IL224639A - Explosive high speed self-restoring reusable ac fault current limiter - Google Patents

Description

EXPLOSIVE HIGH SPEED SELF-RESTORING REUSABLE AC FAULT CURRENT LIMITER FIELD OF THE INVENTION The present invention relates to the field of explosive devices to limit shortcircuit current in the AC. The aim of the invention is creating of high-speed low-cost current limiter, which provides the principal possibility of multiple operating of explosive device for automatic reboot of explosion charge and subsequent operation .without involved staff. The devices are intended for use in the circuit breakers.

BACKGROUIID OF THE INVENTION At present time it is known current limiting explosive network switches. The Company ABB widely uses explosive power switch, in which the switching element consists of a copper bus, connected in parallel with current-limiting fuse. In a case of short-circuit the copper bus is exploded (see ABB Power and productivity for a better world, ls-limiter, the world fastest limiting and switching device). This high speed and relatively inexpensive switch has a drawback - the need to replace the switching element after each operation and the inability to implement the automatic restart.

The company Siemens makes extensive use of breakers, in which the main contact is in normal mode, and in the process of extinguishing the arc special arcing contact is involved (Siemens, Power transmission and distribution, High-Voltage Circuit-Breakers 72.5 kV up to 550 kV 3AP 1/2). These switches process continues several periods (up to 80 ms), it does not limit the short-circuit currents.

Patent US 4,176,385 (Assignee Electric Power Research Institute, Inc.} describes the explosive multi-contact short-circuit current limiting breaker, which comprises a conductive portion of a cylindrical tube made of conductive metal (aluminum, copper, or other), surrounded by a number of rings from hard-alloy metal. The tube is filled with a dielectric material, such as paraffin. Explosion detonating cord is located in the dielectric along the tube. With the explosion the tube is breaks, forming a series of arcs, increasing the total voltage drop across the breaker. To increase the voltage drop across the arcs, thus limiting the total stress in the short-circuit; the number of the tube breaks should be significant.

Accordingly, the length of the tube should also be increased. On the other hand, since the rate of transmission of detonation wire for detonating is limited 6.5 - 8.0 m / ms, contacts do not open at the same time, and there is a problem opening the next contacts, which significantly limits the length of the tube and consequently the number of breaks.

After each operation under short circuit breaker is automatically destroyed and replaced by the following. Thus, the circuit breaker cannot be restored, and for the automatic restart the following breakers are used.

Patent US 6,252,190 (Assignee ABB Research Ltd.) describes a fast reusable explosive power switch, which switches off within half-period when passing zero current. Described switch has one movable slide contact connecting in closed position two fixed electrodes and containing holes for gas outlet after the explosion. With the explosion the movable contact moves, breaking contact with the first fixed electrode. The switch includes several explosive charges built into the first fixed electrode to circuit breaker operating several times. Described switch has a number of disadvantages: the contact is located in an explosion chamber, opening of contact and an arc uprising occurs at high temperature, which increases even greater arc when arc burns. In addition, the pressure in the explosion chamber and heat can cause unintended explosions of other charges, as all the channels on the charges converge in one explosive chamber. Equipment described herein contains; lone contact, and does not limit the voltage in short circuit.

Patent Application US 2011/0080564 describes a solid-state device for ;voltage decreasing in short-circuit for medium and high voltage network. The device comprises a plurality of series-connected cells, consisting of parallel; nonlinear resistors (mostly varistors), power switch contacts and semiconductor switching elements - gate turn-off units (GTO, IGBT).

Under short circuit in this device semiconductor switching elements that shunt power contact, are switched. Semiconductors are chosen such that the voltage drop across them is less of arc voltage. When the semiconductor is closing, energy stored in short-circuit is dissipated in the varistors. Described device does not include a mechanical drive of contacts breaking and is not explosive. The proposed scheme is a fast multi-contact system. However, the [electrical circuit contains a lot of high-speed semiconductor devices and very expensive.; line aim of the invention is to create a high-speed reusable not expensive devices to limit short-circuit current in AC SUMMARY OF TIIE INVENTION This aim is achieved by means of a device to limit short-circuit current in! the short-AC circuits, which contains an explosive charge with a detonation device , at explosion of which gas pushes a piston, located in the explosion; chamber and mechanically connected to the moving part of main contact, designed for continuous operation in normal mode.

