DE202016007195U1 - Current-limiting switching device - Google Patents

Abstract

Current-limiting switching device with at least two parallel-connected current paths, of which one current path opening in the current increase and controllable by a measuring and tripping device (4) electrodynamically acting rapid switch (1) and another current path has a resistor (26) as a current-limiting electrical component, wherein in series with the parallel-connected current paths an interruption switch is connected, characterized in that in series with the resistor (26) at least one further resistor (27, 28) is connected, which by a parallel thereto and by the measuring and tripping device (4 ) controllable semiconductor switch (29, 30) is effectively or ineffective switchable and that the breaker switch is designed as a after the current limit also by the measuring and tripping device (4) controllable power switch (3).

Description

The invention relates to a current-limiting switching device with at least two parallel-connected current paths, of which one current path has a current-rising and controllable by a measuring and triggering device electrodynamically acting rapid switch and another current path has a resistance as a current-limiting electrical component, in series with the parallel Current paths, a breaker is engaged.

Switching devices of this type are intended to prevent damage in systems of electrical power distribution by high fault currents, in particular short-circuit currents. Such high currents, which are many times higher than the normal operating current of the systems, cause both high mechanical and thermal stresses on the components of the switchgear, which can lead to the destruction of system components and endanger occupationally or accidentally present persons.

The principle of a switching device of the type considered is the EP 1 022 753 B1 refer to. The electrodynamic high-speed switch is a Thomson system connected in parallel to the two commutation paths. Of these, the one includes a PTC resistor which is bypassed at the beginning of a fault shutdown by a semiconductor switch in series with a contact-type switch. Thus, the effect of the resistor begins delayed.

Although the said switching device is constructed using components that are in principle suitable for a significant number of switching cycles and therefore are functional again after an error shutdown without repair or repair, could EP 1 022 753 based switching devices can not find an input in power installations.

Rather, due to the consideration, the limitation of short-circuit currents with the most robust and reliable acting, but at the same time relatively inexpensive components, the way has been taken to use a high-speed circuit breaker and to effect current limiting by current-limiting fuses, which at the same time the faulty circuit completely interrupt. This combination is called Is-limiter in the DEABB 2493 14 de from ABB AG Calor Emag Mittelspannungsprodukte, 2014 described.

The blasting separator, z. B. after DE 1 102 892 A , is a fully enclosed device containing a conductor to be broken by an explosive charge. The explosive charge is ignited by the tripping device and interrupts the conductor within a very short time by destruction or deformation. Due to this interruption of the switching path, the current now flows through the fuse arranged parallel to the switching path. The resulting after melting of the fusible conductor arc is strongly cooled by a sand filling of the fuse housing, which leads to an increase in the arc voltage. Thus, a corresponding increase in the resistance of the current path and a strong attenuation of the fault or short-circuit current is connected to the interruption. To increase the switching capacity, it is known in this context to connect several fuses in parallel.

Due to the two operations described, interruption of the current path in the explosive separator and response of the fuse, the switching device is no longer functional after a fault trip, so is no longer available as protection for another error and must be replaced or repaired. In particular, the repair, due to the explosive separator, only by the manufacturer of the switching device is possible. For the operator of a switchgear thus creates a not inconsiderable expense, if after a serious fault in the network or in the switchgear the previous state, d. H. the protective effect against such errors, should be restored. In order to ensure the protection of the system during the repair of the isolator, it is necessary to install a replacement unit.

Similarly, the repair after a shutdown requires the current-limiting switching device, which under the name FC Protector in the Publication DEABB 2554 16 de from ABB AG Calor Emag Mittelspannungsprodukte, 2016 , is described.

On this basis, the invention is based on the object of providing a permanent and largely maintenance-free current-limiting switching device which contains as few and robust components as possible.

According to the invention, this is achieved in that at least one further resistor is connected in series with the resistor, which is connected by a semiconductor switch (parallel to it and controllable by the measuring and tripping device). 29 . 30 ) is effective or ineffective switchable and that the breaker switch as a after the current limit also by the measuring and Triggering device ( 4 ) controllable circuit breaker ( 3 ) is trained.

In the switching device according to the invention, the current-limiting resistor at the opening of the electro-dynamic high-speed switch is effective immediately and without delay. The series connection of this resistor with at least one further resistor with parallel semiconductor switch causes a delayed increase in the resistance value and therefore increased current limit.

