CN103515956A - Voltage switching automatic paralleling device - Google Patents

Abstract

The invention discloses an automatic parallel device for voltage switching, which comprises three voltage transformers respectively connected to A, B and C of a three-phase AC power supply, and voltage secondary circuits connected in parallel to the three voltage transformers respectively. 3 low-voltage relays; the normally open nodes ①② of the 3 low-voltage relays are connected in parallel to the starting coils of the voltage parallel relay 3YQJ in series; the normally closed nodes ③④ of the 3 low-voltage relays are connected in series to the starting coils of the intermediate relay 1ZJ in sequence , to realize the isolation of the primary and secondary voltages; 1ZJ normally open nodes (11) (12) are connected in series with the 1ZK normally open auxiliary nodes (11) (14) of the air switch, and then connected in parallel with the auxiliary nodes of the bus tie isolation switch and switch After that, they are respectively introduced into the return circuit of 3YQJ in the voltage switching circuit. The device can realize the advantages of small amount of manual operation, high switching reliability and good safety of power grid operation.

Description

A voltage switching automatic parallel device

technical field

The invention relates to the technical field of electric power system relay protection equipment, in particular to an automatic parallel device for voltage switching.

Background technique

As an automatic device commonly used in comprehensive automatic substations, the voltage switching box plays the role of switching and paralleling the secondary voltage. For the electrical components connected to the substation with single-bus section wiring mode, when the two-section busbars are operated separately, in order to ensure that the primary system and the secondary system maintain corresponding voltages, avoid protection or automatic device malfunction or refusal to operate , The voltage secondary circuit of the protection and automatic device is required to switch synchronously with the change of the primary operation mode of the main wiring.

Whether the voltage switching circuit is good or not is directly related to whether the protection and automatic devices can operate correctly, and even affects the safe and stable operation of the power grid. Start the voltage switching intermediate relay 3YQJ with the normally open auxiliary contact of the isolation switch, and use its contacts to realize the automatic switching of the voltage circuit. The abnormality of the voltage switching circuit caused by the poor contact of the auxiliary node of the isolating switch or the improper conversion leads to abnormal parallel faults of the bus voltage, which brings great safety hazards to safe production.

The parallel circuit of the conventional voltage switching box can only be switched manually, that is, manually turn the parallel handle to the parallel position to force the connection of the two bus voltages. However, frequent operation of the switching handle may lead to poor contact of the nodes, and if the parallel time is too long, it will cause the circulation of the two voltage transformers. In extreme cases, the parallel circuit may not work normally, causing the voltage secondary circuit to be disconnected, blocking protection, and the meter will lose measurement, which will affect the safe and stable operation of the power grid.

During the process of realizing the present invention, the inventors found that the prior art at least has defects such as large amount of manual operations, low reliability of switching, and poor safety of power grid operation.

Contents of the invention

The object of the present invention is to solve the above problems and propose an automatic parallel device for voltage switching to achieve the advantages of less manual operation, high switching reliability and good grid operation safety.

In order to achieve the above object, the technical solution adopted by the present invention is: an automatic parallel device for voltage switching, including a voltage transformer 1YHA, a voltage transformer 1YHB and a voltage transformer connected to phase A, phase B and phase C of the three-phase AC power Transformer 1YHC, and low-voltage relay 1YJ, low-voltage relay 2YJ and low-voltage relay 3YJ connected in parallel to the voltage secondary circuits of voltage transformer 1YHA, voltage transformer 1YHB and voltage transformer 1YHC respectively;

The normally open node ①② of the low-voltage relay 1YJ, the normally open node ①② of the low-voltage relay 2YJ and the normally open node ①② of the low-voltage relay 3YJ are connected in series into the starting coil of the voltage parallel circuit 3YQJ after parallel connection;

Further, the above-mentioned voltage switching automatic parallel device also includes a switching intermediate voltage relay 1ZJ arranged between the voltage secondary winding and the secondary circuit of the voltage transformer 1YHA, voltage transformer 1YHB and voltage transformer 1YHC .

Further, the switching intermediate voltage relay 1ZJ specifically includes a static intermediate voltage relay whose model is JZ-7GY-441K.

The normally closed node ③④ of the low-voltage relay 1YJ, the normally closed node ③④ of the low-voltage relay 2YJ and the normally closed node ③④ of the low-voltage relay 3YJ are serially inserted into the starting coil of the intermediate relay 1ZJ in order to prevent the secondary voltage from flowing to the primary The device is reverse charging. The normally open auxiliary node (11)(12) of the intermediate relay 1ZJ is connected in series with the circuit breaker auxiliary node OF normally open (11)(14) and then connected to the return circuit of the parallel relay 3YQJ. The purpose of this design is that when the low-voltage relay operates, the voltages of sections I and II are automatically paralleled, and the intermediate relay 1ZJ is reset, and its normally open node is opened.

Further, the above-mentioned voltage switching automatic parallel device also includes a man-machine for setting the measurement range of the voltage to be measured, collecting and displaying the maximum and minimum values of the voltage to be measured, and setting the undervoltage reset mode interactive unit;

The human-computer interaction unit is respectively connected to the exciting coils of the low voltage relay 1YJ, low voltage relay 2YJ and low voltage relay 3YJ; the measurement range of the voltage to be measured is the low voltage relay 1YJ, low voltage relay 2YJ And the undervoltage setting range of the low voltage relay 3YJ.