The present invention proposes the structure, wherein the considered device contains a unit of [automatic reboot of the explosive charge, which js supplied to the input of the explosion chamber, allowing multiple operations of the unit. Each explosion occurs from the pulse generated by the control unit at short-circuit.

[The main contact is located in a separate chamber of the main contact, isolated from the gas, generated by the explosion. Shunt contacts are connected parallel to the main contact and also located in a separate chamber of shunt contacts unit. When the main contact is disconnected!, electrical current moves to bypass way formed by closed circuit of shunt contacts. iShunt contacts unit comprises a plurality of series-connected contacts.! Since the total contact resistance on series-connected shunt contacts exceeds in many times the contact resistance of the main contact in the normal mode, the current through the main contact is many times greater than the current through the shunt contacts The moving portions of shunt contacts are mounted on a mobile column, which is pushed by the piston of shunt contacts. The piston of shunt contacts is located in the chamber of the piston shunt contacts with holes for gas inlet and outlet.

The present invention proposes the design, wherein the explosion chamber has hole to move gas from the explosion chamber to the chamber of piston of shunt contacts, and this hole is located at the end of the piston: stroke of the main contact. A tube connects the hole in the explosion chamber and the hole in the chamber of piston of shunt contacts. In this case, the time delay between the opening of the main contact and shunt contacts is provided the piston stroke of the main contact. This delay is determined by the time required for the opening of the main contact in conditions of electric current transition to the bypass way formed by shunt contacts.¾ The present invention proposes the structure, wherein fixing of the main [and shunt contacts in the open position is made by pneumatic units - slide-! valve chamber of the main contact and slide-valve chamber of sfiunt contacts,! [each of which includes a slide-valve-rod connected with the unit of return stroke. To ensure fixing the slide-valve chamber of the main contact is! connected to the explosion chamber via a tube. The fixing device is activated under the influence of gas from the explosion chamber, when the piston is at jthe end position and opens up the hole, connected with the specified tube.· The slide-valve chamber of shunt contacts works similarly. This is achieved by a hole in the piston chamber of shunt contacts, located at the [end of the piston stroke, and the hole in the slide:valve chamber of shunt [contacts. Holes are connected by tube. Fixing unit of shunt contacts is actuated at the end of the piston stroke after the opening of shunt contacts.^ The present invention proposes the structure, wherein the gas after the [explosion comes out of the device through an exhaust hole in slide-valve [chamber of the shunt contacts.

To return the main contact from the open to the closed position and to! [create pressure on the closed main contact, a retum pressing unit is located [in the explosion chamber. To return the shunt contacts from an open to a [closed position and to create pressure on the closed shunt contacts, a return pressing unit is arranged in the chamber of piston of shunt contacts. [X The present invention describes the design, wherein the unit of [automatic reboot of explosive charge is designed as electro-mechanical [device comprising a line with cells for the charges that supplies an explosive: [charge into the explosion chamber. Line is connected to a stepper drive: [mechanism.; the main contacts are connected in series with each other and shunt contacts are also connected in series with each other .

When a signal of a short circuit is received, signal to the explosion comes to the first in turn charge, the charge is detonated and pushes the piston mechanically connected with the movable portion of the main contact. The main contact is opened. The current flowing through the main contact passes to shunt circuit contacts. For decreasing of inductance of bus-bars, forming circuit of the main contacts and the shunt contacts, connected parallel, bus bars must be made as multilayer laminated.

The number of consecutive shunt contacts selected such that the voltage drop at the shunt contacts in closed position is lower than voltage drop across the arc at the opening of the main contact. If the total voltage drop across the closed shunt contacts exceeds the voltage drop across the arc at the opening of the main contact, and the arc can occur, the invention shows option, which uses two or more main contacts in series.

In the circuit of the considered device it is also mounted vacuum switch, which prevents re-ignition of the arcs in the opposite direction when current pass through zero.

The present invention proposes also the design, in which the device contains separate subsystem of main contact opening and subsystem of shunt contacts opening, which are controlled by pulses for charges detonation. Order of interaction of main and shunt contacts is given by a common control unit. Pulses are fed through two channels - channel for subsystem of main contact opening and channel for subsystem of shunt contacts opening.