Essential for the invention is a current limiting only to the extent that a normal circuit breaker is able to interrupt the remaining power. This has the consequence that lower demands are placed on the current-limiting resistors and beyond an additional semiconductor switch, as in the current-limiting switch after the EP 1 022 753 B1 or De EP 1 104 403 A1 is provided, is not needed.

In itself it is through the DE 0 862 470 C It is known that the resistance value of a current limiter does not have to be so high that the faulty circuit is interrupted because, for example, an arc fault extinguishes already at a certain finite limit value of the current. To interrupt the circuit should therefore after said DE 0 862 470 C serve a circuit breaker. However, the switching capacity of disconnectors is limited to relatively low values. If, in contrast, as the invention provides, a circuit breaker is used, the requirements for the current-limiting resistor substantially decrease with a corresponding advantage for the size of the resistance units.

The mentioned circuit breaker is a common device in medium voltage switchgear and z. B. be a vacuum circuit breaker. Essential in the present context is the delivery of a directed to the circuit breaker OFF command by the measuring and tripping device to completely interrupt the circuit after the current limit. Thus, the circuit breaker does not work as a stand-alone protection device, but in a well-coordinated sequence with the previous current limit.

In the context of the invention, the resistors may be formed by a respective resistance unit having an approximately cuboid, provided with bushings housing made of an insulating material, a filling with an insulating liquid and a resistor conductor embedded therein and supported. As an insulating liquid is particularly suitable an ester liquid, as used for example in transformers. Esters have, in addition to similar good electrical and thermal properties as the previously used insulating oils and PCB fluids, beneficial environmental properties such as nontoxicity and oxidation resistance. Details are z. B. the Publication "Midel 7131 - Synthetic Ester Transformer Fluid - Technical Documentation - June 2016" to be taken from the Midel Library at the Internet address http://www.midel.com/de/library is to download.

The resistor ladder may be of considerable length to provide the required resistance while maintaining high current carrying capacity. According to one embodiment of the invention, a small amount of space can be achieved in that the resistance conductor is meander-shaped and arranged in planes that lie at an angle to one another in such a way that there is an increased distance between locations of increased voltage stress.

A meander-shaped arrangement of a resistance ladder is known and in the present context z. B. in the EP 1 014 403 A1 shown.

There, however, a cylindrical housing is provided, which complicates the placement in a switchgear.

As a semiconductor switching element IGBT (Insulated Gate Bipolar Transistor) are suitable due to their dielectric strength and their current carrying capacity. These components are available in a non-applied control signal conductive design ("normal-conductive"), which is advantageous for the present purpose.

For the application of the current-limiting switching device according to the invention, it proves to be advantageous if ever an electrodynamic quick switch for each phase of a three-phase network, three series resistance units per phase and associated controllable semiconductor or a semiconductor semiconductor block comprising this and a three-pole circuit breaker in a switchgear having three adjacent fields are arranged such that in a first field, the rapid-action switches, in an adjacent field, the resistance units and in the third field of the circuit breaker are arranged, the fields each having a low-voltage space and the measuring and tripping device in one of the low-voltage spaces or distributed over two or all of them.

The invention will be explained in more detail below with reference to exemplary embodiments.

The 1 schematically shows the essential components of a current-limiting switching device according to the invention in their circuit-related relationship, but without more design features.

The 2 and 3 show details of one in the 1 shown rapid switch 1 , in the closed position in the 2 and in the off position in the 3 ,

A graph in which the energy to be absorbed by the current limiter is plotted against time is shown in FIG 4 ,

The structure of a resistance unit, which has a resistance value corresponding to the resistances 26 . 27 and 28 show, the show 5 . 6 . 7 . 8th and 9 , This illustrates the 5 a meandering arrangement of a resistance ladder, while the 6 . 7 and 8th orthogonal views of a resistance unit and the 9 whose section shows.

A three-field switchgear as a current-limiting switching device including a circuit breaker shows the 10 , Side sections of the three fields are in the 11 . 12 and 15 shown. The 13 and 14 are cuts AB and AC of the in the 12 shown field, wherein the section AB for visualization of semiconductor units and the section AC is used to display below the semiconductor units located resistor units.

First, the basic structure of a switching device according to the invention with reference to 1 explained. Herein is emphasized by a greater line width of the essential for the invention current path. The representation is single-phase for simplicity. The circuit shown includes a quick switch 1 , one to this parallel current limiter 2 as well as a circuit breaker 3 , All of the above components are controlled by a measuring and triggering device 4 controlled.