Further, the human-computer interaction unit includes a panel, which is used to set the measurement range of the voltage to be measured and a button for setting the current reset mode as manual reset mode or automatic reset mode, and is used to automatically capture the maximum and minimum values of the voltage to be measured. The voltage sensor of the value is used to display the measurement range of the voltage to be measured, the maximum and minimum values of the voltage to be measured, the display screen of the current reset mode, and the manual reset button for manual reset;

The button is arranged on the panel, and the button and the voltage sensor are respectively connected to the display screen; the voltage sensor and the manual reset button are respectively connected to the excitation coils of the low voltage relay 1YJ, the low voltage relay 2YJ and the low voltage relay 3YJ .

Further, the above-mentioned voltage switching automatic parallel device also includes an AC air switch 1ZK with leakage protection connected in the voltage secondary circuit of the voltage transformer 1YHA, voltage transformer 1YHB and voltage transformer 1YHC;

The tripping alarm node SD of the air switch is connected with the voltage secondary air switch of the voltage transformer 1YHA, the voltage transformer 1YHB and the voltage transformer 1YHC and the voltage parallel relay 3YQJ.

Further, the tripping and alarming normally closed nodes (91) (92) of the air switch are connected in series to the start-up loop for voltage switching;

Further, the air switch includes C65N series circuit breakers.

Further, the low-voltage relay 1YJ, low-voltage relay 2YJ and low-voltage relay 3YJ all use JZ-7G series intermediate voltage relays;

The installation methods of the low voltage relay 1YJ, low voltage relay 2YJ and low voltage relay 3YJ are guide rail installation.

Further, the low-voltage relay 1YJ, low-voltage relay 2YJ and low-voltage relay 3YJ are all set by dial switches; the low-voltage relay 1YJ, low-voltage relay 2YJ and low-voltage relay 3YJ all have a housing containing terminals .

The voltage switching automatic parallel device of each embodiment of the present invention, owing to comprise the voltage transformer 1YHA, 1YHB and 1YHC that are respectively connected with A, B and C phase of three-phase alternating current power supply, and be respectively connected in parallel with voltage transformer 1YHA, 1YHB and The low voltage relays 1YJ, 2YJ and 3YJ of the voltage secondary circuit of 1YHC; the normally open nodes of the low voltage relays 1YJ, 2YJ and 3YJ, the normally open nodes of the low voltage relay 1YJ ①②, the normally open nodes of the low voltage relay 2YJ ①② and the normally open node ①② of the low-voltage relay 3YJ, which are sequentially connected in series to the starting coil of the voltage parallel circuit 3YQJ of the voltage transformer 1YHA, voltage transformer 1YHB and voltage transformer 1YHC;

The normally closed node ③④ of the low-voltage relay 1YJ, the normally closed node ③④ of the low-voltage relay 2YJ and the normally closed node ③④ of the low-voltage relay 3YJ are serially connected to the starting coil of the intermediate relay 1ZJ in series, and when its normally closed node ③④ is opened Afterwards, the intermediate relay is reset, and the nodes ②③, ④⑤, ⑧⑨ are disconnected to prevent secondary reverse charging to the primary. 14) Connect the return circuit of parallel relay 3YQJ after series connection. Automatically run separately after the voltage returns to normal.

Further, the C65N/H circuit breaker in the voltage switching automatic parallel device adopts the SD alarm node of the electrical auxiliary device, and the contact can be opened and closed when the circuit breaker is in normal operation, but its node will not follow when the fault trips. Closed to prevent secondary circuit misparalleling caused by air breaker tripping when the secondary voltage circuit is short-circuited or grounded

Further, the OF air switch auxiliary node of the C65N/H circuit breaker electrical auxiliary device in the voltage switching automatic parallel device; as the air switch is opened and closed, its state changes accordingly, so that after the air switch is disconnected, its normally open node (11), (14) are closed, start the voltage parallel circuit, and realize the automatic parallel of the voltage circuit.

This function allows the operator to directly pull the PT’s secondary circuit breaker without switching the parallel handle. At this time, the auxiliary node of the circuit breaker is closed to energize the parallel relay, omitting the step of operating the parallel handle, reducing the time for PT paralleling, and effectively Eliminate the loss of pressure caused by poor contact caused by improper switching handle operation; thus, it can overcome the defects of large amount of manual operation, low switching reliability and poor safety of power grid operation in the prior art, so as to achieve small amount of manual operation and high switching reliability And the advantages of good grid operation security.

Additional features and advantages of the invention will be set forth in the description which follows, and in part will be apparent from the description, or may be learned by practice of the invention.

The technical solutions of the present invention will be described in further detail below with reference to the accompanying drawings and embodiments.

