CN102842951B - Low voltage loop-closing selective-tripping system - Google Patents

Abstract

The invention provides a low voltage loop-closing selective-tripping system, comprising auxiliary connection points of three air switches, a relay and a selective-tripping switch, wherein the relay comprises three normally open contacts; the selective-tripping switch comprises three groups of connection points, and moreover, only one group of connection points is located in the on-state; the auxiliary connection points of the three air switches are connected in series in order; the auxiliary connection point of the first air switch is connected with a live wire of a power supply source; the auxiliary connection point of the third air switch is connected in series with the first end of a coil of the relay; the second end of the coil of the relay is connected with a neutral wire of the power supply source; the three normally open contacts of the relay are connected with three input connection points in the three groups of connection points of the selective-tripping switch respectively; and three output connection points in the three groups of connection points of the selective-tripping switch are connected with opening coils of three opening loops of the three air switches respectively. With the adoption of the low voltage loop-closing selective-tripping system, the problem of voltage flicker of momentary interruption during the switching operation can be solved; the power can be supplied reliably; and the personal safety of operators can be guaranteed.

Description

Low-voltage ring closing and jumping system

technical field

The invention relates to the technical field of power supply, in particular to a low-voltage ring closing and jumping system.

Background technique

At present, there are many high-voltage users with dual power supplies and multiple power supplies, and these users have high requirements on the reliability and quality of power supply. Fig. 1 shows the main wiring diagram of the dual power supply system in the form of segmented wiring of medium and low voltage single bus bars in the prior art, which includes the first air switch QF1, the second air switch QF2 and the third air switch QF3, among which The first air switch QF1 and the second air switch QF2 are incoming line switches respectively, and the third air switch QF3 is a bus tie switch. During the switching operation of the dual power supply system, the voltage flicker of the user's busbar voltage will occur instantaneous power failure. The voltage flicker of instantaneous power failure has a great impact on modern electrical equipment. All electrical equipment equipped with computer chips will stop working. After these electrical equipment stop working, it will have very serious consequences for users. Many high-power gas discharge lighting lamps stop working after a few milliseconds of instantaneous power failure, and it takes several minutes to restart after the power is turned on again. This poses a great challenge to lighting power in important places. Some refrigeration equipment is also sensitive to voltage flicker caused by instantaneous power failure. It is sensitive and can be damaged even after a momentary power failure.

In order to prevent the impact of instantaneous power failure voltage flicker on users, the general measure is to connect the high-voltage side of many high-voltage users for a short time, and then disconnect the equipment that needs to be powered off from the power supply when the low-voltage side is connected for a short time To avoid voltage flicker due to instantaneous power failure during switching.

According to the above method of the prior art, due to the large voltage difference between the high-voltage side and the low-voltage side, the circulating current will exceed the protection setting value, causing the protection on the power supply side to operate, and an unexpected power outage will occur for users. At the same time, the large circulating current It will cause the circuit of the dual power supply system to be overloaded for a short time. This switching operation will cause the equipment to be burned due to the operator's misoperation, and increase the difficulty of scheduling, increasing the probability of electric shock accidents for the staff, and This method will also lengthen the time for the original single power supply system to become a dual power supply system, resulting in failure of some protection devices or changes in sensitivity.

In the prior art, short-term contact between the high-voltage side and the low-voltage side is used to avoid voltage flicker due to instantaneous power failure during the switching operation, resulting in unreliable power supply and personal safety of operators. For these problems, there is currently no Come up with effective solutions.

Contents of the invention

The main purpose of the present invention is to provide a low-voltage ring closing and tripping system to solve the problem of voltage flicker caused by instantaneous power failure during the switching operation through the short-term contact between the high-voltage side and the low-voltage side in the prior art, resulting in unreliable Power supply and the personal safety of operators cannot be guaranteed.

In order to achieve the above purpose, the present invention provides a low-voltage loop closing and switching system, which is used to control the switching of three air switches after closing the loop in the dual power supply system in the form of single bus segment wiring.

The low-voltage ring closing and tripping system of the present invention includes: auxiliary contacts of three air switches; a relay, including three normally open contacts; a tripping switch, including three groups of contacts and only one group of contacts is in the on state at a time;

Among the three air switches, the auxiliary contacts of the first air switch, the second air switch and the third air switch are sequentially connected in series, wherein the auxiliary contact of the first air switch is connected with the low-voltage loop closing and jumping system. The live wire of the power supply is connected, the auxiliary contact of the third air switch is connected in series with the first end of the coil of the relay, and the second end of the coil of the relay is connected with the neutral wire of the power supply;

The three normally open contacts of the relay are respectively connected to the three input contacts of the three sets of contacts of the selector switch, and the three output contacts of the three sets of contacts of the selector switch are connected to the three sets of contacts respectively. The opening coils of the three opening circuits of the air switch are connected.

Further, a fuse is also provided between the auxiliary contact of the first air switch and the live wire of the power supply.