The quick switch 1 works on the Thomson principle and is in the 1 simplified as an opening contact shown. The essential elements of the quick switch 1 will be described below on the basis of 2 and 3 explained. There is an electrodynamic drive device 5 a movable contact piece 6 shown in the rest position shown fixed sprung counter contact pieces 7 and 8th connects with each other. To the drive device 5 heard a coil 10 , which is an electrically conductive disc 11 or a ring facing and by means of a trained as a tubular hollow body shift rod 12 is arranged axially movable.

For the operation of the quick switch 1 is a control unit 13 provided, in a known manner, a capacitor bank as energy storage for feeding the coil 10 may contain. The release of the stored energy is carried out by a command of the measuring and tripping device 4 in the 1 by means of a dashed control path shown 14 , An example of a controller is the DE 28 00 076 C2 refer to.

In the course of the elimination is a compression spring 15 strained, on the one hand on one in the hollow shift rod 12 engaging penholder 16 and on the other hand, at the bottom of a housing 17 supported. To the movable contact piece 6 reliable in the off position according to 3 hold a pawl engages 18 about a lead 19 at the lower circumference of the shift rod 12 and snaps under the action of a tension spring 20 behind the projection 19 one. A reset device 21 is provided to the pawl 18 against the action of the tension spring 20 from the nose 19 to solve. The shift rod 12 with the contact piece 6 then returns under the action of the compression spring 15 in the starting position according to the 2 back. The reset device 21 has an actuating magnet 22 and a pestle 23 on, that of the pawl 18 against the action of the tension spring 20 around a pivot bearing 24 emotional. One of the measuring and tripping device 4 outgoing control path 25 causes the control of the actuating magnet 22 ,

As the 2 and 3 show are the electrodynamic drive device 5 and the cooperating components in the housing 17 accommodated. Here are the axial guidance of the movable contact piece 6 omitted components for ease of illustration, since they are familiar to those skilled in the art. For effective commutation of a fault current to the current limiter 2 This can be helped by the case 17 dense and filled with a quenching gas. As a further advantageous supplement, two or more pawls for securing the movable contact piece 6 be provided in the off position. An appropriate arrangement of projections may be suitably formed by a ring with a rectangular cross-section, as shown in the 2 and 3 is indicated.

As a further detail of the current-limiting switching device according to the invention is based on the 3 the structure of the in the 1 shown current limiter 2 explained. This includes according to the 1 three equal resistances 26 . 27 and 28 which are connected in series with each other. Parallel to the resistors 27 and 28 are in consideration of the requirements in an AC network two antiparallel controllable semiconductor switches 29 respectively. 30 switched by the measuring and tripping device 4 issued commands conductive or blocking switchable. To the semiconductor switches 29 and 30 enter the control commands through the control paths shown in dashed lines 31a and 31b , As controllable semiconductors are suitable for the purposes of the invention z. B. IGBT elements (Bipolar insulated gate transistors), which are available in a normal-conducting or normal-blocking design. Advantageous is the application of the normally-conductive design, as this ensures that at the beginning of a shutdown inevitably the resistance 26 is effective, and that the additional resistors 27 and 28 subsequently programmed can be switched on. This can be done at fixed intervals, which affects in the circuit to be disconnected as a gradually increasing resistance value. Likewise suitable are semiconductor switches of the type IGCT (Integrated Gate-Commutated Thyristor), which control particularly high forward currents.

To understand the requirements of the resistors 26 . 27 and 28 It should be noted that in a typical application for a short time, ie for about 90 ms, a voltage of 12 kV and a current of about 4400 A may occur. This stress can be controlled by a conventional resistance wire approx. 100 m long with a thickness of 4 mm. Calculations show that in this case an energy of P = 1.6, 0.9 and 0.7 MWs is to be included successively. This process is in the 4 illustrates, in which the gradual and staggered effect of the resistances 26 . 27 and 28 along the time axis t of the diagram can be seen.

The process of current limitation is in the 4 illustrated. At time t _a is only the resistance 26 effective as the further resistances 27 and 28 through the parallel semiconductor switches 29 respectively. 30 are bridged. Fuses no complete break in the circuit. The of the measuring and tripping device 4 issued commands now bring the semiconductor switches 29 and 30 one after the other into the blocking state. If the time t _{e is} reached, the circuit breaker interrupts 3 the circuit after coming off the measuring and tripping device 4 over the control path 31c has received a corresponding tripping order.

