WO2003060939A1

WO2003060939A1 - Circuit breaker

Info

Publication number: WO2003060939A1
Application number: PCT/CN2002/000773
Authority: WO
Inventors: Weiqi Liu
Original assignee: Weiqi Liu
Priority date: 2001-11-05
Filing date: 2002-10-31
Publication date: 2003-07-24
Also published as: CN1234140C; CN1417818A; AU2002344034A1

Abstract

The circuit breaker of this invention is designed with the theory of no electric arc and a serious of theories about circuit breaking. It breaks the old designing theory and reaches a new level. The circuit breaker has setting-off unit, contactor unit, switch structure and control unit. The setting-off unit can cut off the circuit with no electric arc or with passing off the electric arc. Contactor unit can transfer the circuit with no electric arc or with little electric arc. Switch structure is small and simple. Control unit can make easy controlling program. It can satisfy the needs of modern electric network and it will replace the breakers and contactor switches used for all kinds of modern voltage levels.

Description

0773 current cut off

Technical field

The invention relates to circuit breakers of various types of capacity series of all voltage levels of the power system and the replacement of larger-capacity contactors, and is a major technical revolution in the field of power switches. Background technique

The existing arc extinguishing devices of various types of circuit breakers and contactors are developed based on various arc extinguishing principles in the arc extinguishing theory, and are designed according to the breaking of the short-circuit current. They are required to be in operation. It is possible to consider the most severe electrical conditions when short-circuit current is encountered to consider mechanical operating characteristics. In this way, a strong mechanical impact during each heavy-load operation will significantly affect the service life of the circuit breaker. When a traditional circuit breaker and a synchronous circuit breaker are opened and cut off, a high-speed race of physical changes takes place between their dynamic and static contacts. A competition between the voltage recovery speed and the growth rate of the medium strength between the dynamic and static contacts. The contact separation speed And thermal breakdown, electrical breakdown speed and arc burning speed competition. Participating in such competitions with existing mechanical switches requires not only high-tech sophisticated technology, but also manufacturing difficulties. In the fields of medium-voltage, high-voltage, ultra-high-voltage, and ultra-high-voltage, many countries, especially developed countries, have invested a lot of research funds in the research and development of circuit breakers. After years of continuous efforts to solve key problems, they still cannot meet the needs of modern development of power systems. There are many deficiencies in the existing circuit breakers in terms of technical performance, breaking capacity, switching life, especially electrical life, manufacturing cost, switch volume and safety and reliability. For example, the problem of opening speed, contact bounce, closing pressure, strong mechanical impact, electric arc, especially the short-circuit current, electrical wear of the switch contacts, and intelligent control accuracy. In recent years, some developed countries and multinational companies have developed many new products for circuit breakers, such as SF ₆ circuit breakers in the field of high voltage and permanent magnet synchronous circuit breakers in the field of medium voltage. . Disclosure of invention

1 Overview

1. Guideline

The invention relates to circuit breakers of various types of capacity series of all voltage levels of the power system and the replacement of larger capacity contactors, and is a major technical revolution in the field of power switches.

The existing switching-off and arc-extinguishing devices of various types of circuit breakers and contactors are developed based on various arc-extinguishing principles in arc-extinguishing theory, and are designed according to the breaking of short-circuit current. They are required to be in operation. It is possible to consider the most severe electrical conditions when short-circuit current is encountered to consider mechanical operating characteristics. In this way, a strong mechanical impact during each heavy-load operation will significantly affect the service life of the circuit breaker. When a traditional circuit breaker and a synchronous circuit breaker are opened and cut off, a high-speed race of physical changes takes place between their dynamic and static contacts. A competition between the voltage recovery speed and the growth rate of the medium strength between the dynamic and static contacts. The contact separation speed And thermal breakdown, electrical breakdown speed And the arc burning speed race. Participating in such competitions with existing mechanical switches requires not only high-tech sophisticated technology, but also manufacturing difficulties. In the fields of medium-voltage, high-voltage, ultra-high-voltage, and ultra-high-voltage, many countries, especially developed countries, have invested a lot of research funds in the research and development of circuit breakers. After years of continuous hard work, they still cannot meet the needs of modernized development of power systems. There are many deficiencies in the existing circuit breakers in terms of technical performance, breaking capacity, switching life, especially electrical life, manufacturing cost, switch volume and safety and reliability. For example, the problem of opening speed, contact bounce, closing pressure, strong mechanical impact, electric arc, especially the short-circuit current, electrical wear of the switch contacts, and intelligent control accuracy. In recent years, some developed countries and multinational companies have developed many high-tech products for circuit breakers, such as SF ₆ circuit breakers in the high voltage field and permanent magnet synchronous circuit breakers in the medium voltage field. .

According to two rare production accidents, the present invention directly operated high-voltage motors of 625 kw and 2500 kw with isolation switches without causing arcs and causing serious accidents. The arc-free interruption theory and its discussion have been discussed since 1968. application. On April 20, 1978, Comrade Yu Weihua, former State Science and Technology Commission, attached great importance to and supported the two early papers. He had arranged discussions at the Institute of Electrical Engineering, Institute of Physics, and Department of Electric Power, Tsinghua University. Professor Qian Jiayi believes that it is theoretically correct, but there will be many difficulties in realizing it, and he will guide future research directions in person. On June 5, 1978, it was reviewed and instructed by Cao Rongjiang, the former director of the high-voltage electrical room of Wuhan High Voltage Research Institute. Later, with the support of the relevant leaders of Shaanxi Province, the Science and Technology Commission and Xi'an Jiaotong University, and the continuous guidance of Professor Wang Jimei, from 1997 to 1999 in the School of Electrical Engineering, Xi'an Jiaotong University, Shaanxi Switchgear Factory, and the Second Ministry of Ordnance Industry of China With the cooperation of No.3 Research Institute, experiments on the principle of arc-free or micro-arc interruption of single-phase simulator of explosive intelligent circuit breaker were carried out. Based on successful experiments, the arc-free interruption theory and a series of interruption principles that have been innovatively studied for more than 30 years are summarized. The new theory breaks through the design ideas of traditional circuit breakers, reducing heavy-load operations to no-load or light-load operations during each opening and closing operation, and transforming high-speed competition-type dynamic interruption of switch contacts into switch contacts. Arc-free opening or micro-arc opening and closing under static transfer interruption. Under the guidance of the new theory and principle, a current interruption switch has been developed, which can solve the technical problems of many of the disadvantages of the above circuit breakers and meet the needs of modernization of the power grid. The breaking device makes a significant contribution. After searching that there is no technical means for such a disconnect switch at home and abroad, after the international application for the invention patent, it will generate significant economic benefits for China. BRIEF DESCRIPTION OF THE DRAWINGS

Figure 1. Functional block diagram of a miniature interrupting device;

Figure 2. Functional block diagram of a micro switch device;

Figure 3. Structure diagram of tubular mercury interrupter;

Figure 4. Structure diagram of multi-channel insulation barrier tubular mercury interrupter;

Figure 5. Structural diagram of a tubular sodium interrupter with a piston; Figure 6, a structural diagram of a tubular sodium interrupter with a bellows;

Figure 7.Single transfer short-open contact unit structure diagram;

Figure 8.Single transfer long open distance contact unit structure diagram;

Figure 9 Structure diagram of a double-transferred short-open contact unit;

Figure 10. Structure diagram of a double transfer long open distance contact unit;

Figure 11. Structure diagram of operating a single transfer cut-off switch;

Figure 12, Figure 11 three stable state diagrams during operation;

Figure 13: Structure diagram of double-acting single-transfer interruption switch;

Figure 14, Figure 12 three steady state diagrams during operation;

Figure 15.Structural diagram of single-action double-transfer cut-off gate;

Figures 16 and 15 are four steady state diagrams during operation;

Figure 17: Structure diagram of double-acting double-transfer interruption switch;

Figure 18, Figure 17 four steady state diagrams during operation;

Figure 19: Schematic diagram of electromagnetic lock structure;

Figure 20: Schematic diagram of permanent magnet lock structure;

Figure 21: Schematic diagram of the monostable permanent magnet operating mechanism;

Fig. 22 Schematic diagram of the structure of the bistable permanent magnet operating mechanism;

Figure 23: Schematic diagram of the tri-stable permanent magnet operating mechanism;

Figure 24. Schematic diagram of the four-steady-state permanent magnet operating mechanism;

Figure 25.Principle of anti-bouncing automatic locking device mechanism

Figure 26. Schematic diagram of auxiliary switch structure;

Figure 27. Circuit diagram of single operation single transfer control unit;

Figure 28. Circuit diagram of dual-operation single-transfer control unit;

Figure 29. Circuit diagram of single operation and double transfer control unit;

Figure 30. Circuit diagram of dual-operation dual-transfer control unit;