Further, the relay also includes a fourth normally open contact, which is connected to the working indicator light and used for sending a ring closing signal.

Further, the relay is an AC intermediate relay.

Further, the rated voltage of the AC intermediate relay is AC (alternating current) 220V.

Further, the AC intermediate relay is a multi-contact AC intermediate relay with an electromagnetic solenoid structure.

Further, the three air switches are all universal air switches.

According to the technical solution of the present invention, the low-voltage loop closing and tripping system of the present invention adopts the switching operation mode of one of the three switches to be tripped after the low-voltage loop closing is started and automatically tripped after the loop is closed, which not only avoids the instantaneous The occurrence of voltage flicker due to power failure also ensures the reliability of power supply and the personal safety of operators.

Description of drawings

The accompanying drawings in the description are used to provide a further understanding of the present invention and constitute a part of the present application. The schematic embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute improper limitations to the present invention. In the attached picture:

Fig. 1 is the main wiring diagram of the dual power supply system of the low voltage single bus section wiring form in the prior art;

Fig. 2 is the schematic diagram of the ring-closing startup loop of the low-voltage ring-closing and jump-selecting system according to an embodiment of the present invention; and

Fig. 3 is a schematic diagram of a jump selection execution circuit of a low-voltage loop closing and jump selection system according to an embodiment of the present invention.

Detailed ways

It should be noted that, in the case of no conflict, the embodiments in the present application and the features in the embodiments can be combined with each other. The present invention will be described in detail below with reference to the accompanying drawings and examples.

In this embodiment, the low-voltage ring closing and jumping system of the present invention is used for the first air switch QF1, the second air switch QF2 and the Three air switches QF3 are selected for jump control after closing the ring.

In this embodiment, the low-voltage loop closing and jumping selection system of the present invention includes: a loop closing start circuit and a jump selection execution circuit.

Fig. 2 is a schematic diagram of a loop-closing startup circuit of a low-voltage loop-closing and jump-selecting system according to an embodiment of the present invention.

As shown in Figure 2, the loop closing start circuit includes:

The auxiliary contact 21 of the first air switch QF1, the auxiliary contact 22 of the second air switch QF2, and the auxiliary contact 23 of the third air switch QF3 are sequentially connected in series.

One end of the relay coil 24 is connected in series with the auxiliary contact 23 of the third air switch QF3, and the other end is connected with the neutral line N of the power supply.

One end of the fuse 25 is connected in series with the auxiliary contact 21 of the first air switch QF1, and the other end is connected with the live wire L of the low-voltage ring closing and jumping system of the present invention.

In this embodiment, only when the three air switches are all in the closing position, the auxiliary contacts of the three air switches are closed at the same time, the loop closing start circuit of the low-voltage loop closing and jumping system of the embodiment of the present invention shown in Figure 2 only connected.

Fig. 3 is a schematic diagram of a jump selection execution circuit of a low-voltage loop closing and jump selection system according to an embodiment of the present invention.

As shown in Fig. 3, the jump selection execution circuit mainly includes four normally open contacts of the relay and three sets of contacts of the jump selection switch.

Among them, the first normally open contact 31 of the relay is connected in series with the input contact A of the first group of contacts 35 of the selector switch, and the output contact a of the first group of contacts 35 is connected to the opening circuit of the first air switch QF1 The opening coil connection.

Among them, the second normally open contact 32 of the relay is connected in series with the input contact B of the second group of contacts 36 of the selector switch, and the output contact b of the second group of contacts 36 is connected to the opening circuit of the second air switch QF2 The opening coil connection.

Among them, the third normally open contact 33 of the relay is connected in series with the input contact C of the third group of contacts 37 of the selector switch, and the output contact c of the third group of contacts 37 is connected to the opening circuit of the third air switch QF3 The opening coil connection.

Wherein, the fourth normally open contact 34 of the relay, as a spare normally open contact, can be connected with the working indicator light for sending the ring closing signal.

In this embodiment, the relay is a multi-contact AC intermediate relay with an electromagnetic solenoid structure, its rated voltage is AC220V, the action time under the rated voltage is not more than 50 milliseconds, and the action time range of the measured opening and closing circuit is 31 ~33 ms.

In this embodiment, the first air switch QF1, the second air switch QF2 and the third air switch QF3 can all be universal low-pressure air switches of MT series and E series, and the voltage levels are all 220V. The measured opening time range of the air switch is 50-51 milliseconds.

In this embodiment, the jumper switch is a universal transfer switch, and among its three sets of contacts, only one set of contacts is in the on state at a time.

