DE1929551A1 - High-voltage disconnector with upstream resistors - Google Patents

Description

The invention relates to a high-voltage disconnector Pre-switched resistors in the circuit when the switch is closed.

Voltage surges of relatively high magnitude can be generated when a circuit breaker is used to reclose a transmission line is closed. One known technique for reducing the magnitude of such surges is to a resistor of suitably low resistance during the closing process in the circuit immediately before to be inserted at the moment when the main contacts engage. For example, reference is made to the US patent 3 291 94-7 or to the publication by Hedman et al with the Title "Switching of JüHV Circuits, II - Surge Reduction with Circuit Breaker Resistors "in IBEE Transactions on Power Apparatus and Systems, December 1964, p. 1196-12o5.

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The disconnectors described in these references typically contain main interruption lines switched in Heine and for each main interruption line a "closing resistor ¹¹ " which is switched on in parallel to the interruption line immediately before the main contacts of the interruption point come into engagement in the circuit. It is possible by selecting a suitable resistance value to limit the ratio of the peak voltage surge value between the line and ground when closing to about 2.0 per unit under most switching conditions. In some applications, however, this value is still zn high.

It is an aim of the present invention to limit this peak value of the surge voltage when closing or closing again to a value which is significantly lower than the value achievable by the previously known arrangements with the addition of resistors, since awf tmni ^ less than about 1.7 per unit under most side aging conditions.

In one embodiment of the arfindiaiag, a Mochspamrangs is Isolating switch provided for opening and closing the circuit via a power transmission line. Of the Disconnector comprises a plurality of pairs of main contacts connected in none. The contacts of every couple are separable from each other to during the separation of the Circuit to adjust a distance between them, jss is-fc an automatic reclosing device is provided, which within 4-0 electrical periods after opening the Bringing main contacts back into engagement. The pairs of Main contacts are each assigned to resistor snifcfcel «, üa first switching device can be operated so that at least part of the resistance means during a re-closing process before the in engagement kosamen

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Main contacts are switched via the associated spacing. This results in a first predetermined effective value of the resistance, which is parallel to these racing distances · A second "switching device is provided to then begin the parallel to these 'i' racetracks effective resistance during a later part of the closing process before re-engaging the Reduce main contacts,

The figures and the following description serve to provide a better understanding of the invention.

Fig. 1 is a schematic side view of a circuit breaker an embodiment of the invention.

Fig.1a is a schematic view showing more details of the circuit breaker according to Fig. 1 shows.

Fig. 2 is a schematic illustration of the operating mechanism for the auxiliary resistance switches which can be used in the circuit breaker of FIG.

Fig. 3 is a schematic representation of a modified embodiment of the invention.

Figure 4- is a schematic representation of another Embodiments of the invention.

The preferred embodiments of the invention are as follows described. Fig. 1 shows a high-voltage circuit breaker 10 with a few arrangements 12 and 14 for Control of the circuit. Each arrangement 12,14- for controlling the circuit comprises a metal container 20, which is at a high voltage with respect to ground and a high insulation column 17, which carries the container 20 and him

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isolated from earth. Each of the * Isölation columns 17 attached to a suitable frame (not shown). The arrangements 12 and 14 for controlling the circuit are in one of the phases or lines 15 of a high-voltage alternating voltage circuit electrically connected in series with one another.

A circuit drawing in the schematic representation of FIG. 1 shows the components of the arrangement 12 or 14 for Control of the circuit which is inside the high-voltage container 20 are arranged. Inside each container 20 there are two connected in series Pairs 22 and 24 of relatively movable main contacts. Each pair 22, 24 of main contacts includes one fixed contact 25 and a movable contact 26. The two fixed contacts 25 are each held by an Anöchlußhülse 28, which through opposite ends of the metal container 20 through. These sleeves comprise conductive inserts 29 as a power supply line the fixed contacts 25 and tubular insulators 30 for Isolation of the conductor parts 29 and the fixed contacts 25 from the tank 20 when the circuit breaker is open.

Shunted to each pair 22, 24 of main contacts 25, 26 is a series circuit of a main resistor 32 and a main resistor switch 34. Der Main resistance switch 34 has a fixed contact 36 and a moving contact 37 · If the resistors 32 connected via the main contacts 22 and 24 .sind are used they regulate the speed at which the voltage changes during the interruption of the circuit builds up over the main contacts and they also regulate the size of the surge voltage, which is applied to the isolating switch when skiing occurs. .