1. 2 design principles

The cut-off switch mainly includes four components such as a cut-out, a contact unit, a switch mechanism and a program control unit. The present invention adopts the interruption principle of the non-arc interruption principle, 8-current-limiting and breaking principle, 16-current principle of repulsive breaking, and 12-state principle of static interruption to develop a current interrupter. The current-limiter and non-current-limiting types of the circuit breaker can reliably and reliably cut off the loop current without arcing or extinguishing, static or fretting, and make full use of the large current in the loop, especially the electric repulsion force of the short-circuit current. Performs fast current-limiting interruption. The present invention adopts the interruption principle 2 of the arc-free interruption theory—the cold-state separation principle, the interruption principle 13—the current transfer principle, the interruption principle 15—comprehensive interruption principle and the contact principle of the disconnector, and develops a knife gate type Contact unit. When the contacts are opened, the current in the circuit is first transferred to the current interrupter, and the current interrupter cooperates with the current interrupter to perform comprehensive interruption. After the current is cut off, the dynamic and static contacts are cold-arc-free, and the power is safely isolated. The invention adopts the non-arc current cut-off principle 3-fast response principle, current cut-off principle 17-light load breaking principle and operation principle of the isolating switch to develop a direct-acting switch mechanism. The mechanism is simple and lightweight, and has a fast response to the opening and closing. It can perform open or close operation with or without light load. The development of the program control unit is relatively simple. It uses low-grade program control and is programmed into a fool-type step-by-step operation.

1. 3 design principles

1. 3. 1 design principles of interrupters

During the opening and closing process of the cut-off switch, the current interrupter is responsible for the instantaneous current-carrying task of opening and closing the circuit, and its working time is very short, usually within 10ms or about 30ms. Therefore, it is not necessary to consider long-term heating temperature rise and thermal stability when designing, but also need to consider instantaneous high temperature resistance, dynamic stability and pressure resistance performance, and related interruption parameters. Then the load-carrying surface of the current interrupter and each current-carrying element in the circuit connected to it can be designed very small. Most circuit breakers are static, there is no mechanical transmission connection, the sealing problem is easy to solve, and the manufacturing difficulty is not great. The volume of the circuit breaker can be designed very small. In fact, it is a miniature switching device (which can be switched on The circuit can also break the circuit) or miniature interruption device (only the circuit can be interrupted), limited current type and non-current limited type, with or without arc interruption and also arc extinguishing interruption. Some circuit breakers have a long life and can be theoretically designed to be permanent; some are disposable and can be designed to automatically pop up and replace spare parts immediately after each interruption; some have a longer life and can be designed to be able to Periodically (eg several years) it is convenient to change the connection form of the spare parts (like plug-in fuses).

1. 3. 2 design principles of contact units

The design of the contact unit must not only ensure reliable power supply during the operation of the disconnect switch, but also be able to quickly transfer the current interruption under high-speed dynamic conditions to the static or easy interruption of the interrupter. It is necessary to eliminate the contact bounce when closing, and solve the problem of butt-type closing pressure; eliminate the electrical wear of the contacts, and solve the problems of electrical life and manufacturing difficulty. When using a miniature interrupter-type interrupter, the design of the contact unit must have the function of turning on the current and isolating the power source. When the current is turned on, the closing speed of the contact has reached the maximum value. If there is no time for breakdown or a significant large arc has not yet formed, it can be closed quickly. When the load is opened without interrupting any load current, the opening and closing operations are arc-free or micro-arc operation. When a micro-switch-type current interrupter is used, the design of the contact unit only needs to have the function of connecting voltage and isolating the power source, and it has no load or disconnection, which is obviously arc-free operation. Then the contact unit does not have the difficulty of manufacturing, and has a long service life and low production cost.

1. 3. 3 design principles of switching mechanism

The design of the gate mechanism should eliminate or simplify the transmission mechanism and contact travel mechanism, minimize the transmission chain, and directly apply the operating power source to the contact. In the opening operation, the response of the initial opening is extremely fast, and it can be quickly separated. The locking device in the switch requires instantaneous automatic locking and fast electric unlocking. It is not necessary to consider the closing pressure of the contact butt in the design. To reduce the closing and opening forces and their power consumption, it can be reduced to 1/3 ~ 1/10 of the existing circuit breaker, reaching no load or light. Contain the desired performance. Can eliminate strong mechanical impact, solution Solve the problem of mechanical life, reduce weight and volume, reduce production costs and solve manufacturing difficulties.

1. 3. 4 design principles of the control unit

The design of the control unit shall be based on the function setting of the interrupter. One procedure shall be applicable to the miniature interrupter type interrupter, and the other procedure shall be applicable to the miniature switch device interrupter. It should be able to resolve complex, fast, accurate, reliable, and high-precision intelligent control operations into simple, slow, and fool-proof controls. The low-level step-by-step program control unit is compiled, with simple structure and few components, and naturally low cost and cost. It not only solves the problem of control accuracy, but also solves the problem of opening speed. It is applied to the control design of AC short-circuit current. When a current-limiting interrupter is used, its control set time-the time to detect the ringing and transfer current should be as short as possible, and within 3ms, its control unit must adopt Fast response PC control. When a non-current-limiting interrupter is used, the short-circuit current control design far from the power plant requires a delay of about 45ms from the instant of the short-circuit before transferring the current to the interrupter in time; for the short-circuit current near the power plant Control design requires a delay of about 150ms. The specific delay time can be calculated according to the parameters of the specific circuit. The decay time of the maximum transient component of the short-circuit current can be determined to determine the time when the first zero-crossing current occurs after the short-circuit. The interrupter can be controlled to assume the task of transferring current and breaking the circuit when the transient component of the short-circuit current decays to zero crossing, which can ensure the shortest working time of the interrupter, its current-carrying cross-section and volume are the smallest, and can be controlled by electrical appliances or PC control.

1. 4 overall structure

The overall structure of the interrupt switch is composed of a control unit, a switch mechanism, a contact unit and an interrupter. According to the type of the current interrupter, it can be divided into two types of structures. One type is the current interrupter equipped with a micro interrupter, which can be called a single transfer interrupt switch structure. The functional block diagram is shown in Figure 1. The other type is a current interrupter equipped with a micro switch device, which can be called a double-transfer interruption switch structure. The functional block diagram is shown in Figure 2.

2 Design scheme of current interrupter

2. 1 Introduction —

2. 1. 1 function of the interrupter

The interrupter is a current-limiting or non-current-limiting micro interrupter or micro switch device without arc interruption or arc interruption interruption. The micro interrupter can only be used to disconnect the circuit and cannot be used to switch on. Circuit; a miniature switching device is essentially a very small "circuit breaker". The various design schemes described in this article can be developed into circuit breakers with various breaking capacities of different voltage levels, which can meet the needs of AC or DC low voltage, medium voltage, high voltage, ultra high voltage and ultra high voltage power systems. Make the disconnect switch easily realize arc-free operation or micro-arc operation. The interrupter can be easily replaced in the interrupt switch, which can improve the service life of the switch dozens of times, improve safety and reliability, and greatly reduce the use cost.

2. 1. 2 Types of interrupters

The interrupter is classified into limited flow type and non-restricted flow type according to the cut-off characteristic, with or without arc cut-off type and arc-extinguished cut-off type; classified according to the operating characteristics of static type and micro-movement type; classified according to the cut-off medium, solid-state , Liquid type, gaseous type and vacuum type. The invention designs nine types of circuit breakers: a. Mercury circuit breaker, b. Sodium circuit breaker, c. Fuse circuit breaker, d, PTC (Positive Temprature Coeffcient) circuit breaker, e, thyristor circuit breaker, f, micro-motion circuit breaker, g, rocker circuit breaker, h, electronically controlled circuit breaker, i , Magnetically controlled interrupter. Wherein &, b, c, and d are miniature interruption devices, and e, f, g, h, and i are miniature switching devices. The voltage level and breaking capacity of thyristor interrupters are limited by their own performance, and their prices are particularly expensive; and the switching performance of ^ g, h, i four types of interrupters has significant advantages over their respective, can be It meets the requirements of various voltage levels and breaking capacity, which will be described later in another article. Here are five types of interrupters: &, b, c, d, and e.