Description of drawings

The accompanying drawings are used to provide a further understanding of the present invention, and constitute a part of the description, and are used together with the embodiments of the present invention to explain the present invention, and do not constitute a limitation to the present invention. In the attached picture:

Figure 1 is the wiring diagram of a conventional voltage circuit; in Figure 1, G1 and G2 are the auxiliary nodes of the PT isolation switch of sections 1 and 11 respectively; 1FG and 2FG are the isolation switches of bus tie 1 and 11 respectively, and DL is the auxiliary node of the bus tie switch;

Fig. 2 is the wiring diagram of adding low-voltage relays to the voltage secondary circuit of the voltage switching automatic parallel device of the present invention; in Fig. 2, 1YJ, 2YJ, 3YJ are low-voltage relays, 1ZK is an air switch, and ZJ is an intermediate relay node;

Fig. 3 is a schematic diagram of the working principle of the low-voltage relay normally closed node locking and resetting voltage relay in the voltage switching automatic parallel device of the present invention (that is, the secondary switching control circuit diagram of the voltage transformer); in Fig. 3, G1 and G2 are voltage mutual inductance Auxiliary node of isolator switch;

Figure 4a (top view), Figure 4b (front view), and Figure 4c (left/right view) are schematic diagrams of the external structure of the voltage relay in the voltage switching automatic parallel device of the present invention;

Fig. 5 is the SD alarm node wiring diagram of the C65N/H circuit breaker electrical auxiliary device in the voltage switching automatic parallel device of the present invention;

Fig. 6 is a wiring diagram of the OF state indicating node of the electric auxiliary device of the C65N/H circuit breaker in the voltage switching automatic parallel device of the present invention (that is, the schematic diagram of the auxiliary contact structure of the OF circuit breaker);

Fig. 7 is a schematic diagram of the parallel connection of the three-phase nodes of the voltage switching automatic parallel device IYJ (IIYJ) of the present invention [that is, a schematic diagram of the IYJ (IIYJ) synthetic contact structure];

Fig. 8 is a schematic diagram of the working principle of the voltage switching automatic paralleling device of the present invention (that is, the principle diagram of the voltage paralleling circuit after modification).

Detailed ways

The preferred embodiments of the present invention will be described below in conjunction with the accompanying drawings. It should be understood that the preferred embodiments described here are only used to illustrate and explain the present invention, and are not intended to limit the present invention.

According to the embodiment of the present invention, as shown in Fig. 1-Fig. 8, a voltage switching automatic parallel device is provided, including voltage transformer 1YHA, voltage transformer Voltage transformer 1YHB and voltage transformer 1YHC, and low-voltage relay 1YJ, low-voltage relay 2YJ and low-voltage relay 3YJ connected in parallel to voltage secondary circuits of voltage transformer 1YHA, voltage transformer 1YHB and voltage transformer 1YHC respectively; low-voltage relay The normally open node ①② of 1YJ, the normally open node ①② of low-voltage relay 2YJ and the normally open node ①② of low-voltage relay 3YJ are connected in series with the starting coil of voltage parallel relay of voltage transformer 1YHA, voltage transformer 1YHB and voltage transformer 1YHC in sequence The normally open auxiliary node (11) (12) of the intermediate relay 1ZJ is connected in series with the return circuit of the parallel relay 3YQJ after the normally open auxiliary node (11) (14) of the air-opening auxiliary node OF is connected in series. Automatically run separately after the voltage returns to normal.

Here, low-voltage relay 1YJ, low-voltage relay 2YJ and low-voltage relay 3YJ all use JZ-7G series voltage relays; the installation methods of low-voltage relay 1YJ, low-voltage relay 2YJ and low-voltage relay 3YJ are all rail-mounted. The low-voltage relay 1YJ, low-voltage relay 2YJ and low-voltage relay 3YJ are all set by dial switches; the low-voltage relay 1YJ, low-voltage relay 2YJ and low-voltage relay 3YJ all have shells with terminals.

The voltage switching automatic parallel device of the above embodiment also includes switching intermediate voltage relay 1ZJ arranged between voltage secondary winding and voltage secondary circuit of voltage transformer 1YHA, voltage transformer 1YHB and voltage transformer 1YHC; low voltage relay The normally closed node ③④ of 1YJ, the normally closed node ③④ of low voltage relay 2YJ and the normally closed node ③④ of low voltage relay 3YJ are connected in series to the coil circuit of switching intermediate voltage relay 1ZJ; the auxiliary nodes ②③, ④⑤, switching intermediate voltage relay 1ZJ, ⑧⑨, connected between the secondary winding of voltage transformer 1YHA, voltage transformer 1YHB and voltage transformer 1YHC and the voltage secondary circuit. Switching intermediate voltage relay 1ZJ, specifically including static intermediate voltage relay model JZ-7GY-441K.

The voltage switching automatic parallel device of the above embodiment also includes a human-computer interaction unit for setting the measurement range of the voltage to be measured, collecting and displaying the maximum and minimum values of the voltage to be measured, and setting the undervoltage reset mode; The human-computer interaction unit is respectively connected with the excitation coils of low voltage relay 1YJ, low voltage relay 2YJ and low voltage relay 3YJ; the measuring range of the voltage to be measured is the undervoltage setting of low voltage relay 1YJ, low voltage relay 2YJ and low voltage relay 3YJ scope.

Here, the human-computer interaction unit includes a panel, which is used to set the measurement range of the voltage to be measured and the button for setting the current reset mode as manual reset mode or automatic reset mode, and is used to automatically capture the maximum and minimum voltage values of the voltage to be measured. The sensor is used to display the measurement range of the voltage to be measured, the maximum and minimum values of the voltage to be measured, and the display screen of the current reset mode, as well as the manual reset button for manual reset; the button is set on the panel, and the button and the voltage sensor They are respectively connected to the display screen; the voltage sensor and the manual reset button are respectively connected to the exciting coils of the low voltage relay 1YJ, the low voltage relay 2YJ and the low voltage relay 3YJ.

