Electrical control mutual standby switching device

Abstract

The utility model relates to an electrical control mutual standby switching device, comprising a cabinet body and a switching circuit, the cabinet body is cooperatively used with a frequency converter and a soft start, the switching circuit comprises a contactor KM1, a contactor KM2, a contactor KM3, a contactor KM4, an isolation switch QS1, an isolation switch QS2, a mode selection change-over switch SA, relays K1-K4, and signal lamps HD1-HD6; the KM1, the KM2, the KM3, the KM4, the QS1 and the QS2 are located in the cabinet body, the K1-K4 are located in a control area of the cabinet body, and the SA, the HD1-HD6 are located outside the cabinet body. The device can realize quick switching and mutual standby of the two electric control systems, and can quickly cut off fault equipment and start standby equipment, so that smooth production of the blast furnace is guaranteed.

Description

Technical Field

[0001] This patent application belongs to the technical field of electrical switching equipment, and more specifically, relates to a switching device with electrical controls that serve as a backup for each other. Background Art

[0002] The blast furnace process generally consists of a charging system, air supply system, cooling system, gas recovery and dust removal system, and slag and iron discharge system. It is a highly continuous production process. To ensure production continuity and safety, key high-voltage equipment must have backup equipment. When production equipment fails, the ability to quickly and safely activate the backup equipment determines the continuity of blast furnace production.

[0003] When a high-voltage device or control system fails and an emergency switch to a backup device or backup control system is required, the disconnector is usually manually operated on the switch cabinet. However, manual operation takes a long time in an emergency, and errors may occur due to anxiety, lack of proficiency, or psychological quality, leading to high-voltage short circuits and other accidents, further expanding the low-voltage accident in the power grid. Therefore, how to quickly and safely switch equipment is a major issue that needs to be addressed. Utility Model Content

[0004] The technical problem to be solved by the utility model is to provide a switching device with electrical controls serving as backup for each other, which can realize rapid mutual switching of equipment, improve the continuity, reliability and safety of equipment operation, and avoid the expansion of voltage accidents.

[0005] In order to solve the above problems, the technical solution adopted by the present invention is:

[0006] An electrically controlled switching device serving as a backup for each other includes: a 1# motor soft start contactor KM1, a 1# motor variable frequency start contactor KM2, a 2# motor soft start contactor KM3, a 2# motor variable frequency start contactor KM4, a 1# motor electromagnetic isolating switch QS1, a 2# motor electromagnetic isolating switch QS2, a starting mode conversion switch SA, a 1# motor soft start relay K1, a 1# motor variable frequency start relay K2, a 2# motor soft start relay K3, a 2# motor variable frequency start relay K4, a 1# motor soft start indicator HD1, a 1# motor variable frequency start indicator HD2, a 2# motor soft start indicator HD3, a 2# motor variable frequency start indicator HD4, a 1# motor electromagnetic isolating switch indicator HD5, and a 2# motor electromagnetic isolating switch indicator HD6;

[0007] The lower end of the 1# motor soft start contactor KM1 is connected to the soft start cabinet, and the upper end is connected to the upper end of the 1# motor electromagnetic isolation switch QS1; the lower end of the 1# motor electromagnetic isolation switch QS1 is connected to the 1# motor; the lower end of the 1# motor variable frequency starting contactor KM2 is connected to the frequency converter cabinet, and the upper end is connected to the upper end of the 1# motor electromagnetic isolation switch QS1;

[0008] The lower end of the 2# motor soft start contactor KM3 is connected to the soft start cabinet, and the upper end is connected to the upper end of the 2# motor electromagnetic isolation switch QS2; the lower end of the 2# motor electromagnetic isolation switch QS2 is connected to the 2# motor; the lower end of the 2# motor variable frequency starting contactor KM4 is connected to the frequency converter cabinet, and the upper end is connected to the upper end of the 2# motor electromagnetic isolation switch QS2;