2.2 Mercury circuit breaker

2. 2. 1 structural principle

Mercury current interrupter is a kind of current-limiting type arc extinguishing static static interruption device. Its structure is basically the same as that of fuse. See Figure 3, Figure 3 (a) is a circular tube structure, Figure 3 (b) is a flat tube structure. In the figure, s ₁ is a pressure-resistant and high-temperature arc-resistant insulating shell, s ^ ns ₃ is a copper cap with a copper connection plug, and S ₄ is mercury placed in a small groove in the bottom of the shell. Closed by a copper cap. The shell is filled with air or vacuum, high-pressure gas, insulating oil, SF ^ n C ₃ F _6, etc., and a suitable gas or liquid insulation medium with good arc extinguishing performance can be selected according to the voltage level. The current cut-off principle is relatively simple. When the current is passed through the mercury conductor with a small cross-section in the small slot, it quickly heats up to become mercury vapor. When the current crosses zero, the arc extinguishes the interruption circuit. After a short period of heat dissipation, the mercury vapor cools back to liquid mercury and flows back naturally into a small groove in the bottom of the tube to prepare for the next interruption. In order to increase the interruption effect, the length of the insulation tube shell can be increased and multiple insulation barriers can be added. Only the small grooves at the bottom of the tube shell are connected to each other, as shown in Figure 4. When this structure is working, a high-speed gas blowing nozzle for arc extinguishing can be formed at a small groove at the bottom of each barrier, and the arc is divided into multiple small sections, which is conducive to cooling and quenching, increasing the arc pressure drop and its resistance, and can prevent The arc reignited. If the requirements of the ultra-high voltage level cannot be met, such multiple multiple insulation barriers may be connected in series to increase the number of arc breaks and the length of the arc. Multiple serially isolated small mercury tanks can be set in the same shell, and several such tubes can be connected in series, but all small tanks must be in the same horizontal plane to ensure that mercury is in the small tank. Uniform distribution within.

2. 2. 2 working principle

The cut-off switch equipped with a mercury interrupter needs to be arc-extinguished during the manufacturing of the contact front end of the dynamic and static contacts to make an arc-extinguishing contact end. When used in low-voltage and medium-voltage power supply systems, the air medium can meet the conditions of use. When used in medium-voltage and above power supply systems, the contact system needs to be placed in insulating oil or other insulating media. During the closing of the cut-off switch, the dynamic and static contacts are first connected to the circuit, and then the circuit breaker is connected in parallel in the circuit to prepare for the opening. The moving contact is quickly closed in one place. When the moving contact is separated to the preliminary opening position during the opening process, the current in the circuit is automatically transferred to the current interrupter. After the current is quickly limited by the interrupter, the moving contact will continue to separate to the opening position. Rear position, safely isolate power. It can also be considered that during the opening process of the cut-off switch, when the breaking speed of the cut-off device is a little faster than the opening speed of the moving contact, as long as the time is suitable, it can be quickly opened in place at one time without the need to divide in steps. Programmable gate control System.

2. 2. 3 scope of application and characteristics

Mercury circuit breakers are light in weight, small in size, easy to manufacture, low in price, reusable, have a long life, and have current limiting characteristics. They are suitable for AC or DC power circuits with frequent operation of various voltage levels. The disadvantage is that it must be placed horizontally during work. It needs a certain heat recovery time after the current is cut off. It can only be used to break the middle circuit and cannot be used to connect the circuit.

2.3 Sodium circuit breaker

2. 3. 1 structural principle

Sodium interrupter is a micro-flow micro-interrupter with current-limiting arc extinguishing and interruption. Its structural principle is shown in Figure 5. Figure 5 (a) is a circular tube structure with a piston at one end, which is suitable for Single operation single transfer type cut-off switch; Figure 5 (b) is a circular tube structure with pistons at both ends, which is suitable for double operation single transfer type cut-off switch. The figure shows a pressure-resistant, high-temperature arc-resistant insulating shell with a thin pipe in the middle. N ₂ is the copper cap of the closed shell, ^ and N ₉ are the copper caps of the closed shell with the piston, and N ₄ is The metal cavity filled with the copper cap cavity at both ends of the tube shell is filled with sodium metal, N _s and N ₇ are pistons for squeezing sodium, and N ₆ and N ₈ are insulating ejector rods connected to the piston. The copper caps on both ends of the tube can be plugged into the designated copper sockets in the cut-off switch to connect the circuits on both ends of the socket. The current cut-off principle is relatively simple. When the current is passed through the sodium conductor with a small cross-section in a thin pipe, it quickly generates heat and turns into sodium vapor. It quickly pushes the piston, which causes the resistance in the interrupter to increase sharply. A current-limiting breaking circuit. After a short period of heat dissipation, the sodium vapor cools back to a relatively soft solid state, and can be squeezed to maintain good contact during the closing process, preparing for the opening and closing of the flow.

The insulating tube shell can be made of high alumina ceramics or other materials with superior performance. The connection with the copper caps at both ends can be welded with a valve metal (iron-nickel-cobalt alloy). The length of the shell can be selected according to the different requirements of various voltage levels, and the appropriate insulation withstand voltage distance can be selected. The thickness of the shell can be determined according to the impact strength of the short-circuit arc. There is also a sodium interrupter that uses a corrugated tube instead of a piston. Its structural principle is shown in Figure 6. Figure 6 (a) is a circular tube structure with a corrugated tube at one end, and Figure 6 (b) is a band with both ends. Round tube structure with bellows. In the figure, N „is a ceramic shell with a thin pipe in the middle, N ₁₂ , N ₁₃ and N ₁₉ are copper caps connected to the shell, and N ₁₄ is filled in the cavity of the shell that connects the two ends of the copper cap and the bellows. Metal sodium, N ₁₅ and N ₁₇ are bellows, and N ₁₆ and N ₁₈ are insulating end caps that close the bellows. The copper caps at both ends of the round pipe can be inserted into the designated copper sockets in the cut-off switch, and the sockets can be connected. The circuit at both ends. The principle of its current interruption is the same as that of the structure shown in Figure 5. Its sealing performance and use effect are better. If the self-closing force of the bellows can match the impact pressure of the arc at the time of interruption, it can also be used. Made of static miniature interruption device.

2. 3. 2 working principle

The working principle of a circuit breaker equipped with a sodium circuit breaker is basically the same as that of a mercury circuit breaker. See the description in section 2.2 of this section. The difference is that a dedicated link is connected to the moving contact of the operating mechanism and the operating lever of the semi-static contact in the interrupt switch. When the closing process is performed, the moving contact and the static contact and the semi-static contact are connected. When the head is connected to the circuit, the special connecting rod can respectively push the insulating jacks N ^ Π Ν ₈ in the interrupter, which can squeeze gold The presence of sodium keeps them in good contact and prepares them for shut-off. When the brake is opened, the current can be automatically transferred to the interrupter as soon as the moving contact and the semi-static contact are separated. At the same time, the special connecting rod on the operating lever also leaves the insulating ejector in the interrupter in time. After the circuit breaker quickly limits the current and cuts off the circuit, the moving contact continues to separate to the post-opening position to safely isolate the current.

2. 3. 3 scope of application and characteristics

The sodium interrupter is small in size, easy to manufacture, reusable, and has a long service life. It has excellent current limiting characteristics and can be used in AC or DC power circuits with frequent operation of various voltage levels. The disadvantage is that it needs a certain heat recovery time after the current is cut off. It can only be used to break the circuit and cannot be used to connect the circuit.

2. 4 fuse circuit breaker

2. 4. 1 structural principle

Fuse interrupter is a kind of disposable static miniature interruption device with arc extinguishing and interruption. Its structure is basically the same as that of fuse. The difference is that the working time of the current interrupter is very short, only milliseconds. The temperature rise and thermal stability issues are not considered in the design. Its volume is small and the metal fuse is thin. In addition to the quartz sand filled in the housing of the interrupter, vacuum, high-pressure gas or liquid, such as insulating oil, hydrocarbon, SF ₆ and C ₃ F ₆ and other arc-extinguishing insulating media, can be considered for development. There are two types of interrupters: flow-type and current-limit type. What needs to be considered is that after each time the circuit breaker cuts off the circuit, it is necessary to automatically replace a spare circuit breaker at the same time as the end of the analysis. The structural principle of the automatic replacement device is also relatively simple. principle.

2. 4. 2 working principle

The cut-off switch equipped with a fuse interrupter works basically the same as a mercury interrupter, see this section

2. 2. 2 described in the text.

2. 4. 3 scope of application and characteristics

The fuse circuit breaker is light in weight, small in size, easy to manufacture, low in cost, and has current limiting characteristics, and is suitable for power supply circuits that are operated infrequently. The disadvantage is that the spare parts must be automatically replaced immediately after each current interruption. It can only be used to break the circuit, and cannot be used to connect the circuit.

2. 5 PTC circuit breaker

2. 5. 1 structural principle

PTC current interrupter is a current-limiting type static micro interrupter without arc interruption. Its structural principle is to fill a common PTC thermosensitive element with a certain density of conductive particles in the middle of ordinary insulating materials (such as polyethylene). It is a conductor with a conductive link. When connected to the circuit, the current will generate a thermal effect through the interrupter. The thermal diffusion ability of the insulating material of PTC is stronger than that of the conductive material. The thermal diffusion of the insulating material will divide the conductive particles until the conductive link is blocked.

2. 5. 2 working principle

The working principle of a circuit breaker with a PTC circuit breaker is basically the same as that with a mercury circuit breaker. This section is described in 2.2.2.