The voltage switching automatic parallel device of the foregoing embodiment includes an AC air switch with leakage protection connected to the voltage secondary circuit of the voltage transformer 1YHA, the voltage transformer 1YHB and the voltage transformer 1YHC; the tripping alarm node of the air switch, and The voltage secondary air switch of voltage transformer 1YHA, voltage transformer 1YHB and voltage transformer 1YHC is connected with the parallel voltage relay. The tripping alarm normally closed node (91) (92) of the air switch is connected in series with the starting circuit of the voltage parallel relay 3YQJ. The node will not change position during normal operation, but can reliably operate after the circuit short circuit trips, disconnect its normally closed node (91) (92), and cut off the voltage parallel circuit to prevent the secondary voltage from being wrongly paralleled. The air switch includes C65N series circuit breakers.

Compared with the prior art, the implementation process of the voltage switching automatic parallel device in the above embodiment mainly includes the following aspects:

⑴Application of low voltage relay

Conventional voltage loop wiring is: potential transformer (potential transformer, referred to as PT) main body wiring leads to the terminal box to form a loop, and then switches through the auxiliary node of the PT knife switch, and after switching, passes through the secondary circuit breaker of the PT (the circuit breaker is the air switch) , sent to the main control room. When a group of PTs need to be overhauled, the operator should first manually switch the parallel handle to the parallel position, then open the PT secondary circuit breaker, and finally open the PT knife switch. The voltage loops have been paralleled after the parallel handles are switched.

After using the circuit modified by the applicant, the operator does not need to switch the parallel handle, and directly pulls the PT secondary air switch. At this time, the air switch 1ZK auxiliary node OF normally closed node (11) (12) is closed, so that the parallel relay is excited. In this way, the step of operating the parallel handle is omitted, which reduces the time for PT paralleling. More importantly, it effectively prevents the pressure loss caused by improper operation of the switching handle and poor contact. When putting the PT into operation, the PT knife switch should be closed first, and then the secondary circuit breaker 1ZK should be closed to complete the operation, which simplifies the operation steps and ensures the maximum reliability.

Figure 1 is the wiring diagram of the voltage loop before improvement (that is, the wiring diagram of the conventional voltage loop). As shown in Figure 1: During normal operation, the switch handle 7QK is in the disconnected position. When the secondary voltages of sections I and II are required to be paralleled, it is necessary to manually close the ①② node of the handle 7QK to connect the parallel circuit; it is also necessary to manually Close the ③④ nodes of the handle 7QK to connect the return circuit.

⑵The application of adding low-voltage relay to the circuit

Figure 2 is a schematic diagram of installing a low-voltage relay in the voltage secondary circuit. Connect the low voltage relays 1YJ, 2YJ, 3YJ in parallel to the voltage secondary circuit of the PT. When the voltage of the voltage circuit is too low, for example, when the primary insurance of the PT is disconnected, the low voltage relays 1YJ, 2YJ, 3YJ act, and the normally open nodes ①② are connected in parallel The starting coil of the relay 3YQJ makes the coil excited, and the voltages of sections I and II run in parallel; the normally open auxiliary nodes (11)(12) of the intermediate relay 1ZJ are connected in series with the auxiliary node OF normally open nodes (11)(14) of the air switch Enter the return circuit of parallel relay 3YQJ. When the voltage is normal, the normally open auxiliary nodes (11) (12) are closed to start the return circuit of the parallel relays, the 3YQJ nodes are opened, and the voltage circuits operate separately.

Voltage relays are divided into active voltage relays and passive voltage relays. The low-voltage relay used this time is an active voltage relay, which is used in the relay protection devices of generators, transformers and transmission lines as the starting element for undervoltage lockout. The main features are as follows:

①The main circuit is composed of an integrated circuit, which has extremely high accuracy and return coefficient, and has fast action speed, low power consumption, and wide setting range. When used as an undervoltage relay, there is no phenomenon of vibration, contact adhesion, and off-axis;

②The dial switch is used for setting, which is intuitive and convenient;

③ High anti-interference ability and reliability;

④The shell of the voltage relay, including terminal wiring, completely replaces all voltage relay series on the market, which is convenient and intuitive.

The main features of passive voltage relays are as follows:

① No need for DC auxiliary power supply, which completely solves the interference and heat generation problems from DC power supply, and greatly improves the reliability of work;

②The main circuit is composed of a thick film circuit: it has extremely high accuracy, return coefficient, fast action speed, low power consumption, and wide setting range. When used as a low-voltage relay, there is no vibration, contact adhesion, and off-axis phenomenon;

③The voltage relay adopts the dial switch for setting, which is intuitive and convenient;

④ High anti-interference ability and reliability.