For the mentioned control paths, all known means for the transmission of analog or digital signals come into consideration, in particular wired, fiber-optic or radio-based systems. What is important is signal transmission that is as delay-free as possible, since in the present context it is important to initiate processes at a distance of a few microseconds and milliseconds. This applies in particular to the control path 14 to trigger the quick switch 1 and the subsequent activation of the semiconductor groups 29 and 30 in the sense of a circuit program.

Based on 5 to 9 Now a resistance unit is described, through which the resistors 26 . 27 and 28 obtained a suitable design for use in a switchgear design.

A small space requirement is achieved by a resistance ladder, z. B. at 33 beginning resistance wire 32 CuNi is formed in plane meanders, which are arranged in several levels at a mutual distance in a housing and at 34 again emerge from this. As the 5 shows, they run through their baselines 35 . 36 and 37 Marked planes not parallel, but at an angle to each other, such that at locations of increased stress increased distances 38 respectively. 39 result.

The design of a resistance unit 40 in which the arrangement according to 5 is recorded, is now based on the 6 . 7 8th and 9 described. A comparison of the side, front and top views shown therein shows that the resistance unit 40 a substantially cuboid housing 41 owns, which is divided approximately in the middle, whereby a lower part 42 and a top 43 each serving a tight connection flange 44 respectively. 45 have. Lockable filling and drainage nozzles 46 and 47 are provided to the housing 41 with an insulating liquid, in particular an ester liquid to fill or to empty the housing. The top 43 of the housing 41 carries bushings 48 and 49 for the connections of the resistor ladder 32 , As the top view according to the 8th shows, the bushings are approximately diagonal, ie arranged with the largest possible distance.

The housing 41 is in the 9 partly shown in section. There are holding bars in it 50 shown for positioning and securing the resistance ladder 32 serve. For the production of the housing 41 Insulating plastics such as epoxy casting resin or the like are particularly suitable. The intended division of the housing into a lower part 42 and a slightly equal top 43 allows a production of both parts in one piece, wherein the upper part of the bushings 48 and 49 can be integrated.

The following is based on the 10 to 15 the application of the invention in a switchgear 51 explains the three immediately adjacent fields 52 . 54 and 55 same size. This contains the field 52 the quick switch 1 according to the 1 . 2 and 3 , with regard to the application in three-phase current in three identical units arranged parallel to one another. The 11 is a side section of the field 52 and shows a cable entry from below, the quick switch 1 , as well as a busbar train 56 and to the neighboring field 53 leading executions 57 ,

In the side section according to the 12 it can be seen that in the middle panel 53 central about the semiconductor device according to the 1 is housed. This is for simplicity as a semiconductor block 58 thus having six antiparallel semiconductor combinations (two each for each of the three phases of the network). Below the semiconductor block 58 are at the bottom of the field 53 a total of nine resistance units 40 in three groups of three resistance units each 40 each phase. The cuts AB and AC the 12 are in the 13 and 14 represented and in particular leave the space-saving arrangement of the resistance units 40 due to their compact and substantially cuboid shape recognize. The small dimensions of the resistance units 40 are based in particular on the meandering shape of the resistance ladder and as a filling of the resistor housing 41 used ester liquid, which has a high insulating power and good cooling properties. The long-term resistance of ester fluids makes it possible to dispense with regular maintenance of the resistance units. These resistance units can remain permanently in the switchgear because they are not destroyed due to their design by a load with fault currents and thus need not be replaced.

The Indian 1 Circuit breaker shown as an end member of the switching device 3 can z. B. be a conventional vacuum circuit breaker, according to the 15 in the panel 54 is arranged. The output of the switching device is the cable outlet 59 ,

In a known way, each of the fields possesses 52 . 53 and 54 above a low-voltage room accessible from the front 60 , In one of these low-voltage rooms 60 or distributed over two or all may suitably the measuring and tripping device 4 ( 1 ), resulting in short paths for the control paths 14 . 25 such as 31a -C result.