2. 5. 3 scope of application and characteristics

PTC circuit breaker is simple in structure, light in weight and small in size. It has good current-limiting characteristics and can be statically arc-free blocking circuit. It is especially suitable for short circuit and DC circuit breaking. The disadvantage is that a certain heat recovery time is required after the current is cut off, and it cannot be frequently operated immediately, and can only be used to break the circuit, and cannot be used to connect the circuit.

2. 6 thyristor interrupter

2. 6. 1 structural principle

Thyristor current interrupter is a kind of static micro switch device without arc interruption. It is composed of thyristor without heat sink and its control circuit. Its structural principle is essentially the static arc-free switching principle of thyristor. The interrupter is the interruption of the natural zero crossing of the AC current. The working time in the interrupt switch is short, and does not exceed the half cycle of the power frequency current-10ms. In this way, the switching function of the thyristor without arc interruption can be brought into full play, and its interruption capacity can be increased by 5 to 10 times. However, the rated voltage and rated current of high-power thyristors are not high enough at present. High-power tubes have been developed and used at home and abroad, with a rated voltage of 8000V and a rated current of 3000A. Using the series-parallel structure principle can improve the interrupting capacity and Voltage level. Due to its short working time, large heat sinks are generally not needed, and it can be placed in insulating oil during high pressure or frequent operations.

2. 6. 2 working principle

During the opening and closing process, the cut-off switch equipped with a thyristor interrupter performs step-by-step operation according to program control. During the closing process, when the moving contact of the switch is closed to the initial closing position, the circuit breaker is only connected to the circuit and is not turned on. At this time, the thyristor control electrode is triggered and the circuit is activated after the circuit is connected. The contacts continue to close to the closed position, and the circuit breaker is shorted in the circuit, and it is ready for opening. In the opening process, the current in the circuit was automatically transferred to the current interrupter as soon as the semi-static contact of the switch was separated, and then the trigger voltage of the thyristor control pole was quickly and automatically turned off. After the AC current crosses zero automatically, the moving contacts will continue to separate to the post-opening position to safely isolate the power supply.

2. 6. 3 scope of application and characteristics

Thyristor interrupters have a very long life. Not only can they be statically disconnected without arcs, but also they can be connected statically without arcs, and they can be opened and closed very quickly. They can be used in power supply circuits that are operated frequently. However, its price is relatively expensive, and its ability to withstand short-circuit current is poor.

3 Design of contact unit

3.1 Introduction

3. 1. 1 basic structure of the contact unit

The structure of the contact unit is a bit like a knife blade of a three-phase isolating switch. Each phase has a moving contact and a set of static contacts. The stationary contact group has a stationary stationary contact, a movable semi-static contact, and a stationary transfer contact. The static contact is connected to the power supply side, the semi-static contact is connected to the load side through a soft connection, and a current interrupter is connected between the semi-static contact and the transfer contact. The moving contact is a strip-shaped double-piece gate knife connected to the operating lever. During the brake, the two ends of the blade clamp the three contacts of the static contact group. A steel plate and a pressure spring are mounted on the outside of the double blade, and the steel plates that are close to the static contacts at the outer ends of the two ends of the blade are magnetic locks. The steel plates are not shown in the following figure. It has two functions. On the one hand, under the pressure of the spring, through the lever ratio of the magnetic lock, the blade and the static contacts can maintain a good contact and generate a large contact pressure. On the other hand, the short-circuit current flows. Obsolete, because the steel plate is magnetized, a magnetic suction force can be generated, which acts on the blade to increase the contact pressure, thereby preventing short-circuit current from causing contact welding and preventing the blade from separating by itself. If its load current is required to be large, each phase can adopt the double-blade knife or multi-noise structure of the above-mentioned form.

3. 1. 2 Structure type of contact unit

The basic function of the contact unit in the interrupt switch is that the dynamic and static contacts can perform the operation of separating and closing the circuit, and also has the function of automatically transferring the loop current to the interrupter at the moment of opening and closing. According to its function of transferring current, it can be divided into single transfer type contacts and double transfer type contacts. The single transfer type contact unit is suitable for the interrupter of the micro interrupter. The double transfer type contact unit is suitable for the micro Circuit breaker. The pressure-resistant opening distance of the dynamic and static contacts can be divided into two structural forms of short opening distance and long opening distance. The insulation distance of short opening distance is generally not more than 125mm, and the long opening distance is generally greater than 125. The short-open distance contact unit is suitable for low-voltage and medium-voltage cut-off switches, and the long-open distance contact unit is suitable for medium-voltage and higher voltage cut-off switches. Then there are four types after combination: a. Single transfer short open distance contact unit, b, Single transfer long open distance contact unit, c, Double transfer short open distance contact unit, d, Double transfer long open distance contact unit.

3.2 2 single-shift short-open contact unit

The structure and principle of the single transfer short-open contact unit is shown in Figure 7, where 1 is a moving contact, 2 is a static contact, 3 is a semi-static contact, 4 is a transfer contact, Figure 7 (a) and Fig. 7 (c) is a front view of the moving contact and the static contact group, and Figs. 7 (b) and 7 (d) are left views thereof, respectively. In Fig. 7 (c), the front ends of the static contact and the semi-static contact are aligned on a straight line, and the front end of the transfer contact is about 3mm behind it. When the switch is closed, the moving contact and the static contact and the semi-static first. The contacts are closed, followed by the transfer contacts.

3. 3 Single Transfer Long Open Distance Contact Unit

The structure principle of the single-transfer long-open-distance contact unit is shown in Figure 8, which is basically the same as the single-transfer short-open-distance contact unit. The difference is that the shape of the transfer contacts is somewhat different, and the opening distance between the contacts is relatively large.

3. 4 double-shift short-open contact unit

The structural principle of the double-transferred short-open-distance contact unit is shown in Figure 9, which is basically the same as the single-transferred long-open-distance contact unit. However, the front end of the static contact and the transfer contact are aligned in a straight line. The front end of the semi-static contact is more than 30mm behind it. When the brake is closed, the moving contact is first closed with the static contact and the transfer contact. After closing, close the semi-static contact.

3. 5 double transfer long open contact unit

The structure of the double-transferred long-open-distance contact unit is shown in FIG. 10, which is basically the same as the double-transferred short-open-distance contact unit. The difference is that the front ends of the static contacts and the transfer contacts are aligned in a straight line, the semi-static contacts are farther back, and the distance between the contacts is larger. 4 Design scheme of switch mechanism

4.1 Introduction

4. 1. 1 Design of the operating mechanism

The operating mechanism can be designed as an operating mechanism with different strokes according to the requirements of the voltage level. Low-pressure actuators with short strokes are required. The stroke is tentatively within 40mm. Simple E-type or U-type or solenoid solenoids can be used as the power source for operation. A medium-stroke operating mechanism is required for medium pressure, and its stroke is tentatively set at 40 ~ 125mm. A simple solenoid-type electromagnet or energy storage spring can be used as the power source for operation. The voltage level above medium voltage requires a long-stroke operating mechanism. Its stroke is tentatively set to 125mm or more. Energy storage springs or electric motors or hydraulic mechanisms can be used as the operating power source. If one actuator cannot meet the needs, it can also be designed as a dual actuator. The single-acting cut-off switch is controlled by one operating mechanism to operate the three-phase moving contact in one body. The double-acting cut-off switch needs to be controlled by another operating mechanism to operate the three-phase semi-static contact in one body.

4. 1. 2 Structure type of switch mechanism

According to the short open distance and long open distance of the contact unit, the switch mechanism requires two types of structures: single-acting and double-acting. The contact units are divided into single-transfer type and double-transfer type. Four types: a, single operation single transfer type, b, double operation single transfer type, c, single operation double transfer type, d, double operation double transfer type.

4. 2 Single-action single-transfer type cut-off switch

4. 2. 1 Structural principle

The single-phase structure principle of the single-acting single-transfer interruption switch is shown in Figure 11. The contact unit in the figure adopts the structure type of the single-transfer short-open contact unit shown in Figure 7. In the figure, 1 is a moving contact, 2 is a static contact, 3 is a semi-static contact, 4 is a transfer contact, 5 and 6 are operating levers, 7 and 8 are electromagnetic locks, and 9 is an E-type opening solenoid. , 16 is a pressure spring, 11 is a soft connection, 12 and 14 are terminals, 13 is a circuit breaker, and 15 is a hard connection. The static contact 2 is connected to the power supply side, and the terminal 12 is connected to the load side. A closing spring is sleeved on the middle core of the E-type electromagnet 9, and the closing spring is stored with energy when the electromagnet is attracted to prepare for closing. Depending on the voltage level and the required operating stroke, a solenoid solenoid or an energy storage spring can be used as the operating power source.