[0009] The starting mode transfer switch SA includes a first normally open point SA1, a second normally open point SA2, a third normally open point SA3, and a fourth normally open point SA4. One end of the first normally open point SA1 is connected to one end of the 220V power supply, and the other end is connected to the upper end of the normally closed point of the 1# motor variable frequency starting relay K2. The lower end of the normally closed point of relay K2 is connected to the upper end of the normally closed point of the 2# motor soft start starting relay K3. The lower end of the normally closed point of relay K3 is connected to the upper end of the normally closed point of the 2# motor variable frequency starting relay K4. The lower end of the normally closed point of relay K4 is connected to one end of the coil of the 1# motor soft start starting relay K1. The other end of the coil of relay K1 is connected to the other end of the 220V power supply.

[0010] One end of the second normally open point SA2 of the start mode transfer switch is connected to one end of the 220V power supply, and the other end is connected to the upper end of the normally closed point of the 1# motor soft start relay K1. The lower end of the normally closed point of relay K1 is connected to the upper end of the normally closed point of the 2# motor soft start relay K3. The lower end of the normally closed point of relay K3 is connected to the upper end of the normally closed point of the 2# motor variable frequency start relay K4. The lower end of the normally closed point of relay K4 is connected to one end of the coil of the 1# motor variable frequency start relay K2. The other end of the coil of relay K2 is connected to the other end of the 220V power supply.

[0011] One end of the third normally open point SA3 of the start mode transfer switch is connected to one end of the 220V power supply, and the other end is connected to the upper end of the normally closed point of the 1# motor soft start relay K1. The lower end of the normally closed point of relay K1 is connected to the upper end of the normally closed point of the 1# motor variable frequency start relay K2. The lower end of the normally closed point of relay K2 is connected to the upper end of the normally closed point of the 2# motor variable frequency start relay K4. The lower end of the normally closed point of relay K4 is connected to one end of the coil of the 2# motor soft start relay K3. The other end of the coil of relay K3 is connected to the other end of the 220V power supply.

[0012] One end of the fourth normally open point SA4 of the start mode transfer switch is connected to one end of the 220V power supply, and the other end is connected to the upper end of the normally closed point of the 1# motor soft start relay K1. The lower end of the normally closed point of relay K1 is connected to the upper end of the normally closed point of the 1# motor variable frequency start relay K2. The lower end of the normally closed point of relay K2 is connected to the upper end of the normally closed point of the 2# motor soft start relay K3. The lower end of the normally closed point of relay K3 is connected to one end of the coil of the 2# motor variable frequency start relay K4. The other end of the coil of relay K4 is connected to the other end of the 220V power supply.

[0013] Connect one end of the normally open point of the 1# motor soft start relay K1 to one end of the 220V power supply, and the other end to one end of the 1# motor soft start contactor KM1 coil, and the other end of the KM1 coil to the other end of the 220V power supply;

[0014] One end of the normally open point of the 1# motor variable frequency starting relay K2 is connected to one end of the 220V power supply, and the other end is connected to one end of the 1# motor variable frequency starting contactor KM2 coil, and the other end of the KM2 coil is connected to the other end of the 220V power supply;

[0015] Connect one end of the normally open point of the 2# motor soft start relay K3 to one end of the 220V power supply, and the other end to one end of the coil of the 2# motor soft start contactor KM3, and the other end of the KM3 coil to the other end of the 220V power supply;

[0016] One end of the normally open point of the 2# motor variable frequency starting relay K4 is connected to one end of the 220V power supply, and the other end is connected to one end of the 2# motor variable frequency starting contactor KM4 coil, and the other end of the KM4 coil is connected to the other end of the 220V power supply;

[0017] One end of the normally open contact of the 1# motor soft start contactor KM1 is connected to one end of the 220V power supply, and the other end is connected to one end of the coil of the 1# motor electromagnetic isolation switch QS1. The other end of the QS1 coil is connected to the other end of the 220V power supply. The normally open point of the 1# motor variable frequency starting contactor KM2 is connected in parallel with the normally open point of KM1.