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For this latter control function, each resistance switch be closed slightly before the main contacts to which it is shunted. Additionally the resistance switches in the two arrangements must be essentially simultaneous to control the circuit closed to allow for a breakdown of the insulation parallel to the last closed switch to reduce. In this regard, certain circuit breakers require that all resistance switches 34 during a closing process within a period of time make contact of about 2 milliseconds. In the US patent 3,333,071 devices are shown and claimed to be this essentially simultaneous closing of the resistance switches at a time prior to the engagement of the main contacts to effect, and such devices can can be used in the circuit breaker according to the invention.

By choosing suitable values for the resistors 32 is it is possible, under most switching conditions, to measure the peak value of the surge voltage between the line and ground Limit closing to a maximum of about 2.0 per unit. However, this is still too high for some applications. As already As stated above, the aim of the invention is to limit this peak value of the surge voltage on closing to a considerably lower value, i. H. to 1.7 per unit.

In the embodiment of the invention of Fig. 1, this object is achieved in that over each pair of main contacts two different values of resistances at different times during the closing process before the engagement the main contacts are switched on. The second resistance is considerably lower than the first Resistance. Specifically, be at least 24-0 electrical degrees at a time prior to engaging the

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Main contacts the resistance switches 34 essentially closed at the same time in order to switch the resistors 32 via the respective separation points 22, 24, 22, 24. to at a point in time at least 120 electrical degrees later, another set of resistance switches 40 is closed, to auxiliary resistors 42 across the main disconnection points 22 parallel to the main resistors that have already been switched on 32 to switch. According to this, the value of the resistance across each separation point is equal to the effective resistance the parallel combination of resistors 42 and 32, which is lower than the value of the originally switched on resistor. Bs was found to be this Resistance reduction following the original presetting of a resistor and before the the main contacts make it possible to reduce the peak value of the surge voltage considerably in comparison with the without the interposed Widerstaiadswsri®- peak value of the impact chipmiag *

In-depth studies with analog computers and carried out with numeric calculators * to find the optimal resistance values for the two resistors 32 and 42 to find which is the peak value when closing or closing again of the voltage surge at the lowest value. On the basis of these computer examinations, it appears that the effective total value of the resistor switched on first 32 about 2.2 to 3.3 times the impedance of the transmission line compared to a voltage surge should be · = te. The effective total value of the resistance over the " Separation points 22 and 24 after closing the switches for the auxiliary resistors should be about 0.4 to 0.8 times © this impedance for the voltage surge. For a typical circuit breaker for 765 & v «ad assuming- ^ that it is suitable for a circuit with an impedance of 36 © Ohms used for a voltage surge seem Si ©

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optimal effective resistances for the first stage to be around 1000 ohms and for the second stage around 200 ohms. The effective resistance of 200 ohms in the second stage is achieved by using resistors 4-2 with a total resistance of 250 ohms. The main resistors 32 can ^ eder the same size, and in this particular embodiment has $ & ά.βτ a resistance of 250 ohms. The auxiliary resistors 42 can also be of the same value, and in this particular embodiment each had a resistance of 62.5 ohms. The investigations on the electronic computer indicate that a circuit breaker equipped with such resistors limits the voltage surge between the transmission line and ground to about 1.6 per unit when closing or reclosing a circuit which has the assumed impedance to voltage surges.

It is important that at least a time corresponding to 120 electrical degree between successive stages the closing process of the circuit breaker can elapse, d. a. between the insertion of the resistor 32 and the Insertion of the resistor 42 and between the insertion of the resistor 42 and the closing of the main contacts. The reason for this is that ^ e & er step creates voltage surges, which tend to persist. If there is not enough time to absorb these shocks, then one impact is superimposed on the other and one obtains even higher total stresses. By taking a time from 120 degrees elapse between successive steps, sufficient damping takes place to prevent this mostly avoid iroblem ze.