The cut-off switch has three stable states during operation, as shown in Figure 12, where Figure (a) is the opening position, Figure (b) is the closing position, and Figure (c) is the initial breaking position. In the figure, 1 is a moving contact, 2 is a static contact, 3 is a semi-static contact, 4 is a transfer contact, 5 and 6 are operating levers, 7 and 8 are electromagnetic locks, and 16 is a compression spring.

4. 2. 2 working principle

When the cut-off switch receives the closing command, as shown in Figures 11 and 12, the electromagnetic lock 7 is unlocked by power on, and the operating lever 5 pushes the moving contact 1 to close the static contact 2 and the static contact 2 quickly under the elastic force of the closing spring. In the semi-static contact 3, it is then closed to the transfer contact 4 and continues to push the semi-static contact 3 to the closed position shown in FIG. 12 (b). The electromagnetic lock 8 automatically locks the operating lever 6, and the electromagnetic The lock 7 is automatically powered off by the normally closed contact of the auxiliary switch. This The current interrupter 13 has been short-circuited in the circuit and is ready for analysis. The moving contact 1 is mainly fixed to the static contact group by the clamping force on both sides of the blade, and of course there is a closing spring. Little residual thrust. When opening, the opening solenoid 9 is energized to attract the armature. Under the action of a large electromagnetic force, the operating lever 5 pulls the contact 1 to be quickly separated to the initial opening position shown in FIG. 12 (c). It is automatically locked, and the opening solenoid 9 is automatically powered off by the normally open auxiliary contact of the electromagnetic lock 7. After the circuit breaker 13 automatically disconnects the circuit, the control unit delays energizing the opening electromagnet 9 again, and at the same time energizes the electromagnetic lock 7 to unlock it. The operating lever 5 continues to pull the contact 1 to separate it to Fig. 12 (a) The opened position shown is automatically locked again by the electromagnetic lock 7, and at the same time, the open-circuit power generator 9 is automatically powered off. Immediately after the electromagnetic lock 8 is turned on and unlocked, the semi-static contact 3 moves to the opening position shown in FIG. 12 (a) under the spring thrust, and the electromagnetic lock 8 is automatically powered off by the auxiliary contact. The opening solenoid 9 stores energy for the closing spring at the same time as the opening, and prepares for the next closing.

4. 3 double-acting single-transfer interruption switch

4. 3. 1 structural principle

The single-phase structure principle of the double-acting single-transfer cut-off switch is shown in Figure 13, and the components in the figure are basically the same as those shown in Figure 11. The difference is that the contact unit adopts the structure type of single transfer long opening distance shown in FIG. 8, and at the same time, another E-type opening solenoid 10 is connected to the operating rod 6 of the semi-static contact 3. Of course, the electromagnets 9 and 10 can each adopt solenoid type, E-type or U-type electromagnets, or energy storage springs, electric motors, hydraulic mechanisms, etc., as operating power sources according to the voltage level and the requirements of the operating stroke.

The cut-off switch has three stable states during operation, as shown in Figure 14. In the figure, (a) is the opening position, (b) is the alarm position, and (c) is the initial opening position.

4. 3. 2 working principle

The working principle of the interrupt switch is described with reference to FIGS. 13 and 14. When closing, the electromagnetic lock 7 is instantly energized and unlocked. The moving contact 1 is quickly closed to the closing position shown in FIG. 14 (b) under the thrust of the closing spring in the electromagnet 9, and the electromagnetic lock 7 is switched by an auxiliary switch. The normally closed contact is automatically powered off. The moving contact 1 closes the static contact 2, the semi-static contact 3 and the transfer contact 4 and short-circuits the circuit breaker 13 in the circuit to prepare for the opening. When opening, the opening electromagnet 10 is energized to attract the armature, and the operating lever 6 pulls the semi-static contact 3 minutes away from the initial opening position shown in FIG. 14 (c). The operating lever 6 is automatically locked by the electromagnetic lock 8. At the same time as the electromagnet 10 is initially opened, it has stored energy for the compression spring sleeved on its middle core. After the circuit breaker 13 automatically breaks the circuit, the control unit delays the opening solenoid 9 to energize the suction core, and the operating lever 5 pulls the contact 1 to separate to the opening position shown in FIG. 14 (a). The operating lever 5 is automatically locked by the electromagnetic lock 7, and the normally closed contact of the auxiliary switch causes the opening electromagnet 9 to automatically power off. Next, the normally open contact of the auxiliary switch unlocks the electromagnetic lock 8 instantaneously, and the semi-static contact 3 also returns to the opening position shown in FIG. 14 (a) under the thrust of the energy storage spring in the electromagnet 10, as shown in FIG. The secondary closing is ready.

4. 4 Single-action double-transfer interruption switch

4. 4. 1 Structural principle

The single-phase structure principle of the single-acting double-transfer cut-off switch is shown in Figure 15. The contact unit in the figure uses The structure of the double-transferred short-open contact unit shown in FIG. 9. In the figure, 1 is a moving contact, 2 is a static contact,

3 is a semi-static contact, 4 is a transfer contact, 5 is an operating lever, 7 is an electromagnetic lock, 9 is a solenoid opening solenoid, 12 and 14 are terminals, and 13 is a circuit breaker. The static contact 2 is connected to the power supply side, and the terminal 12 is connected to the load side. One end of the core of the solenoid solenoid 9 is pressed against a closing spring. When the solenoid opens, the closing core stores energy to the closing spring to prepare for closing. It can also use E-type electromagnets or energy storage springs, electric motors, hydraulic mechanisms, etc. as the power source for operation according to the requirements of voltage level and operating stroke.

The cut-off switch has four stable states during operation, as shown in Figure 16. In the figure, (a) is the opening position, (b) is the closing position, and (c) is both the initial opening position and the initial closing position.

4. 4. 2 working principle

The working principle of the cut-off switch is described with reference to FIGS. 15 and 16. When the solenoid is closed, the electromagnet 7 is instantly energized and unlocked. When the operating lever 5 pushes the movable contact 1 to close quickly to the initial closing position shown in FIG. 16 (c) under the elastic force of the closing spring, the operating lever 5 It is automatically locked by the electromagnetic lock 7 which has been powered off. At this time, the moving contact 1 is closed with the static contact 2 and the transfer contact 4, and the current interrupter 13 is connected to the circuit. After the circuit is automatically connected, the control unit delays the electromagnetic lock 7 for an instant to unlock it. The moving contact 1 continues to close to the closing position shown in FIG. 16 (b). At this time, the moving contact and the static contact group are all closed, and the circuit breaker 13 is short-circuited in the circuit, and it is ready for splitting. When the brake is opened, the electromagnet 9 is energized to attract the moving iron core. Under the action of a large electromagnetic force, the operating lever 5 quickly pulls the contact 1 to be separated to the initial opening position shown in FIG. 16 (c). The lever 5 is automatically locked by the electromagnetic lock 7 which has been powered off, and the electromagnet 9 is automatically powered off. At this time, the moving contact 1 and the semi-static contact 3 are completely separated. After the circuit breaker 13 automatically breaks the circuit, the control unit delays the electromagnetic lock 7 to be instantaneously energized and unlocked, and at the same time, the electromagnet 9 is automatically energized and activated again When the iron core and the moving contact 1 continue to separate to the opening position shown in FIG. 16 (a), the operating lever 5 is automatically locked by the electromagnetic lock 7 which has been powered off, and the electromagnet 9 is automatically powered off. At this time, the moving contact 1 is completely separated from the static contact 2 and the transfer contact 4, so that the circuit breaker can safely isolate the power supply. During the opening, the electromagnet 9 absorbs the moving iron core and stores energy for the closing spring, which is ready for the next closing. '

4.5 Double-operated double-transfer cut-off switch

4. 5. 1 Structural principle

The principle of the single-phase structure of the double-acting double-transfer interruption switch is shown in Figure 17, and the components in the figure are basically the same as those shown in Figure 13. The difference is that the contact unit adopts the structure form of double transfer long opening distance shown in FIG. 10.

The cut-off switch has four stable states during operation, as shown in Figure 18. In the figure, (a) is the opening and closing position, (b) is the closing position, and (c) is both the opening and closing position.

4. 5. 2 Working principle

The working principle of the interrupt switch is described with reference to FIGS. 17 and 18. When closing, the electromagnet 7 is instantly energized and unlocked. When the moving contact 1 is quickly closed to the initial closing position shown in FIG. 18 (c), the static contact 2 and the transfer contact 4 are closed, and the interrupter 13 is closed. Connected to the circuit. After it is automatically connected to the circuit, it is extended by the control unit. When the electromagnetic lock 8 is turned on for a moment, the semi-static contact 3 is immediately closed to the moving contact 1, that is, the closing position shown in FIG. 18 (b), and the circuit breaker 13 is short-circuited in the circuit. Ready for opening. When opening, the opening electromagnet 10 is energized, so that the semi-static contact 3 is quickly separated to the initial opening position shown in FIG. 18 (c). After the circuit breaker 13 automatically breaks the circuit, the control unit delays the opening to the opening. The brake solenoid 9 is energized, and the movable contact 1 is separated to the opening position shown in FIG. 18 (a), which is ready for the next closing.

