 009831/0608 ; BATH ORIGINAL