The subsystem of the main contact opening comprises unit of automatic reboot of an explosive charge, the explosion chamber of the main contact, which contains the piston, connected mechanically with the moving part of the main contact, and this explosion chamber also contains the return-pressing unit of the main contact and the holes for the gas outlet from the chamber. The subsystem of main contact opening includes also the chamber of the main contact, comprising the main contact and fixing unit of the main contact. The subsystem of shunt contacts opening comprises unit of automatic reboot of an explosive charge, the explosion chamber of shunt contacts, containing the piston mechanically connected with a movable column of shunt contacts unit, and this explosion chamber also contains the return-pressing unit of the shunt contacts and the holes for the gas outlet from the chamber. The subsystem contains also the chamber of the shunt contacts, including the moving column bearing quantity of moving portions of shunt contacts and also a fixing unit of the column.

Interval between pulses for the explosion coming from the control unit to the first and second units of automatic reboot an explosive charge is selected according to the required time delay between the opening of the main and shunt contacts, determined by the transition time of circuit current from the main to shunt contacts. [X The present invention proposes also design, in which the device contains some additional subsystems of shunt contacts opening, which are controlled by pulses of charges detonation. Pulses for the explosion come from the control unit to all subsystems of shunt contacts opening.

The present invention proposes also the structure, which contains the following design: after explosion, produced by unit of automatic reboot of the explosive charge, the piston of the main contact mecanically pushes the rod, mechanically connected with movable portions of shunt contacts. The piston and the rod are located on common longitudinal axis. Distance between the piston and the rod is determined by required time delay between opening of the main and the shunt contacts. In this structure the piston is placed into an explosion chamber, which contains also return-pressing unit and holes for the gas outlet. The main contact is located in the chamber of the main contact, comprising also fixing unit. The rod with quantity of the shunt contacts are located in the chamber of shunt contacts.

The present invention provides technical solutions, which are innovative and capable of meeting the requirements for their application.

BRIEF DESCRIPTION OF THE DRAWINGS Other advantages of the present invention will be readily appreciated, as the same becomes better understood by reference to the following detailed description when considered in connection with the accompanying drawings wherein: Fig. 1a is schematic view of one embodiment of an explosive device with electro-mechanical unit of automatic reboot of explosion charge with closed contacts.

Fig. 1b is schematic view of one embodiment of an explosive device with electro-mechanical unit of automatic reboot of explosion charge with opened contacts.

Fig. 2a is schematic view of one embodiment of an explosive device with pneumatic unit of automatic reboot of explosion charge.

Fig. 2b is schematic view of one embodiment of an explosive device with pneumatic unit of automatic reboot of explosion charge (3D Image).

Fig. 3 is schematic view of one embodiment of a device in 3D image Fig 4a is schematic view of one embodiment of a column for fastening of movable portions of shunt contacts, made in a shape of a tetrahedron, in which the movable portions of shunt contacts are fixed on tetrahedron sides.

Fig. 4b is schematic view of one embodiment of a column for fastening of movable portions of shunt contacts, made in a shape of a polyhedron, in which the movable portions of shunt contacts are fixed on polyhedron sides. Fig. 4c is schematic view of one embodiment of a column for fastening of movable portions of shunt contacts, in which the movable portions of shunt contacts are fixed on a board.

Fig. 5 is schematic view of one embodiment of a system, in which some devices, operating from one explosion pulse, are used Fig. 6a is a circuit diagram of a device for one phase Fig. 6b is a circuit diagram of a device for one phase with some main contacts Fig. 7 is schematic view of one embodiment of a system containing separately a subsystem of a main contact opening and a subsystem of shunt contacts opening, operating from explosion pulses Fig. 8 is schematic view of one embodiment of a system, containing one subsystem of a main contact opening and some subsystems of shunt contacts opening, operating from explosion pulses.

Fig. 9 is schematic view of one embodiment of a device, in which a piston of the main contact mecanically pushes a rod with shunt contacts DETAIL DESCRIPTION OF THE INVENTION The invention shows different variants of explosive high speed selfrestoring AC fault current limiters. The system 100 is presented (Fig. 1a, 1b) in the form of housing 1. The detonation unit 2, providing operation of explosion charge 3, line 4, feeding explosion charges 3 to explosion place, are mounted on the housing 1. The explosion charges 3 are placed in cells with defined step. Moving of the line 4 may be provided by different ways, for example, by electro-mechanical unit (gear-rack, ratchet, screw - nut, etc.), by pneumatic unit, etc. As an example, it is proposed electro-mechanical unit of automatic reboot of explosion charge with the following structure: the rack 5, fastened to the line 4, interacts with the gear 6, mounted on the shaft of the stepper motor 7, which is attached to the housing 1 through the holder 8.