In the voltage switching automatic parallel device of the above embodiment, the selected voltage relay should have the following characteristics:

①Return time: Use the method of cutting off the circuit to cut off the power of the voltage relay, and the return time of the voltage relay is not greater than 30mS; except for the power-off delay time voltage relay;

②The allowable variation range of power supply voltage: the voltage variation is 0.8 to 1.1 times of the rated voltage;

③Contact capacity: the voltage relay output contact can be disconnected no more than 250V, the DC inductive load circuit with a time constant of 5±0.75ms is 50W; the AC circuit with a voltage no more than 250V is 50VA, and the voltage relay can be connected to 5A for a long time current;

④ Power consumption: No more than 5W at rated voltage; ⑤ Ambient temperature: -10℃~+50℃; 2000V RMS AC voltage, no insulation breakdown or arcing phenomenon after 1 minute test;

⑦Insulation resistance: The conductive terminals of the voltage relay are connected together between the exposed non-metallic part and the shell, and the insulation resistance measured by a megohmmeter with an open circuit voltage of 500V is not greater than 300MΩ; In the circuit load of the capacity, the electrical life is 100,000 times; ⑨Anti-interference performance: Voltage relay interference complies with DL478-92 "General Technical Conditions for Static Voltage Relay Protection and Safety Automatic Devices". the

In the voltage switching automatic parallel device of the above embodiment, the working principle of the voltage relay includes: the output type of undervoltage and voltage loss is the same voltage relay, when the detected voltage is greater than the undervoltage set value, the output voltage relay operates; when the detected voltage is low When the undervoltage setting value or voltage loss occurs, and the duration exceeds the undervoltage delay setting time, the output voltage relay is released; the undervoltage setting range is the measurement range, which is set by the panel buttons; automatically captures the maximum value of the measured voltage and The minimum value is displayed; there are two options for undervoltage reset, automatic and manual. In the voltage switching automatic parallel device, the installation method of the voltage relay is guide rail installation.

(3) The application of adding intermediate voltage relays to the circuit

Fig. 3 is a schematic diagram of a normally closed node blocking reset voltage relay of a low voltage relay. The normally closed nodes of the low-voltage relays 1YJ, 2YJ and 3YJ are connected in series to the coil circuit of the switching intermediate voltage relay ZJ, and the auxiliary nodes ②③, ④⑤, ⑧⑨ of the switching intermediate voltage relay 1ZJ are disconnected to realize the primary and secondary isolation of the voltage circuit.

The model used for the static intermediate voltage relay can be JZ-7GY-441K (Shanghai Linhao Electric Co., Ltd.), and the working voltage is 220V DC. The technical characteristics of the static intermediate voltage relay are as follows:

①A new installation method, which can be installed on rails or fixed, with beautiful installation, small size, and convenient and intuitive wiring;

②Using high-performance sealed voltage relay, moisture-proof, dust-proof, continuous line, high reliability;

③ Accurate operating voltage, high return coefficient, no jitter, low power consumption, multiple nodes operate or return at the same time (100% controllability);

④ After the voltage relay operates, there are light indications and power indications;

⑤ Long electrical life and mechanical life of the voltage relay;

⑥ High level of insulation withstand voltage, large contact capacity, and small contact resistance;

⑦ Good anti-interference characteristics, suitable for places with strong interference or poor quality of power supply voltage;

⑧No need to consider the design of the contact form like the old model, the new multi-contact form is convenient for model selection.

Intermediate voltage relays are divided into quick-action conventional voltage relays, power-on delay type intermediate electrical voltage relays, power-off delay intermediate voltage relays, etc. JZ-7G series intermediate voltage relays are used in various protection and automatic control devices to increase the contact capacity of protection and control circuits. This series of intermediate voltage relays uses a static electronic control circuit to control the simultaneous conduction or disconnection of multiple sealed inlets. JZS-7G series rail-mounted intermediate voltage relays (that is, rail-type intermediate voltage relays) are used in various protection and automatic control devices to increase the contact capacity of protection and control circuits. This series of intermediate voltage relays adopts a static electronic control circuit to control the simultaneous conduction or disconnection of multiple sealed inlets. It has the following performance and characteristics:

① The time of power-on delay or power-off delay can be freely adjusted according to needs;

②The energy storage delay type intermediate voltage relay, the capacitor stores energy at the moment of power on, and the voltage relay controls the disconnection or action of the intermediate voltage relay through the digital circuit according to the user's settings, so as to achieve the purpose of delay.

The main parameters of JZS-7G series intermediate voltage relays are as follows:

① Return time: In the method of cutting off the circuit, the voltage relay is powered off, and the return time of the voltage relay is not greater than 30mS; except for the power-off delay time voltage relay; , can also be wide power supply circuit; ③Contact capacity: the voltage relay output contact can be disconnected no more than 250V, the time constant of 5±0.75mS is 50W for DC inductive load circuit; the voltage is no more than 250V for AC circuit is 50VA, The voltage relay can be connected to 5A current for a long time; ④ Power consumption: no more than 5W under rated voltage; ⑤ Ambient temperature: -10℃~+50℃; Between metal parts or shells, it can withstand 2000V effective value) AC voltage, and there is no insulation breakdown or arcing phenomenon after 1 minute test;

⑦Insulation resistance: The conductive terminals of the voltage relay are connected together between the exposed non-metallic part and the shell, and the insulation resistance measured by a megohmmeter with an open circuit voltage of 500V is not greater than 300MΩ; In the circuit load of the capacity, the electrical life is 100,000 times; ⑨Anti-interference performance: Voltage relay interference complies with DL478-92 "General Technical Conditions for Static Voltage Relay Protection and Safety Automatic Devices".