4. 6 Design Scheme of Locking Device

The locking device used in each of the above-mentioned operating mechanisms is a dedicated electromagnetic lock, and a permanent magnet lock with a superior performance and a faster unlocking speed can also be used. The structural principles are introduced below.

4. 6. 1 Structural principle of electromagnetic lock

The electromagnetic lock consists of a small solenoid electromagnet, a small spring, a small lock rod connected to the iron core, and two pairs of normally open and normally closed auxiliary contacts. The structure principle is shown in Figure 19. In the figure, 21 is a static iron core, 22 is a coil, 23 is a moving iron core with a small lock lever, 24 is a small spring, and 25 is an auxiliary contact. When the coil 22 is not energized, the small spring 24 pushes the moving iron core 23 and its small lock lever and can be automatically inserted into the lock hole of the locked mechanism. The normally open contact on the auxiliary contact opens and the normally closed contact closes. When the coil 22 is energized, the moving iron core 23 is sucked into the tube and compresses the small spring 24. The moving iron core pulls the small lock lever to release the lock, releases the locked mechanism, the normally open contact on the auxiliary contact closes, and the normally closed contact opens. If needed, better position sensors can be used instead of auxiliary contacts.

4. 6. 2 Structural principle of permanent magnet lock

The single-coil single-lock permanent magnet lock consists of a small solenoid with permanent magnets. There is a small section of iron core in the operating lever of the locked mechanism. The structure principle is shown in Figure 20 (a). The iron core, 32 is a coil, 33 and 34 are permanent magnets, and 35 is a moving iron core connected to an operating lever. When the operating lever moves, when this small section of iron core 35 enters the small solenoid, the operating lever is automatically locked by the magnetic attraction of the permanent magnet. If it is necessary to release the lock, the coil 32 of the small solenoid is energized, the electromagnetic force will cancel the permanent magnet suction, and the operating lever will be automatically released. The operating lever can also have auxiliary contacts, and position sensors can be used instead of auxiliary contacts. If the joystick needs to be locked at two or more different positions, a small core of iron can be placed in each position on the joystick to make a single coil double lock or a single coil multiple lock. Permanent magnet lock. The structure and principle of the single-coil and double-lock permanent magnet lock are shown in Figure 20 (b). In the figure, 35 and 36 are two small moving iron cores connected to the operating lever. When the two moving iron cores in the operating lever are respectively When moving into the small solenoid, it can be locked separately in these two positions. It can also be designed as a permanent magnet lock with double coils and double locks. The structure principle is shown in Figure 20 (c). When the moving core 35 in the operating lever moves to the position of the coil 32, it is quickly locked. If the operating lever continues to move after the coil 32 is turned on and unlocked, the moving core 35 can be quickly locked when it enters the position of the coil 37.

4. 7 Design scheme of permanent magnet operating mechanism

During the opening and closing operations of the electromagnet mechanism used by each of the above-mentioned operating power sources, when the operating lever of the moving contact and the semi-static contact is moved to a specified position, a special locking device is required for locking. Here, several electromagnetic operating mechanisms with permanent magnet locks are designed, which have fewer parts and better matching performance. They can replace the above operating mechanisms in different situations.

4. 7. 1 Structural principle of monostable permanent magnet actuator

The structure and principle of the monostable permanent magnet operating mechanism is shown in Fig. 21, and two permanent magnets 41 and 42 are provided in the static iron core 44 of the solenoid electromagnet as the locking device of the opening position. The closing position of the mechanism. When opening, the opening coil 43 is connected with direct current, and the attracting core 45 pulls the operating lever 46 to drive the moving contact or semi-static contact to open and compress the closing spring 47 to store energy. When the iron core 45 is attracted to the position of the opening / closing terminal, it is automatically locked by the permanent magnets 41 and 42, the opening coil 43 is powered off, and the opening is completed. When it is necessary to unlock the closing alarm, the closing coil 43 is automatically unlocked by applying a reverse current. The opening coil 43 is powered off and the closing is completed.

4. 7. 2 Structural principle of bistable permanent magnet actuator

The structural principle of the bistable permanent magnet operating mechanism is shown in Fig. 22. In the middle part of the static iron core 55 of the double-coil solenoid electromagnet, two permanent magnets 51 and 52 are set as the two positions of opening and closing. The locking device of the device is shown in the figure. When opening, the opening coil 53 is connected with direct current, which can automatically unlock the permanent magnets 51 and 52. At the same time, the moving iron core 56 is pulled and an operating rod 57 made of non-magnetic material is pulled to drive the contact to be opened. At the brake terminal position, the moving iron core 56 is automatically locked by the permanent magnets 51 and 52, the opening coil 53 is powered off, and the opening is completed. When it is necessary to unlock the closing, the closing coil 54 is supplied with direct current, which can automatically unlock the permanent magnets 51 and 52, and at the same time attract the closing iron core 56 to push the operating lever 57 and the contacts to close, and move to the closing end position The moving iron core 56 is automatically locked at the closing position by the permanent magnets 51 and 52, the closing coil 54 is powered off, and the closing is completed.

4. 7. 3 Structural Principles of Tristable Permanent Magnet Operating Mechanism

The structural principle of the three-steady-state permanent magnet operating mechanism is shown in Fig. 23. In the middle part of the static iron core 65 of the double-coil solenoid electromagnet, two permanent magnets 61 and 62 are set as the initial opening and closing gates. The locking device at the three positions of initial closing and the closing position is shown in the figure. During the initial opening, a direct current is applied to the coil 64, the moving iron core 66 is pulled, and the operating lever 67 is pulled to drive the contacts to open, and the closing spring 68 is compressed to store energy. When the moving iron core 66 is attracted to the middle position, it is automatically locked by the permanent magnets 61 and 62, the coil 64 is powered off, and the opening is suspended. When it is necessary to unlock and continue to open, the direct current is applied to the coil 63, which can automatically unlock the permanent magnets 61 and 62. At the same time, the moving iron core 66 is pulled again and the operating lever 67 is pulled to drive the contacts to continue to open and continue to compress and close. The spring 68 stores energy. When the moving iron core 66 is attracted to the opening terminal position, it is automatically locked again by the permanent magnets 61 and 62, the coil 63 is powered off, and the opening is completed. When it is necessary to unlock and close, the coils 63 and 64 can be automatically unlocked with a reverse current at the same time. When the moving core 66 moves to the middle position, the coils 63 and 64 are powered off, and the moving core is again turned by the permanent magnet 61. And 62 are automatically locked and closing is suspended. When unlocking is required to continue closing, a reverse current is applied to the coil 64 to automatically unlock and continue closing. The coil 64 is powered off and the closing is completed.

4. 7. 4 Structural principle of four steady-state permanent magnet operating mechanism The structural principle of the four-steady-state permanent magnet operating mechanism is shown in FIG. 24. At the two intermediate parts of the static iron core 78 of the three-coil solenoid electromagnet, permanent magnets 71, 72, 73, and 74 are respectively set as closing. The locking devices in the four positions of the opening, opening, opening and closing are shown in the figure. When the coil is initially opened, the coil 76 is continuously energized to unlock the moving iron core 79. At the same time, the coil 77 is energized to attract the moving iron core 80 and pull the operating rod 81 made of non-magnetic material to drive the contacts to be opened. When the moving iron core 80 is attracted to the closed position of the coil 77, it is automatically locked by the permanent magnets 73 and 74, the coils 76 and 77 are respectively powered off, and the opening is suspended. When it is necessary to unlock and continue to open, the coil 77 passes a reverse current to unlock the moving iron core 80, and at the same time, the coil 75 passes the DC current to attract the moving iron core 79, and continues to pull the operating lever 71 to drive the contact to continue to open. When the moving iron core 79 is attracted to the opening terminal position, it is automatically locked again by the permanent magnets 71 and 72, the coils 77 and 75 are respectively powered off, and the opening is completed. When it is necessary to unlock and close, the coil 75 is energized to unlock the movable lock core 79, and at the same time, the coil 77 is energized to attract and close the movable iron core 80, and push the operating lever to drive the contact to close. When the moving iron core 80 is attracted to the closed position of the coil 77, it is automatically locked by the permanent magnets 73 and 74, the coils 75 and 77 are respectively powered off, and the closing is suspended. When unlocking is required to continue the operation, the coil 77 passes a reverse current to unlock the moving iron core 80. At the same time, the coil 76 is energized to attract the moving iron core 79 and push the operating lever to drive the contact to continue closing. The moving iron core 79 is attracted to When the closed position of the coil 76, that is, the closing end position, is automatically locked by the permanent magnets 71 and 72 and 73 and 74, the coils 76 and 77 are respectively powered off, and the closing is completed.