The explosion chamber 9 contains a piston 10, firmly pressed to the bottom of the chamber by the spring 11. Spring adjustment is provided by the nut 12. The device contains also the tube 13, designed to remove explosive gas from the chamber 9 to the chamber 14. The main contact 15 is located in the chamber 16. Movable portion of the main contact 17 is mounted on the tail-end of the piston (10) through dielectric 18. The piston 10 is connected with a rod 19, at the end of which it is made a groove 20, located at slidevalve chamber 21, containing slide-valve-rod 22, connected with a return stroke unit 23. The slide-valve chamber 21 is connected by the tube 13 with explosion chamber 9. All above mentioned elements are located in the chamber 16.

The piston of shunt contacts 24 is located in the chamber 14. The piston 24 is under influence of the spring 25, adjusted by the nut 26. The hole with the tube 27 is destined for gas outlet. Tail-end of the piston 24 is connected with the column 28, bearing the movable portions of shunt contacts 29. Fixed portions 30 are fastened in the chamber of shunt contacts 31. The rod 32 is fastened to bottom portion of the column 28. The rod 32 has the groove 33, located at the slide-valve chamber 34 containing slide-valve-rod 35, connected with a return stroke unit 36. The slide-valve chamber 34 is connected by the tube 27 with the chamber 14.

The hole 38, located in the chamber 34, is destined for outlet of gas from the entire device 100.

The presented device 100 is controlled by the explosion control unit 40.

In the initial position (Fig. 1a) the rack 5 with the line 4 are mounted so that the axis of a cell of explosion charge 3 coincides with inlet of the explosion chamber 9. At that the main contact 15, 17 and shunt contacts 29, 30 are closed. When short-circuit is occurs, the explosion control unit 40 feeds a pulse to the detonation unit 2, providing explosion of the charge 3. Explosive gas, entering in the chamber 9 (Fig.1b), press the piston 10. The piston moves, pressing the spring 11. The movable portion of the main contact 17 passes a distance given by the stroke of the piston 10 up to opening of a chamber hole, connected with the tube 13. The rod 19 of the piston 10 moves and provides coincidence of its groove 20 with location of slide-valve-rod 22, which enters to the groove 20 under pressing of gas through the tube 13 between the explosion chamber 9 and the slide-valve chamber 21, fixing the rod 19 with movable portion of the main contact 17 in open position. At the same time, at the moment of displacement of the piston 10 up to end of its stroke, explosive gas through the tube 13 push the piston 24 of shunt contacts in the chamber 14. The piston presses the spring 25. The column 28, connected with the piston 24, moves and provides opening of shunt contacts 29 - 30. At the end of stroke of the piston 24 the hole of the tube 27 is opened, and gas come to slide-valve chamber 34. Displacement of the column 28 together with the rod 32 leads to coincidence of the groove 33 with slide-valve-rod 35, which under gas pressure enters in the groove 33. It provides a holding of the column in position when shunt contacts are opened.

At restart of the network, when time of switching-on may be much more, the control unit 40 sends pulses to return-stroke units 36, which pulls the slide-valve-rod 35, releasing the column 28. The column 28 under pressing of the spring 25 returns in initial position, providing closing of contacts 29-30. The control unit 40 sends also pulses to return-stroke units 23, which pulls the slide-valve-rod 22, releasing the rod 19, that provides closing of the main contact 15-17. The device is ready for new operation. The control unit 40 also sends pulse to the electro-mechanical unit of automatic reboot of explosion charge. The pulse is sent to the stepper motor 7, which through the gear 6 and the rack 5 (Fig. 1a) moves the line 4 with the following charge 3 to the inlet of the explosion chamber 9, performing reboot of explosive charge.

Fig. 2a, 2b shows an example of operating of a device 101 with pneumatic unit of explosive charge reboot, which provides moving of the line 4. The unit consists of camera 41, in which the piston 42 is placed. The piston 42 is pressed by the spring 43. The force of the spring is adjusted by the nut 44. The camera is connected with explosion chamber 9 by the tube 45. The piston stroke 42 is limited and equal to step between cells of explosive charges 3. On the end of the piston 42 the holder 46 is fastened. On the holder it is mounted the ratchet 47 being in cohesion with the ratchet line 48, which is connected with the line 4, feeding explosive charges 3.