⑷ Discussion and application of adding air switch and its auxiliary nodes and alarm nodes to the circuit

When a short-circuit fault occurs in the voltage secondary circuit, the secondary circuit breaker trips, and the auxiliary node is closed to connect the parallel circuit, causing false tripping of the normal circuit. In order to avoid this phenomenon, the applicant adopts an AC circuit breaker with leakage protection. When a certain section of the voltage circuit trips due to a short circuit, the circuit breaker will automatically trip and disconnect the faulty circuit, because the parallel voltage is connected in series to the normally closed node of the alarm. The starting circuit of the relay is normally closed and opened in case of failure, and the parallel starting circuit is cut off, and the voltage secondary circuit is forbidden to be paralleled by mistake.

The models used for the air switch and its auxiliary nodes: Schneider C65N series circuit breakers were selected and used after investigation and comparison. C65 series products have the following characteristics:

①On the basis of excellent and mature products from France, the special requirements of China's low-voltage power distribution are considered. Since the C65 series is based on the reference to the mature product C60 series in foreign markets, it fully meets the supplementary requirements for switch safety in the Chinese low-voltage market. Regulations, so it meets the requirements of GB10963-1999 and GB16917 while complying with the IEC898 standard. Because of this, it was awarded the CCE security certificate.

② More and more comprehensive selection range and stronger performance, meeting the requirements of different fields for power distribution. The main technical parameters of C65 series products, such as breaking capacity, impact voltage resistance, overvoltage protection, and fast closing, are significantly improved compared with C45; At the same time, the product variety has also been increased to meet the needs of different users.

③Provide richer and more convenient installation accessories and accessories to truly meet the needs of automation control. While people's safety requirements for electrical products are getting higher and higher, everyone also hopes for easier installation. C65 series circuit breakers are safe and simple to install accessories and Vigi leakage protection accessories, and can be installed directly without any tools. At the same time, these rich accessories, such as OF auxiliary node, SD alarm node, MX+OF shunt trip unit, MN undervoltage trip unit, and CT contactor, TL voltage relay, IH timing switch, IHP programmable timing switch , which can meet the requirements of automatic control system.

④Super performance: The breaking capacity is significantly improved compared with C45 miniature circuit breaker, and the breaking capacity of all rated current values is the same; among them: C65N is 6 000A (IEC898) C65H is 10000A (IEC898) with C/D type protection characteristics , the rated current range is more complete, and the rated current range of C/D type is 1~63A;

⑤ Isolation function: Comply with the supplementary safety requirements of the circuit breaker with isolation function in the GB14048.2 standard, which is different from the C45 miniature circuit breaker:

a. The impact withstand voltage can be increased to 6kV;

b. There are green stripes on the handle to show that the contact is indeed in the disconnected position;

c. Super fast closing and breaking of contacts.

⑥VigiC65 leakage protection accessories: The leakage accessories have two rated current levels: 32A/63A; the instantaneous tripping value for personal electric shock protection is 30mA. Leakage protection accessories have two kinds of electromagnetic releases and electronic releases. They have filtering devices, which can effectively prevent malfunctions caused by instantaneous voltage changes and surge currents. The electronic releases must have a safe working voltage of 50V, 1P+N, 2P Electronic leakage accessories also have:

⑦280V overvoltage protection to meet market demand

a. Automatic control function:

A variety of electrical accessories, such as OF auxiliary nodes, SD alarm nodes, MX+OF shunt trip units, MN undervoltage trip units, and multi9 series control electrical components, such as CT contactors, TL voltage relays, etc. With the cooperation of the controller, the automatic control of the low-voltage power distribution system is realized.

b. Easy to install:

It has greater advantages than C45 in terms of convenient installation and wiring: the combination of circuit breaker (MCB) and leakage protection accessories (VigiC65) is more perfect and safer. It adopts international standard DIN (double card position U-shaped) symmetrical track installation, and the circuit breaker terminal can be connected with comb-shaped terminal blocks and wires, and the maximum cross-section of the wires can reach 35mm2.

c. To ensure safer operation and use: the multi-pole circuit breaker is equipped with pole-interval grids to ensure safe wiring; the handle can be equipped with a lock to prevent misoperation; the protection level can be improved by adding a rotating handle.

C65N circuit breaker has the following functions: short circuit protection, overload protection, control, C65N circuit breaker can be used for terminal power distribution and industrial equipment. The technical parameters of C65N circuit breaker are as follows:

①Electrical parameters

Rated voltage: 440V AC;

Breaking capacity (IEC898), see the table below:

Current limit level: 3;

Quick closing: ensure the reliable operation of the impact load and prolong the electrical life of the circuit breaker;

Mechanical life (O-C): 20000 times;

②Environment

Moisture and heat resistance: Class 2 (at a temperature of 55°C, a relative humidity of 95%);

Reference weight (grams), see small table:

Wiring: terminal wiring area:

25A and below can be connected with 16mm2 multi-strand flexible wire, or 25mm2 single-strand hard wire;

32A to 63A can be connected with 25mm2 multi-strand flexible wire, or 35mm2 single-strand hard wire;

③C-shaped curve:

Protection of general load and distribution cables;

Electrical parameters of C-shaped curve:

Rated current: 1~63A (at 30°C);

Tripping characteristics: instantaneous tripping 5~10In;

④D-shaped curve:

Protection of impact loads with large starting currents (motors, transformers);

Electrical parameters of the D-shaped curve:

Rated current: 1~63A (at 30°C);

Tripping characteristics: instantaneous tripping 10~14In;

⑤Quality approval:

Conform to IEC 898/ GB 10963-1999;

Obtained CCEE security certification.