4. 8 Design considerations of anti-bounce lock for semi-static contact

4. 8. 1 Design considerations when using electromagnetic lock on semi-static contact

When an electromagnetic lock is used on the semi-static contact, as shown in Figs. 11 and 13, the semi-static contact 3 is not locked when it is ready to be closed, and it is only pushed by this by the back pressure spring. The moment when the moving contact 1 and the semi-static contact 3 are in contact when they are closed, it may cause the semi-static contact 3 to undergo a back-and-forth telescopic bounce motion, which may cause an arc. This is not allowed. There are two solutions: One is to open a small lock hole on the operating lever 6 of the lock position of the electromagnetic lock 8 in the above two figures, so that the electromagnetic lock 8 can automatically lock the operating lever 6 and the semi-static contact. The head 3 can eliminate the bounce movement of the semi-static contact during the initial contact. However, it is necessary to energize the electromagnetic lock 8 during unlocking. It takes a certain amount of time. In this way, there will be some unfavorable factors that respond to the fast opening when the short circuit is opened, which may delay several milliseconds to tens of milliseconds. time. Another solution is to install an anti-bounce automatic locking device on the operating rod 6 or the one-phase semi-static contact 3, and if necessary, one can be added to the semi-static contact of each phase.

4. 8. 2 Structural principle of anti-bounce automatic locking device

The structural principle of the anti-bounce automatic locking device is shown in Figure 25. The position shown in the figure and the arrangement of the static contact groups of each phase are installed vertically. Only an automatic locking device can be installed at the semi-static contact of the middle phase. In the figure, 91 and 92 are the blades clamped on both sides of the moving contact, 90 is the insulated plug on the outside, and 5 is the operating lever on the moving contact. 3 is a semi-static contact, 6 is its operating lever. 93 and 94 are two insulated sliding locks on the automatic locking device, 95 and 96 are compression springs on both sides, and 97 is an insulating base. Active contact plug When the static contact unit is closed, the blades 91 and 92 on both sides of the moving contact are first inserted and clamped to the semi-static contact 3 which has been locked by the automatic locking device, to prevent the semi-static contact from bouncing. The phase and half static contacts are connected to the same operating lever 6, so no contact bounce occurs in three phases. Next, the insulating plugs 90 on both sides of the moving contact are inserted into the insulating sliding locks 93 and 94 on the locking device. As the closing continues to be inserted, the sliding lock can be automatically unlocked at the same time. Quick response at opening is ready. When the semi-static contact is reset to the ready-to-close position after opening, the semi-static contact 3 can automatically lift the sliding locks 93 and 94 and be automatically locked, preparing for the anti-bounce when closing.

4. 8. 3 Design considerations when using permanent magnet lock on semi-static contact

When the permanent magnet lock on the semi-static contact is used, a permanent magnet lock with a double locking position can be adopted. According to the distance between the two required locking positions, a single coil double locking permanent magnet lock or a double coil double locking permanent magnet lock can be selected respectively. See Figure 20 (b) and Figure 20 (c). Setting a suitable moving iron core at the appropriate position of the operating lever of the semi-static contact can automatically lock the ready-to-close position and the initial opening position of the semi-static contact respectively, which can prevent the semi-static contact from bouncing when closing. Can guarantee the step-by-step operation of program control when opening. Of course, the single-position permanent magnet lock can also be used on the semi-static contact, as shown in Figure 20 (a), which is used to lock the initial opening position. However, at this time, an anti-bouncing automatic locking device needs to be installed, as shown in the structure shown in Figure 25.

4. 8. 4 Design considerations when semi-static contact operation adopts permanent magnet operating mechanism

For the operation of the semi-static contact of the double-actuated mechanism's cut-off switch, if a permanent-magnet operation mechanism is to be used, a bistable permanent-magnet operation mechanism can be directly used, as shown in the structure shown in FIG. The need for bounce of semi-static contacts during braking and the step-by-step operation of program control during opening It is also possible to use a monostable open permanent magnet operating mechanism, as shown in the structure shown in Figure 21, but it is necessary to add an anti-bounce automatic lock or a single-lock permanent magnet lock.

4. 9 Design of the contact stroke

The cut-off switch invented in this paper can meet the needs of AC / DC power grids of various voltage levels, and can also meet the requirements of breaking various load currents. However, it is not very ideal for short-circuit current-limiting interruption. A current-limiting switch will be designed in another article, which can be used for current-limiting interruption of short-circuit current. In the power system below 10KV, the medium in the contact unit of the interrupt switch uses ordinary air, which can replace the existing medium-voltage circuit breaker, and replace the large-capacity low-voltage circuit breaker and contactor. As the voltage level continues to increase, the requirements for insulation and withstand voltage become higher, the contact opening distance becomes larger and larger, and the stroke when the moving contact opens and closes becomes larger. When designing the operating mechanism, the operating strokes of various power sources have certain restrictions. For example, the moving strokes of the moving iron cores of E-type and U-type electromagnets are relatively short. The moving stroke of the moving iron core can be longer than that of the E and U types, and the moving stroke of the spring, the motor and the hydraulic operating mechanism can be longer than that of the solenoid type electromagnetic operating mechanism. Then there will be a problem of design cooperation between the contact stroke and the movement stroke of the operating mechanism. Two simple methods for changing the contact stroke are introduced below. Through these two methods, the interrupt switch can be applied to the circuit of ultra-high voltage and ultra-high voltage. The higher the voltage level, the better the superiority of the interrupt switch can be shown. 4. 9. 1 Method of Enlarging Contact Stroke

When the contact opening distance is relatively large, the stroke is long, and the moving stroke of the operating mechanism is short, such as the moving iron core of the E-type electromagnet. At this time, the moving contact cannot be directly connected to the operating lever of the moving iron core. Otherwise, the stroke of the moving contact is restricted and will be as short as the pull-in stroke of the moving core. A simple way to solve the problem is to connect a lever-type lever-driven lever or shaft between the moving contact and the moving iron core. The adjustment of the force arm or the torque can expand the contact stroke, making them both Match the sport stroke.

4. 9. 2 Ways to shorten contact travel

When the voltage level is high and the insulation distance between the phases and the contact distance are large, the three-phase contacts can be placed in an insulating medium, such as insulating oil, SF ₆ or other medium. At this time, the design principle of the selection medium is obviously different from that of the traditional switch. The contact medium of a traditional switch is mainly designed with its arc extinguishing performance in mind when designing and selecting it, and its insulation performance is considered next. The contact medium of the cut-off switch mainly considers its insulation performance when designing and selecting, and there is no special requirement for its arc extinguishing performance.

4. 10 Design considerations for auxiliary switches

The auxiliary switch of the cut-off switch can be provided with a pair or two pairs of normally open and normally closed contacts at the opening and closing positions at both ends of the operating lever, as shown in Figure 26. In the figure, the operating lever 5 is in the closing position, and its link can make the contact HW of the auxiliary position auxiliary switch act; when the operating lever is moved to the left to the opening position, the contact FW of the opening position auxiliary switch can be actuated. . For the two operating levers of the double operating mechanism, auxiliary switches 1FW, 1HW and 2FW, 2HW of the opening and closing positions of the moving contact and the semi-static contact can be respectively set as required. The contacts of these auxiliary switches can also be replaced with better position sensors.

5 Design scheme of control unit

5. 1 Type of control unit

The control unit can be divided into four kinds of operation control principles according to the type of switch mechanism: a. Single operation single transfer control, b. Double operation single transfer control, c. Single operation double transfer control, d, Double operation double transfer control.

5. 2 Control Principle

The principle of single operation and single transfer control is shown in Figure 27, the principle of double operation and single transfer control is shown in Figure 28, the principle of single operation and double transfer control is shown in Figure 29, and the principle of double operation and double transfer control is shown in Figure 30 Show. In the figure: 1RD, 2RD, 3RD, 4RD are fuses, FA and HA are opening and closing buttons, HW, 1HW, 2HW are closing position auxiliary switch contacts, FW, 1FW, 2FW are opening position auxiliary switch contacts. DS, IDS, 2DS are electromagnetic locks, FC, 1FC; and 2FC are opening contactors, FQ, 1FQ, and 2FQ are opening solenoid coils, ZJ, 1ZJ, and 2ZJ are intermediate relays, and SJ is a time relay. The control power bus and switching power bus shown in the figure are both 220V DC power, and 220V AC power can also be used.

The above control principle adopts relay control, and it can also adopt more superior PC control to compile a simple fool-type program control unit.