One type of switching operation that can be particularly harsh from the standpoint of generating high voltage surges is that Connect to a transmission line on which there is

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trapped cargoes. This situation is usually encountered with automatically closing Disconnectors, which typically close again within 40 electrical periods after a disconnection process and in some years a shorter one Time. In dry weather, the captured cargo can be transferred to an interrupted transmission line Maintain a value a few percent below its original value for a second or longer. Hence, essentially the full trapped charge can be present on a healthy transmission line, when the circuit breaker closes again. As is known, the presence of this charge increases the size of the Closing generated switching shocks. By the invention However, arrangement to pre-insert resistors can still limit the maximum voltage surge between line and reclosing mass can be limited to less than 1.7 per unit despite the trapped charge.

another type of switching operation is closing or Reclosing of transmission lines which are compensated by a shunt inductor. the Interaction of the shunt reactor and the capacitance of the transmission line leads to voltage oscillation on the transmission line, typically between 30 and 58 Hz when the line is de-energized. Through the The arrangement according to the invention can measure the maximum value of the voltage surge between line and ground when reclosing such a transmission line with compensation by shunt reactor to less than 1.7 per Unit can be reduced. .

It should be noted that the invention in its more comprehensive Aspects is also applicable to disconnectors, which

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allow slightly higher peak values of the voltage surge, although the inventive arrangement has the capability has to limit this voltage value at closing or reclosing to 1.7 per unit.

The present circuit breaker is a circuit breaker with automatic reclosing and therefore contains devices indicated schematically at 46 in FIG. 1 a Forcing the disconnector to close again within 40 periods after opening. The device for Generation of the automatic reclosing can be a suitable conventional device known per se, how they z. As described in US Patejit 2,582,027, and their details are / are not shown. The fig. 1 a shows in schematic form the control unit 46 for reclosing, which the unit 47 for closing drives. The unit 47 for closing controls directly the resistance switch as shown in Fig. 1 a. The main separation routes are separated by a 48 designated control unit controlled, which at a predetermined Time in the closing cycle of the resistance switch is triggered.

To avoid unnecessary complication of the drawing and description, the details of the Operating mechanism for the auxiliary resistance switches 40 not shown, which is not the subject of the invention belong. However, Fig. 2 shows a sctiematic diagram a suitable operating mechanism for the auxiliary resistance switches 40 in each container 20. This mechanism Hmfasst a piston 50, which with the movable contact arms 45 of the auxiliary resistance switch 40 is coupled and an opening spring 52, which the contact arms in the open Holds position. A normally closed control valve 54 controls the movement of the piston 50. This

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Control valve normally forms a drain valve for the Barely 55 above piston 5Q. At a predetermined At point in the shutdown cycle of the circuit breaker, control valve 54- is opened to provide a Supply gas pressure and the contact arms 4-5 in the closed To move position. As soon as the associated main contacts 26 reach the closed position, the valve 54- through suitable devices for ventilation of the space 55 is closed again and thus the reopening of the auxiliary resistance switches is under the influence the opening spring 52 possible. Hence the auxiliary resistors immediately after the main contacts 26 are closed and before the main contacts are reopened from the Circuit removed.

By opening the resistance switch 40 if the main contacts 22, 24- are closed, there will be no need eliminated that the resistance switches have the properties of a breaker. In particular lead the resistors 4-2, since the main contacts 22, 24- closed are if the opening of the resistance switch 40 is triggered, then no current and therefore flows in their Opening no flow through the resistance switch 4O. The time during which the resistors 4-2 carry current can also be used must, and their required heat capacity are limited by the fact that these insert resistors 4-2 only during of closing can be inserted into the circuit.

In a modified embodiment of the invention, the resistance switches 34- before the main contacts are opened 22, 24 - brought to open during the opening cycle of the circuit breaker and the opening of the resistance switch 40 until a time after opening the main con *, bars 22, 24 delayed. This causes the resistance

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42 is the opening resistance. This means that there is a lower resistance when opening and that therefore, the build-up of the voltage across the main contacts 22, 24 then takes place at a slower rate.

Although FIG. 1 shows only one auxiliary resistor 42, which is parallel to each main line schalftar, of course, additional auxiliary resistors can unrefined gradual reduction may be provided for parallel connection with demHauptwiderstand, allow the ¹ resistance during the course of the closing process to. This more gradual decrease in resistance allows further reductions in surge voltage to be achieved. However, these reductions appear to be of relatively minor magnitude and therefore a single intermediate stage for drag reduction as shown in Figure 1 is preferred.