The selected C65 circuit breaker has a rated current of 40A and a product model of C-type 17878. Vigi C65 leakage protection accessories 30mA instantaneous type, AC type ELM/ELE electromagnetic/electronic type. Vigi C65 leakage protection accessories, assembled with 1-pole, 2-pole, 3-pole and 4-pole C65N/H type circuit breakers can provide:

① indirect contact protection;

②Supplementary protection for direct contact (30mA);

③ Electrical equipment insulation fault protection;

④Momentary type;

⑤ Ensure instantaneous tripping (no time delay);

⑥AC type, used for AC sine wave. Combination of leakage protection accessories and circuit breakers: C65 circuit breaker + Vigi leakage protection accessories = leakage circuit breaker.

The relevant instructions of Vigi C65 ELM electromagnetic leakage protection accessories are as follows:

①Electromagnetic leakage protection accessories do not require any auxiliary power supply for operation. The VigiC65 accessories are internally composed of residual current voltage relays and zero-sequence current transformers;

②Technical data

Prevent malfunction caused by transient overvoltage (lightning, grid operation, etc.);

Tripping indication: There is a red leakage tripping indication on the Vigi accessory operating handle;

Rated leakage operating current: 30 mA;

Rated voltage: 230/400V AC, 50HZ;

Rated current: In=32A, In=63A;

Manual control: The handle allows two reset modes: the circuit breaker and the leakage device are reset at the same time The circuit breaker and the leakage device are reset separately, the leakage accessory is reset first, and the circuit breaker is reset later. Weight (grams), see table below:

③Wiring

In=32A leakage accessories can be connected to 16mm ² multi-strand flexible wire or 25mm ² single-strand hard wire;

In=63A leakage accessories can be connected to 25mm ² multi-strand flexible wire or 35mm ² single-strand hard wire;

④Standard: Comply with IEC1009-1/GB 16917 standard and obtain CCEE safety certification;

⑤ Note: Vigi leakage accessories with In=32A have special devices, which can prevent it from being assembled with C65 circuit breakers with rated currents greater than 32A.

For the electrical auxiliary device of C65N/H circuit breaker, see Figure 5 (SD alarm node) and Figure 6 (OF status indication node). When the SD alarm node circuit breaker fails to trip, it sends out a signal. There is a mechanical indication on the front panel, which can indicate the failure to trip. The OF auxiliary node indicates the closing and opening status of the circuit breaker. The technical data of the electrical auxiliary device of C65N/H circuit breaker are as follows:

① Comply with the standard: IEC 947-2;

②Auxiliary contact rated current, see the table below:

Wiring screw terminal, which can be connected with 1 or 2 wires with a maximum cross-section of ^2.5mm2 , and there is a clear mark next to the terminal.

The functions that can be realized by the voltage switching automatic parallel device of the above embodiment include:

⑴The effect achieved:

① Use the normally closed node of the PT knife switch to form a parallel circuit. When the PT for maintenance is out of operation and the knife switch is opened, the parallel circuit is started;

②Use the PT secondary circuit breaker auxiliary node, pull the PT secondary circuit breaker, and start the parallel circuit;

③ Use the normally open node of the low voltage relay to start the parallel circuit;

④ Parallel operation is not allowed after the secondary air switch trips due to failure;

⑵Economic benefits after transformation:

After the transformation, the failure rate of the voltage circuit has been reduced from 40% to less than 5%. Fully achieved the desired effect. In the past six months of implementation, a total of about 180,000 kW h of power loss due to PT disconnection has been reduced. Calculated based on the company's comprehensive electricity price of 0.500 yuan, it can save about 90,000 yuan in maintenance costs for deficiencies.

Compared with conventional switching circuits, the voltage switching automatic parallel device of the above embodiment can at least achieve the following beneficial effects:

(1) Use the normally open node of the low voltage relay to start the parallel circuit.

Conventional switching circuits are only performed manually or remotely under artificial circumstances, so it is not known whether the switched voltage is normal. After the circuit modified by the applicant, when the secondary voltage of the operating voltage transformer is lower than a certain value, it will automatically switch to the normal voltage circuit to run; Restore the switching circuit and still use the secondary voltage of the original transformer.

⑵ Parallel operation is not allowed after the secondary air switch trips due to failure.

In the conventional switching circuit, the secondary air switch trips, which proves that its next-level circuit is faulty, such as short circuit, grounding, etc. If switching blindly, it will inevitably cause both voltage transformers to lose power in the secondary stage. It has the effect of switching, and also switches the normal voltage secondary circuit to the faulty circuit. Through the circuit transformed by the applicant, this phenomenon will not occur by using the air switch trip alarm node control, and it can fully meet the operation requirements.

Finally, it should be noted that: the above is only a preferred embodiment of the present invention, and is not intended to limit the present invention. Although the present invention has been described in detail with reference to the foregoing embodiments, for those skilled in the art, it still The technical solutions recorded in the foregoing embodiments may be modified, or some technical features thereof may be equivalently replaced. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principles of the present invention shall be included within the protection scope of the present invention.