For reboot the explosive charge after explosion and after moving of the piston 10 of the main contact, explosive gas comes from the explosive chamber 9 through the tube 45 to the camera 41. At that the piston 42 begins to move. The piston 42 pushes the holder 46 with ratchet 47. The ratchet 47 forwards the ratchet line 48, connected with the line of explosive charges 4, the line 4 moves on one step and is ready to the following explosion.

Fig.3 shows 3D image of described device. Fig. 4 disclosures different examples of shunt contacts unit design: in a form of tetrahedron (Fig. 4a), in which the movable portions of shunt contacts are fixed on tetrahedron sides, in a form of a polyhedron (Fig. 4b), in which the movable portions of shunt contacts are fixed on polyhedron sides, in a form of a board (Fig. 4c). It is possible other options of the shunt contacts unit.

Fig.5 describes the system, which contains several explosive devices operating from a single control signal. In this case the main contacts of each device are connected in series one to another and shunt contacts are also connected in series one to another. At that all shunt contacts are connected parallel with circuit of series main contacts. This system may be used for networks with higher voltages.

Fig. 6a illustrates electrical scheme 50 of the device for one phase of network. The device contains the main contact 51 and group of shunt contacts 52 connected in series. As shows Fig. 6b, unit of main contacts 53 may contain some series main contacts. The scheme comprises also a vacuum switch 54, which opens, when the current pass through zero, thus preventing re-ignition of the arc with increasing reverse polarity. Varistors (55) are used for surge protection in case of emergency, if the arc on the shunt contacts will not light.

Fig.7 shows the system, in which operating of the main and shunt contacts are controlled by signals of the control unit 40. In this case the system contains separate subsystem of main contact opening 60 and subsystem of shunt contacts opening 61, which are controlled by pulses for charges detonation, coming through separated channels.

Correspondently, each subsystem contains its unit of automatic reboot 3 of an explosive charge. The subsystem of a main contact opening 60 comprises the explosion chamber of the main contact 9, which contains the piston 10, connected mechanically with the moving part 17 of the main contact, and this explosion chamber also contains the return-pressing unit of the main contact and the holes for the gas outlet from the chamber. The subsystem of main contact opening includes also the chamber of the main contact 16, comprising the main contact 15-17 and fixing unit of the main

Claims (16)

16 CLAIMS

1. Explosive high-speed self-restoring reusable device to limit short-circuit current in AC networks, which contains: - A main contact, the movable portion of which is connected mechanically to a drive rod, - An additional shunt contact in parallel with the main contact, - A return-pressing units for pressing of contacts in closed position, - fixing unit, designed to fix the contacts in the open position, - A drive to open contacts, and said drive includes an explosive charge with detonating unit and a control unit for generating a pulse of igniting an explosive charge, wherein, in order to ensure the high-speed performances and self-restore upon numerous operations, said device further comprises: - Unit of automatic reboot of the explosive charge; - Explosion chamber containing a piston of the main contact, and this piston is mechanically connected with movable portion of said contact, and the explosion chamber has also return-pressing unit and holes for the gas outlet from the explosion chamber, and the holes are located at the end of the piston stroke; - The chamber of the main contact, comprising the main contact and fixing unit of the main contact; - Chamber of a piston of shunt contacts, in which the piston of shunt contacts is connected mechanically with moving column of shunt contacts, connected mechanically with movable portions of said shunt contacts, and this chamber has also return-pressing unit and holes for gas inlet and outlet; 17 - Chamber of shunt contacts, in which said moving column with quantity of the shunt contacts are located. - Tubes connecting the outlet holes in the explosion chamber with inlet holes in the chamber of the piston of shunt contacts unit, and delay time between the opening of the main contact and shunt contacts is provided by the piston stroke of the main contact.

2. Explosive device to limit short-circuit current in networks of alternating current according to claim 1 , which includes as the fixing unit of the main contact slide-valve chamber containing the slide-valve-rod, connected with a return stroke unit, and also the inlet hole in said chamber is connected by an additional tube with additional outlet hole of the explosion chamber located at the end of the piston stroke.

3. Explosive device to limit short-circuit current in AC networks according to claim 1 , which includes as the fixing unit of the shunts contacts slide-valve chamber containing the slide-valve-rod, connected with a return stroke unit, and also the inlet hole in said chamber is connected by an additional tube with the additional outlet hole of the chamber of the piston of shunt contacts located at the end of the piston stroke.