Fig. 3 is a schematic representation of another Embodiment of the invention. This embodiment includes Main contacts 22, 24, main closing resistors 32 and Main resistance switch 34 of substantially the same Form and mode of operation as in Fig. 1. These individual parts are therefore given the same reference numerals as the corresponding ones Parts in Fig. 1 designated.

In the embodiment of FIG. 3, the reduced Resistance achieved during the second stage of the closing process in that a part of each of the main resistances 32 is short-circuited. This is done by means of a series of auxiliary switches 50, each of which has a contact 52, which is connected to an intermediate tap point 53 on the resistor 32. The other contact 54 is connected via a line 56 to a point 57 between the adjacent resistors 32.

When each auxiliary switch 50 closes, it closes

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a part of the associated resistor 32 short and reduced thus the effective resistance across the main contacts 22 or 24 to the resistance of the non-shorted part of the resistor. This circuit arrangement can be used to have the same effective resistance across each main breakpoint as in Fig. 1 and give the same length of time between the individual switching steps.

The same mechanism as shown schematically in FIG can also be used to operate the auxiliary resistance switch 50 can be used. This opening mechanism opens the auxiliary resistance switch 50 immediately afterwards which the main contacts close. So that the auxiliary resistance switch 50 does not take on the following in the same way Opening process part like the auxiliary resistor 42 of FIG. 1.

If it is to be noted that with the arrangement according to Fig. 3 may also receive additional steps to achieve a more gradual drag reduction. The dashed lines indicate how to do these additional steps could achieve. In particular, each resistor 32 be provided with an additional tap and an additional auxiliary switch 60 to this additional tap to be switched on after a suitable time after switching on the first tap. Closing the additional Auxiliary switch 6ü short-circuits another part of the resistor 32 and thus further reduces the effective resistance above the main barrier.

Fig. 4 is a schematic representation of another Embodiment of the invention. There is only one resistor 32 and one resistor switch 34 here connected in parallel to each main separation point. In this

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Arrangement are essentially all resistance switches 34 during the closing process of a circuit breaker closed at the same time at least 24 ° electrical degrees before the time at which all Main stations 22, 24- are closed. With this arrangement However, the main separation points are not essentially simultaneous, as in the other arrangement of the ! • 'all is closed. First are the main separation points 22, 24 of the arrangement / closed to control the circuit. Then, at least 12u electrical degrees later, the main breakpoints 22, 24 of the assembly 14 become control the circuit closed. The closing of the main disconnection points of the first arrangement 12 for controlling the circuit, while the main extremities of the other arrangement 14 are still are open, has the effect that the resistors 32 of the arrangement 12 are short-circuited, while the resistors 32 of the other assembly 14 in series with the power transmission line 15 lie. Assuming that the resistors 32 have the same size, this means that the preset resistance is reduced to half of its original value. Be at least 120 ° after that the main separation points 22, 24 of the arrangement 14 are closed and thus short-circuited the remaining resistors and the closing process is completed.

In a typical 500 kV circuit breaker, there are resistors with a total resistance value approximately equal to half the impedance of the transmission line against voltage surges. In the second switching step this becomes Resistance reduced to half its value. In this particular arrangement, the resistors each have one Resistance value of 100 ohms.

The arrangement of Fig. 4 is simpler than the other arrangements, because it has fewer resistors and resistance switches. But it has the disadvantage that one of the

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ordinances 14 to control the circuit of the entire
Voltage across the circuit breaker is suspended during
the period in which its main separation points are still open and the main separation points of the other arrangement 12 are closed. This is usually permissible
if only two arrangements for controlling the circuit are connected in series, as in Fig. 4, then each must anyway be designed so that it can withstand at least half of the full voltage. However, if more than "two circuit control arrangements are connected in series, then each individual circuit control arrangement is usually for lesser ones
Constructed tensions and cannot apply the
withstand full tension.