LIST OF REFERENCE NUMBERS

1

Quick switch

2

current limiter

3

breakers

4

Measuring and tripping device

5

Electrodynamic drive device

6

Movable contact piece

7

Counter-contact

8th

Counter-contact

9

10

Coil of the drive device 5

11

Conductive washer or ring

12

shift rod

13

control unit

14

Control path for switching off

15

compression spring

16

penholder

17

casing

18

pawl

19

Projection on the shift rod 12

20

mainspring

21

Reset device

22

Actuating magnet of the return device 21

23

Plunger on the actuating magnet 22

24

Swivel bearing of the pawl 18

25

Tax path for provision

26

resistance

27

resistance

28

resistance

29

Semiconductor switch for resistance 27

30

Semiconductor switch for resistance 28

31

a control path for semiconductor switches 29 b Control path for semiconductor switches 30 c Control path for circuit breaker 3

32

resistor ladder

33

Beginning of the resistance ladder 32

34

End of the resistance ladder 32

35

Baseline of a ladder level 32

36

Baseline of a ladder level 32

37

Baseline of a ladder level 32

38

Increased distance between the baselines 35 and 36 ( 5 )

39

Increased distance between the baselines 36 and 37 ( 5 )

40

Resistance unit ( 6 . 7 8th . 9 )

41

Housing of the resistance unit 40

42

Lower part of the housing 41

43

Top part of the housing 41

44

Flange on the lower part 42

45

Flange on the upper part 43

46

Filler at the top 43

47

Drain on the lower part 42

48

Carrying on the upper part 43

49

Carrying on the upper part 43

50

Retaining bar in the housing 41

51

switchgear

52

Field (left) of the switchboard 51

53

Field (middle) of the switchgear 51

54

Field (right) of the switchgear 51

55

cable entry

56

the busbar

57

Passages between the fields 52 and 53

58

Semiconductor block

59

cable outlet

60

Low voltage compartment

QUOTES INCLUDE IN THE DESCRIPTION

This list of the documents listed by the applicant has been generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Cited patent literature

• EP 1022753 B1 [0003, 0012]
• EP 1022753 [0004]
• DE 1102892 A [0006]
• EP 1104403 A1 [0012]
• DE 0862470 C [0013, 0013]
• EP 1014403 A1 [0017]
• DE 2800076 C2 [0029]

Cited non-patent literature

• Publication DEABB 2493 14 of ABB AG Calor Emag Medium Voltage Products, 2014 [0005]
• Publication DEABB 2554 16 de from ABB AG Calor Emag Medium Voltage Products, 2016 [0008]
• Publication "Midel 7131 - Synthetic Ester Transformer Fluid - Technical Documentation - June 2016" [0015]
• http://www.midel.com/en/library [0015]

Claims (5)

Current-limiting switching device with at least two current paths connected in parallel, of which one current path opens one in the current increase and through a measuring and tripping device ( 4 ) controllable electrodynamically acting quick-acting switch ( 1 ) and another current path a resistor ( 26 ) as a current-limiting electrical component, wherein in series with the parallel-connected current paths an interruption switch is connected, characterized in that in series with the resistor ( 26 ) at least one other resistor ( 27 . 28 ) connected in parallel by and through the measuring and tripping device ( 4 ) controllable semiconductor switch ( 29 . 30 ) is effective or ineffective switchable and that the breaker switch as a after the current limit also by the measuring and tripping device ( 4 ) controllable circuit breaker ( 3 ) is trained. Current-limiting switching device according to claim 1, characterized in that the resistors ( 26 . 27 . 28 ) by a respective resistance unit ( 40 ) are formed, which is an approximately cuboid, with bushings ( 48 . 49 ) housing ( 41 ) of an insulating material, a filling with an insulating liquid and a resistor conductor embedded therein and supported ( 32 ) having. Current-limiting switching device according to one of the preceding claims, characterized in that the insulating liquid is an ester liquid. Current-limiting switching device according to claim 2 or 3, characterized in that the resistance conductor ( 32 ) meander-shaped and in angled planes (baselines 35 . 36 . 37 ) is arranged such that between locations of increased voltage stress an increased distance ( 39 . 40 ) consists. Current-limiting switching device according to one of the preceding claims, characterized in that each one electrodynamic high-speed switch ( 1 ) for each phase of a three-phase system, three series-connected resistance units ( 40 ) per phase and associated semiconductor switches ( 29 . 30 ) or a semiconductor switch ( 29 . 30 ) comprehensive semiconductor block ( 58 ) and a three-pole circuit breaker ( 3 ) in a three adjacent fields ( 52 . 53 . 54 ) are arranged such that in a first field ( 52 ) the quick switches ( 1 ), in an adjacent field ( 53 ) the resistance units ( 40 ) and in the third field ( 54 ) the circuit breaker ( 3 ), the fields ( 52 . 53 54 ) each have a low-voltage space ( 60 ) and the measuring and triggering device ( 4 ) in one of the low-voltage premises ( 60 ) or distributed over two or all of them.

Images