[0018] One end of the normally open contact of the 2# motor soft start contactor KM3 is connected to one end of the 220V power supply, and the other end is connected to one end of the coil of the 2# motor electromagnetic isolation switch QS2. The other end of the QS2 coil is connected to the other end of the 220V power supply. The normally open point of the 2# motor variable frequency starting contactor KM4 is connected in parallel with the normally open point of KM3.

[0019] One end of the normally open contact of the 1# motor soft start contactor KM1 is connected to one end of the 220V power supply, and the other end is returned to the other end of the 220V power supply through the 1# motor soft start indicator HD1;

[0020] One end of the normally open point of the 1# motor variable frequency starting contactor KM2 is connected to one end of the 220V power supply, and the other end is returned to the other end of the 220V power supply through the 1# motor variable frequency starting indicator HD2;

[0021] One end of the normally open contact of the 2# motor soft start contactor KM3 is connected to one end of the 220V power supply, and the other end is returned to the other end of the 220V power supply through the 2# motor soft start indicator HD3;

[0022] One end of the normally open point of the 2# motor variable frequency starting contactor KM4 is connected to one end of the 220V power supply, and the other end is returned to the other end of the 220V power supply through the 2# motor variable frequency starting indicator HD4;

[0023] One end of the normally open point of the 1# motor electromagnetic isolating switch QS1 is connected to one end of the 220V power supply, and the other end is returned to the other end of the 220V power supply through the 1# motor electromagnetic isolating switch indicator HD5;

[0024] One end of the normally open point of the 2# motor electromagnetic isolation switch QS2 is connected to one end of the 220V power supply, and the other end returns to the other end of the 220V power supply through the 2# motor electromagnetic isolation switch indicator HD6.

[0025] Furthermore, the 1# motor soft start contactor KM1, the 1# motor variable frequency starting contactor KM2, the 2# motor soft start contactor KM3, and the 2# motor variable frequency starting contactor KM4 are all high-voltage contactors.

[0026] Furthermore, the 1# motor electromagnetic isolating switch QS1 and the 2# motor electromagnetic isolating switch QS2 are both isolating switches with built-in electromagnetic locks.

[0027] Due to the adoption of the above technical solution, the beneficial effects achieved by the utility model are:

[0028] This device realizes two groups of mutual backup: the soft start cabinet and the frequency conversion cabinet are mutual backup, and the 1# motor and the 2# motor are mutual backup. It is low-cost, easy to operate, and the parts are easy to replace. It is simple to use. Through the various indicator lights (HD1~HD6), it can be judged whether the contactor and electromagnetic isolation switch are in place. In the event of a fault, it can be switched quickly and safely. It not only improves the reliability of equipment operation, but also reduces the negative impact of equipment problems on the continuous production of blast furnaces. It has extremely high promotion and application value. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] Figure 1 This is the main circuit principle diagram of the utility model;

[0030] Figure 2 This is the control circuit principle diagram of the utility model;

[0031] in:

[0032] KM1, 1# motor soft start contactor; KM2, 1# motor variable frequency starting contactor; KM3, 2# motor soft start contactor; KM4, 2# motor variable frequency starting contactor; QS1, 1# motor electromagnetic isolating switch; QS2, 2# motor electromagnetic isolating switch; SA, starting mode conversion switch; SA1, first normally open point; SA2, second normally open point; SA3, third normally open point; SA4, fourth normally open point; K1, 1# motor soft start relay; K2, 1# motor variable frequency starting relay; K3, 2# motor soft start relay; K4, 2# motor variable frequency starting relay; HD1, 1# motor soft start indicator light; HD2, 1# motor variable frequency starting indicator light; HD3, 2# motor soft start indicator light; HD4, 2# motor variable frequency starting indicator light; HD5, 1# motor electromagnetic isolating switch indicator light; HD6, 2# motor electromagnetic isolating switch indicator light. DETAILED DESCRIPTION

[0033] The present invention will be described in further detail below with reference to the embodiments.