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Claims (1)

- 15 -PATENT CLAIMS High-voltage disconnector for opening and closing again es circuit in a transmission line for alternating current, characterized in that they have a plurality of series-connected pairs of main contacts (22, 24), the contacts (25, 26) each Pair (22, 24) separable from one another to open a separation distance between the contacts during the process the interruption of the circuit, a device (46) for re-engaging these main contacts (25, 26) within 40 electrical periods after the opening process, resistance means (32, 42), each of these Pairs (22, 24) of main contacts (25, 26) are assigned, a first switching device (34) for connection at least part of these resistance devices (32, 42) the associated separation distances between the contacts (25, 26) during the closing process before reengagement come these main contacts (25, 26), whereby a first predetermined, effective resistance value is parallel to these Isolating distances results, and a second switching device (40) for the subsequent reduction of the effective resistance lying parallel to the isolating distances to predetermined ones Second resistance values come during a later part of the locking process before the main contacts engage (25, 26), these first and second resistance values being of such a size that they pass through consistently limit line-to-ground peaks caused by closure to less than 2.0 per unit. Isolating switch according to claim 1, characterized in that the first and the second Resistance value (32, 42) have such a size that they consistently on the peak value of the voltage surge generated by the closing between line and ground limit less than 1.7 per unit. 909881/0992 3. Isolating switch according to claim 1, characterized in that it is a control device has for actuating the second switching device (40) ' at a time of at least 120 electrical degrees after actuation of the first switching device (34) during of the closing process and at least 120 ° before the associated main contacts (25, 26) come into engagement again. 4. Isolating switch according to claim 1, characterized in that S ^e "" indicates that the total resistance, which by actuation of the first switching device (34) on the fc main contacts are switched between the 2.2 and the 3.3 times the impedance value of the current-carrying line against voltage surges and that when actuated the second switching device (40) via the main contacts (25, 26) switched total resistance between 0.4 and 0.8 times the value of the impedance of the live line against voltage surges. 5. Isolating switch according to claim 1, characterized in that each of the resistance devices (32, 42) has a first resistor (32) and one second resistor (42) which can be connected in parallel to the associated pair (22, 24) of main contacts (25, 26) ) are, and that the first resistor (32) by actuating the first switching device (34) above the associated pair (22, 24) can be switched by main contacts (25, 26) and that the second switching device (40) is such that it during the last part of the closing process the second resistor (42) parallel to the first resistor (32) via the associated pair (22, 24) of the main contacts (25, 26) switches. 6. Isolating switch according to claim 1, characterized in that the resistance device (32) and the second switching device (40) are such that the circuit has a reduced effective Has resistance by means of a short circuit of part of the resistance device (32), which by the first 909881/0992 '' Switching device (34) parallel to the main contacts (25, 26) is connected by a short circuit across the second switching device (40). 7. High-voltage disconnector for opening and closing the circuit in a transmission line for alternating current, characterized in that it is a Having a plurality of pairs (22, 24) of main contacts connected in series, the contacts (25, 26) each pair can be separated to create an isolating distance between the contacts while the circuit is being opened, that they have a re-engagement device (26) to re-engage bring the main contacts within 40 electrical periods after the opening process of each of these pairs of Resistance devices associated with main contacts (32, 42) and switching devices (34, 40) for connecting at least a portion of the resistance devices via the associated ones Separation distances between the contacts during a closing process before the main contacts re-engage whereby the circuit has a first effective resistance value in series with the current-carrying line, and that they have a device (40, 42) for the subsequent reduction of the effective value of the resistance in Row, with the current-carrying line during a later part of the closing process and a device that ensures that the decrease in effective resistance was consistently more than 120 electrical degrees before All main contacts come into engagement again and more than 120 electrical degrees after switching on the first resistor (32) enters in series with the line, the first and second resistance values being one Have size that they the peak value of the voltage surge caused by the closing between line and limit mass to less than 2.0 per unit. 9 09881/0 992 -.18 - .8th. Isolating switch according to Claim 7, characterized in that the first and second resistance values (32, 42) are of such a size that they the peak value of the voltage surge between line and ground caused by the closing to less than 1.7 per Limit unity. 9. Isolating switch according to claim 7, characterized in that it has a device for ■ Close some of the main contacts more than 120 degrees the closing of the remaining main contacts, and the * effective resistance value is reduced by the fact that the is short-circuited parallel to the first closed contacts and the circuit has the resistance above the contacts that are still open. ι 10. Isolation switch according to claim 7, characterized in that it has a device (54) for short-circuiting a portion of the resistor (32) connected across each pair of main contacts for reduction , the effective resistance. 11. Isolating switch according to claim 7, characterized in that it is a switching device and a resistor connected by this device in parallel with the resistor already connected via the main contacts Has a reduction in the effective resistance. 909881/0992 Blank page