Claims (9)

1. A voltage switching automatic parallel device, characterized in that, comprises a voltage transformer 1YHA, a voltage transformer 1YHB and a voltage transformer 1YHC connected to the A phase, the B phase and the C phase of the three-phase AC power supply respectively, and parallel Low-voltage relay 1YJ, low-voltage relay 2YJ and low-voltage relay 3YJ connected to the voltage secondary circuit of voltage transformer 1YHA, voltage transformer 1YHB and voltage transformer 1YHC; The normally open node ①② of the low voltage relay 1YJ, the normally open node ①② of the low voltage relay 2YJ and the normally open node ①② of the low voltage relay 3YJ are connected in series to the voltage transformer 1YHA, voltage transformer 1YHB and voltage transformer in parallel The voltage of 1YHC is paralleled with the starting coil of relay 3YQJ; The intermediate relay 1ZJ normally open auxiliary node (11)(12) is connected in series with the air switch 1ZK normally open auxiliary node (11)(14) and then connected in parallel with the auxiliary node of the manual control handle ③④, the bus tie switch and its isolating knife switch. The return coil of the parallel relay 3YQJ connected in series to the voltage switching circuit. 2. The voltage switching automatic parallel device according to claim 1, characterized in that it also includes a voltage secondary winding and a voltage secondary circuit arranged between the voltage transformer 1YHA, the voltage transformer 1YHB and the voltage transformer 1YHC. Intermediate voltage relay 1ZJ for switching between; The normally closed nodes ③④ of the low-voltage relays 1YJ, 2YJ, and 3YJ are sequentially connected in series to the coil loop of the switching intermediate voltage relay 1ZJ; the auxiliary nodes ②③, ④⑤, ⑧⑨ of the switching intermediate voltage relay 1ZJ are connected to the voltage transformer 1YHA 1. Between the voltage secondary windings of voltage transformer 1YHB and voltage transformer 1YHC and the secondary circuit to achieve primary and secondary isolation and prevent reverse charging of the voltage circuit. 3. The voltage switching automatic parallel device according to claim 2, wherein the switching intermediate voltage relay 1ZJ specifically includes a static intermediate voltage relay whose model is JZ-7GY-441K. 4. The voltage switching automatic parallel device according to claim 1 or 2, characterized in that it also includes a measurement range for setting the voltage to be measured, collecting and displaying the maximum and minimum values of the voltage to be measured, and setting Human-computer interaction unit with fixed undervoltage reset mode; The human-computer interaction unit is respectively connected to the exciting coils of the low voltage relay 1YJ, low voltage relay 2YJ and low voltage relay 3YJ; the measurement range of the voltage to be measured is the low voltage relay 1YJ, low voltage relay 2YJ And the undervoltage setting range of the low voltage relay 3YJ. 5. The voltage switching automatic parallel device according to claim 4, wherein the human-computer interaction unit includes a panel for setting the measurement range of the voltage to be measured and the current reset mode as manual reset or automatic reset mode button, a voltage sensor for automatically capturing the maximum and minimum values of the voltage to be measured, a display screen for displaying the measurement range of the voltage to be measured, the maximum and minimum values of the voltage to be measured, and the current reset mode, and Manual reset button for manual reset; The button is arranged on the panel, and the button and the voltage sensor are respectively connected to the display screen; the voltage sensor and the manual reset button are respectively connected to the excitation coils of the low voltage relay 1YJ, the low voltage relay 2YJ and the low voltage relay 3YJ . 6. The voltage switching automatic parallel device according to claim 1 or 2, characterized in that, it also includes a leakage circuit connected to the voltage secondary circuit of the voltage transformer 1YHA, voltage transformer 1YHB and voltage transformer 1YHC. Protected AC air switch 1ZK; The SD trip alarm normally closed nodes (91), (92) of the air switch 1ZK are connected with the voltage secondary air switch of the voltage transformer 1YHA, the voltage transformer 1YHB and the voltage transformer 1YHC and the starting coil of the parallel voltage relay 3YQJ , the node does not change position when the circuit breaker is in normal operation, but its normally closed nodes (91), (92) are opened when the circuit is short-circuited and tripped, and the voltage parallel circuit is cut off to prevent the voltage parallel circuit from malfunctioning when the circuit fault trips. The two sections of busbars are all de-energized; The normally closed node (11)(12) of the air-opening auxiliary node OF is connected in series with the starting coil of the parallel relay 3YQJ, the normally open node (11)(14) of the air-opening auxiliary node OF is connected with the normally open node (11) of the intermediate relay 1ZJ (12) Connect the return coil of the parallel relay 3YQJ after being connected in series. 7. The voltage switching automatic paralleling device according to claim 6, wherein the air switch includes a C65N series circuit breaker. 8. The voltage switching automatic parallel device according to claim 1, characterized in that, the low-voltage relay 1YJ, low-voltage relay 2YJ and low-voltage relay 3YJ all use JZ-7G series intermediate voltage relays; The installation methods of the low voltage relay 1YJ, low voltage relay 2YJ and low voltage relay 3YJ are guide rail installation. 9. The voltage switching automatic parallel device according to claim 1, characterized in that, the low voltage relay 1YJ, the low voltage relay 2YJ and the low voltage relay 3YJ are all set by dial switches; the low voltage relay 1YJ, The low-voltage relay 2YJ and the low-voltage relay 3YJ both have housings containing terminals.

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