5. 3 working principle

The working principle of the control circuit shown in Figure 27 ~ 30 and the current interruption described in this article 4. 2 ~ 4. 5 The working principle of the switch is basically the same, and the action process and operation sequence of the relay are the same. The control circuits shown in Figures 27 and 28 are suitable for use with mercury, sodium, fuses and PTC interrupters. The control circuits shown in Figures 29 and 30 are suitable for use with thyristors, micro-actions, seesaws, Electrically and magnetically controlled interrupters. The various types of cut-off switches designed by the present invention are suitable for opening and closing control of power lines with low, medium, high, ultra, and extra-voltage levels and various system capacities, respectively, and can meet the needs of modernization of power grids. .

6 Two rare examples of misuse

6. 1 At 8:35 on April 11, 1959, the watchman of the substation of Lanzhou Fertilizer Factory mishandled and used the PB-6 / 1000 disconnector to manually remove the 2500KW large motor that was running at full load, but it was safe and sound. No abnormalities occurred.

6. 2 On XX, X, 1968, the watchkeeper of the substation of Dalian Chemical Plant mishandled and switched on the 625KW large motor with the PB-6 / 400 type disconnector. No abnormality occurred, and the motor operated as usual.

These two misoperation accidents did not cause arcing to cause short circuit accidents. It shows that during the opening or closing process, when the three-phase brake blades of the disconnector are separated, they happen to catch up with the zero-crossing moments of the three-phase AC power, respectively, and the arc-free interruption or arc-free connection is performed. Although it was an accidental misoperation accident, it fully proved the fact that arc-free interruption is an objective existence. The present invention is based on this one-ten-thousandth chance, to strive for perfect reliability, and after 33 years of unremitting efforts, he has invented the ideal interrupter switch day and night.

Brief description of the drawings The best mode for carrying out the invention

Industrial applicability

Claims

Rights request

1. A current interrupter, which is characterized in that the current interrupter is responsible for the instantaneous current-carrying task of opening and closing the circuit during the opening and closing of the interrupt switch, and the working time is very short. Some current interrupters are only Within 10ms, some can be within tens of ms. Therefore, its current-carrying cross-section and volume are very small. In fact, it is a micro-switching device (which can switch on and off the circuit) or a micro-current-cutting device (which can only switch off the circuit). There are arc extinguishing and arc extinguishing. Micro-switching devices include thyristor interrupters, micro-motion interrupters, seesaw interrupters, electronically controlled interrupters, and magnetically controlled current interrupters. Micro-current interrupters include mercury interrupters, sodium interrupters, and fuses. Wire interrupters and PTC (Positive Temprature Coeffcient) interrupters can meet the needs of different voltage levels and breaking capacity, respectively.

2. A switch contact unit, which is characterized in that the contact unit can not only ensure the reliable power supply during the operation of the disconnect switch, but also can break or switch on the current under high-speed dynamic conditions during opening and closing, and quickly transfer to the interrupt Static or easy interruption or conduction in the flow device. This unique function of automatically and quickly transferring current when switching on and off can be implemented in simple step-by-step operations using the structural forms of moving contacts, static contacts, semi-static contacts, and transfer contacts. Can eliminate electrical wear on contacts, solve electrical life and manufacturing difficulties. When equipped with a miniature interrupter-type interrupter, the contact unit can be quickly closed with a micro-arc or a small arc when it is closed, and arc-free interruption can be performed during the interval; The opening and closing of the contactor and contact unit can be operated without arc. Then the electrical life of the contact unit is very long and the manufacturing cost is very low.

3. An electrical contact method, characterized in that the contact unit uses a plug-in contact method such as an isolating switch, and the contact pressure is the clamping force and the magnetic lock force of the springs on both sides of the blade. The operating force during opening and closing is very small, it is only the clamping force multiplied by a small friction coefficient. It does not require the closing pressure of thousands of Newtons in the butt contact method like a vacuum switch, and can operate under heavy load. Reduced to light or no-load operation, which can eliminate contact bounce when closing, solve the problem of butt-type closing pressure, can reduce the strong mechanical impact during opening and closing, and effectively extend the mechanical life of the switch.

4. A switching mechanism, characterized in that the switching mechanism cancels or simplifies the transmission mechanism and the contact stroke mechanism, greatly reduces the transmission chain, and directly applies the operating power source to the contacts. According to the requirements of voltage level and contact opening distance, single operating mechanism or double operating mechanism is adopted. The operating force is decomposed, and its operating force, operating power, and power consumption are all very small, which is only 1/3 to 1/10 of the existing circuit breaker, so its volume and manufacturing cost are small. During the opening operation, the initial opening The response speed is very fast, and the speed when continuing to open is relatively slow, which eliminates the impact force and bounce when opening. In some switching mechanisms, the semi-static contact is equipped with an anti-bounce automatic locking device, which can effectively prevent the telescopic bounce when the upper semi-static contact is closed. The switch mechanism also uses a magnetic lock or a permanent magnet lock. Some operating power sources can also use a permanent magnet operating mechanism with a locking device, which can perform the lock control during step-by-step operation. It automatically locks. And the speed of electric unlocking is very fast, the switch mechanism is simple and light, the operation is reliable, and the life is long.

5. A control unit, which is characterized in that the control unit adopts a simple relay control or a low-grade PC control according to the function of the breaker circuit. The control of the interrupter for the micro-interrupter device is a three-step program control of closing, primary opening and sub-division; the control of the interrupter for the micro-switching device is initial closing, closing, and opening. There are four steps of program control. The complex, fast, accurate, reliable, and high-precision intelligent control is reduced to a simple, low-speed, fool-proof low-level fool-type control. Its simple structure and low cost make it possible to solve the problem of control accuracy. It is applied to the control design of AC short-circuit current. When a current-limiting interrupter is used, its control setting time, detection response and transfer current time are very short. It can be controlled within 2ms, and its control unit must adopt fast response. PC control. When a non-current-limiting interrupter is used, the control design for the short-circuit current far from the power plant requires a delay of about 45ms from the moment of the short-circuit before transferring the current to the interrupter in time; for the short-circuit current near the power plant Control design requires a delay of about 150ms. The specific delay time can be calculated according to the parameters of the specific circuit. The decay time of the maximum transient component of the short-circuit current can be determined to determine the time when the first zero crossing of the current occurs after the short-circuit. It can control the interrupter to transfer the current and break the circuit when the transient component of the short-circuit current decays to zero crossing. It can ensure that the non-current-limiting interrupter has the shortest working time and the smallest current-carrying cross-section and volume. You can use relay control or PC control.

6. The switching mechanism according to claim 4, wherein one mechanism operates the contact and the other mechanism operates the semi-static contact. When operating between the opening and closing, it can not only cooperate with the automatic transfer of current in an orderly manner, but also decompose the operating force to reduce the manufacturing difficulty. It can also meet the requirements of long strokes, large opening distances and high voltage levels.

7. The switch mechanism according to claim 4, characterized in that the electromagnetic lock is composed of a small solenoid electromagnet, a small spring, a small lock rod connected to the iron core, and two pairs of normally-closed auxiliary contacts. Make up. When the coil is not energized, the small spring pushes the moving iron core and its small lock lever into the lock hole of the locked mechanism for automatic locking; when the coil is energized, the moving iron core is attracted and the small lock lever is pulled to release the lock. Can release the locked mechanism relatively quickly.

8. The switch mechanism according to claim 4, wherein the permanent magnet lock is composed of a small solenoid with a permanent magnet, and a small section of iron core is included in the operating lever of the locked mechanism. When the joystick moves, when this small section of iron core enters the small solenoid, it is automatically locked by the magnetic attraction of the permanent magnet. If it is necessary to release the lock, the coil of the small solenoid is energized, and its electromagnetic force will cancel the permanent magnet suction, and the operating lever will be released very quickly. This is a single coil single lock permanent magnet lock. It is also possible to set a small section of iron core in each of two or more different suitable positions of the operating lever, which can be made into a single-coil double-lock or multi-lock permanent magnet lock. It can also be designed as a permanent lock with double coils and double locks. When the core of the operating lever enters a suitable position of one of the coils, it will be automatically locked. The coil can be quickly released when the coil is energized. The other coil will also be automatically locked when it is in the proper position.

9. The switching mechanism according to claim 4, characterized in that the permanent magnet operating mechanism is a tri-stable or quad-stable permanent magnet operating mechanism. The tri-stable permanent magnet operating mechanism can perform the opening and closing operations of the automatic magnetic lock in three positions of initial opening, opening and closing. The four-steady-state permanent magnet operating mechanism can perform the opening and closing operations of the automatic magnetic lock at the four positions of initial opening, opening and closing, and closing. Its structure and working principle are basically the same as the existing monostable or bistable permanent magnet operating mechanism.

10. The switch mechanism according to claim 4, characterized in that an anti-bounce automatic locking device is provided with a mechanism capable of automatically locking at the root of the semi-static contact, and an automatic unlocking mechanism is provided outside the movable contact. Plug. During the opening and closing process, automatic locking and automatic release can be performed, which can effectively prevent the telescopic bounce of the semi-static contact.