In this embodiment, during the normal operation of the dual power supply system shown in Figure 1, the first air switch QF1 and the second air switch QF2 are in the closing position, and the third air switch QF3 is in the opening position . After the system is closed, the low-voltage closed loop selection system of the present invention can select the first air switch QF1 or the second air switch QF2. According to the needs of the dual-power supply system, the low-voltage ring closing and jumping system of the present invention can have a variety of jumping combinations, as shown in the following table 1:

Table 1: Combination mode of jump selection for low voltage ring closing and jump selection system

In the above table 1, there are six kinds of jump selection combinations, which are explained as follows:

The first combination mode of jump selection: In the initial state, the first air switch QF1 and the second air switch QF2 are in the closing position, and the third air switch QF3 is in the opening position. If the switch to be selected is the first An air switch QF1, the process of closing the ring and selecting the jump is as follows:

First, reverse the jumper switch to the QF1 position, that is, connect the first group of contacts 35 of the jumper switch;

Secondly, close the third air switch QF3, the auxiliary contact 21 of the first air switch QF1, the auxiliary contact 22 of the second air switch QF2 and the auxiliary contact 23 of the third air switch QF3 are in the closed state, and the ring is closed. The start circuit is connected;

Finally, the relay coil 24 is energized, so that the four normally open contacts of the relay are closed at the same time. Since the first group of contacts 35 of the selector switch is in the on state, the opening circuit of the first air switch QF1 connected to it will The opening coil is energized, and the opening iron core moves, so that the main contact of the first air switch QF1 automatically jumps away.

In this embodiment, according to the principle of selecting and jumping the first air switch QF1, the second to sixth combination modes of automatic jump selection can be completed.

In this embodiment, after the air switch is selected and tripped, it is often necessary to restore the original operation mode. Take the restoration of the original operation mode of the above-mentioned selected jump selection combination mode as an example for illustration. The process is as follows:

First, reverse the jumper switch to the QF3 position, that is, connect the third group of contacts 37 of the jumper switch;

Secondly, close the first air switch QF1, the auxiliary contact 21 of the first air switch QF1, the auxiliary contact 22 of the second air switch QF2 and the auxiliary contact 23 of the third air switch QF3 are in the closed state, and the ring is closed. The start circuit is connected;

Finally, the relay coil 24 is energized, so that the four normally open contacts of the relay are closed at the same time. Since the third group of contacts 37 of the selector switch is in the on state, the opening circuit of the third air switch QF3 connected with it The opening coil is energized, and the opening iron core moves, so that the main contact of the third air switch QF3 automatically jumps off, thus restoring the original operation mode.

From the above description, it can be seen that the low-voltage loop closing and tripping system of the present invention adopts the switching operation mode of starting with low-voltage loop closing and automatically performing selective tripping, which not only avoids the occurrence of voltage flicker due to instantaneous power failure, but also ensures It ensures the reliability of power supply and the personal safety of operators, and at the same time greatly shortens the time for the original single power supply system to become a dual power supply system. If the device fails or the sensitivity changes, the measured power supply voltage difference on both sides is not greater than 5% of the rated voltage, and the measured loop closing current is basically between 30-40% of the rated current. The closing loop current exceeds the protection setting value, causing the protection on the power supply side to operate.

The above descriptions are only preferred embodiments of the present invention, and are not intended to limit the present invention. For those skilled in the art, the present invention may have various modifications and changes. 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 (7)

1. A low-voltage ring-closing and jump-selecting system is used for the jump-selection control after the ring is closed to three air switches in the dual power supply system of the single-bus section wiring form, and is characterized in that, comprising: Auxiliary contacts of three air switches; Relay, containing three normally open contacts; Selector switch, including three groups of contacts and only one group of contacts is in the ON state at a time; Among the three air switches, the auxiliary contacts of the first air switch, the second air switch and the third air switch are sequentially connected in series, wherein the auxiliary contact of the first air switch is connected with the low-voltage loop closing and jumping system. The live wire of the power supply is connected, the auxiliary contact of the third air switch is connected in series with the first end of the coil of the relay, and the second end of the coil of the relay is connected with the neutral wire of the power supply; The three normally open contacts of the relay are respectively connected to the three input contacts of the three sets of contacts of the selector switch, and the three output contacts of the three sets of contacts of the selector switch are connected to the three sets of contacts respectively. The opening coil connection of the three opening circuits of the air switch, Wherein, the relay is an electromagnetic solenoid structure. 2. The low-voltage loop closing and tripping system according to claim 1, characterized in that a fuse is also arranged between the auxiliary contact of the first air switch and the live wire of the power supply. 3. The low-voltage ring closing and jumping system according to claim 1, characterized in that, the relay also includes a fourth normally open contact, which is connected with a working indicator light for sending a ring closing signal. 4. The low-voltage ring closing and jumping system according to claim 3, wherein the relay is an AC intermediate relay. 5. The low-voltage ring closing and jumping system according to claim 4, characterized in that the rated voltage of the AC intermediate relay is AC220V. 6. The low-voltage loop closing and jumping system according to claim 4, characterized in that, the AC intermediate relay is a multi-contact AC intermediate relay with an electromagnetic solenoid structure. 7. The low-voltage loop closing and jumping system according to any one of claims 1 to 6, characterized in that, the three air switches are all universal air switches.