4. Explosive device to limit short-circuit current in AC networks according to claim 1, in which the gas outlet of the device is located in the slide-valve chamber of fixing unit of shunt contacts. 18

5. Explosive device to limit short-circuit current in AC networks according to claim 1 , In which unit of automatic reboot of an explosive charge is designed as electro-mechanical unit comprising a line with cells for the charges supplying an explosive charge to the input of the explosion chamber, and this line is connected to a stepper drive mechanism

6. Explosive device to limit short-circuit current in AC networks according to claim 1 , in which unit of automatic reboot of an explosive charge is designed as pneumatic unit comprising a chamber and a piston of pneumatic unit, and this piston is mechanically connected with the line with cells for supplying an explosive charge to the input of the explosion chamber, and this pneumatic unit is connected by additional tube with additional outlet hole in the explosion chamber, and said hole is located at the end of the piston stroke

7. Explosive device to limit short-circuit current in AC networks according to claim 1 , in which the column for mounting of movable portions of shunt contacts is designed as a rectangular profile

8. Explosive device to limit short-circuit current in AC networks according to claim 1 , in which the column for mounting of movable portions of shunt contacts is designed as a polyhedron profile 19

9. Explosive device to limit short-circuit current in AC networks according to claim 1 , in which the column for mounting of movable portions of shunt contacts is designed as a flat panel.

10. Explosive device to limit short-circuit current in AC networks according to claim 1 , in which the column for mounting of movable portions of shunt contacts is made inside the hollow to allow heat removal from the contacts.

11. Explosive device to limit short-circuit current in AC networks according to claim 1 , in which, on purpose to limit the short circuit current by reducing the total voltage in the short-circuit, a lot of shunt contacts are connected in series.

12. Explosive device to limit short-circuit current in AC networks according to claim 1 , in which, on purpose to increase the reliability of the current transition from the main contact to a quantity of shunt contacts, connected between themselves in series, during opening of the main contact, one or more of series contacts are additionally connected in series with the main contact, and the movable portions of the contacts are mechanically connected with the piston of explosion chamber.

13. Explosive high-speed self-restoring reusable device to limit short-circuit current in AC networks according to claim 1 , 20 which, on purpose to increase the range of permissible voltage of network, contains additional said explosive high-speed self-restoring reusable devices, and the main contacts of all devices are connected in series within each device and between devices, and also shunt contacts of all the devices are connected in series with each other as in each device and between devices, and control signals to an explosion of each device connected in parallel and connected to a single control unit explosion.

14. Explosive high-speed self-restoring reusable system to limit short-circuit current in AC networks, wherein, in order to ensure the high-speed performances and self-restore upon numerous operations, said device further comprises: -separate subsystem of main contact opening and separate subsystem of shunt contacts opening, which are controlled by pulses of control unit through separate channels - channel for subsystem of main contact opening and channel for subsystem of shunt contacts opening, - and subsystem of main contact opening contains unit of automatic reboot of an explosive charge, the explosion chamber of the main contact, which contains the piston, connected mechanically with the moving part of the main contact, and this explosion chamber also contains the return-pressing unit of the main contact and the holes for the gas outlet from the chamber and the chamber of the main contact, comprising the main contact and fixing unit of the main contact; - and subsystem of shunt contacts opening comprises unit of automatic reboot of an explosive charge, the explosion chamber of shunt contacts, containing the piston, mechanically connected with a movable column of shunt contacts unit, and this explosion chamber also contains the return 21 pressing unit of the shunt contacts and the holes for the gas outlet from the chamber, and also the chamber of the shunt contacts, including the moving column bearing quantity of moving portions of shunt contacts and fixing unit of the column, and the interval between pulses for the explosion coming from the control unit to the subsystem of main contact opening and to the subsystem of shunt contacts opening! is selected from the required time delay between the opening of the main and shunt contacts, determined by the transition time of circuit current from the main to shunt contacts.

15. Explosive high-speed self-restoring reusable system to interrupt shortcircuit current in networks of alternating current according to claim 14, which on purpose to increase the range of permissible voltage of network contains additional subsystems of shunt contacts opening

16. Explosive high-speed self-restoring reusable device to limit short-circuit current in AC networks, which contains: - A main contact, the movable portion of which is connected mechanically to a drive rod, - An additional shunt contact connected parallel with the main contact, - A return-pressing units for pressing of contacts in closed position, - fixing unit, designed to fix the contacts in the open position, - A drive to open contacts, and said drive includes an explosive charge with detonating unit and a control unit for generating a pulse of igniting an explosive charge,