[0034] An electrical control switching device with mutual backup includes a cabinet and a switching circuit. The cabinet is used in conjunction with a frequency converter and a soft starter. The switching circuit includes 1# motor soft start starting contactor KM1, 1# motor variable frequency starting contactor KM2, 2# motor soft start starting contactor KM3, 2# motor variable frequency starting contactor KM4, 1# motor isolation switch QS1, 2# motor electromagnetic isolation switch QS2, mode selection switch SA, 1# motor soft start starting relay K1, 1# motor variable frequency starting relay K2, 2# motor soft start starting relay K3, 2# motor variable frequency starting relay K4, and signal lights HD1 to HD6.

[0035] The lower end of the 1# motor soft start contactor KM1 is connected to the soft start cabinet, and the upper end is connected to the upper end of the 1# motor electromagnetic isolation switch QS1; the lower end of the 1# motor electromagnetic isolation switch QS1 is connected to the 1# motor; the lower end of the 1# motor variable frequency starting contactor KM2 is connected to the frequency converter cabinet, and the upper end is connected to the upper end of the 1# motor electromagnetic isolation switch QS1;

[0036] The lower end of the 2# motor soft start contactor KM3 is connected to the soft start cabinet, and the upper end is connected to the upper end of the 2# motor electromagnetic isolation switch QS2; the lower end of the 2# motor electromagnetic isolation switch QS2 is connected to the 2# motor; the lower end of the 2# motor frequency conversion starting contactor KM4 is connected to the frequency converter cabinet, and the upper end is connected to the upper end of the 2# motor electromagnetic isolation switch QS2.

[0037] like Figure 1 、 Figure 2 , combined with Figure 1It can be seen that contactor KM1 and contactor KM2 are connected in parallel, contactor KM3 and contactor KM4 are connected in parallel, contactor KM1 and contactor KM3 are connected in parallel, and contactor KM2 and KM4 are connected in parallel.

[0038] At both ends of the 220V control circuit:

[0039] Connect the first normally closed contact of the 1# motor variable frequency starting relay K2, the first normally closed contact of the 2# motor soft start starting relay K3, the first normally closed contact of the 2# motor variable frequency starting relay K4, and the coil of the 1# motor soft start starting relay K1 in sequence;

[0040] Connect the first normally closed contact of the 1# motor soft start relay K1, the second normally closed contact of the 2# motor soft start relay K3, the second normally closed contact of the 2# motor variable frequency start relay K4, and the coil of the 1# motor variable frequency start relay K2 in sequence;

[0041] The second normally closed contact of the 1# motor soft start relay K1, the second normally closed contact of the 1# motor variable frequency start relay K2, the third normally closed contact of the 2# motor variable frequency start relay K4, and the coil of the 2# motor soft start relay K3 are connected in sequence;

[0042] The third normally closed contact of the 1# motor soft start relay K1, the third normally closed contact of the 1# motor variable frequency start relay K2, the third normally closed contact of the 2# motor soft start relay K3, and the coil of the 2# motor variable frequency start relay K4 are connected in sequence;

[0043] The starting mode conversion switch SA is respectively connected to the first normally closed contact of the 1# motor variable frequency starting relay K2, the first normally closed contact of the 1# motor soft starting relay K1, the second normally closed contact of the 1# motor soft starting relay K1, and the third normally closed contact of the 1# motor soft starting relay K1;

[0044] The first normally open contact of the 1# motor soft-start relay K1 is connected to the coil of the 1# motor soft-start contactor KM1; the first normally open contact of the 1# motor variable frequency starting relay K2 is connected to the coil of the 1# motor variable frequency starting contactor KM2; the first normally open contact of the 2# motor soft-start relay K3 is connected to the coil of the 2# motor soft-start contactor KM3; the first normally open contact of the 2# motor variable frequency starting relay K4 is connected to the coil of the 2# motor variable frequency starting contactor KM4;

[0045] The first normally open contact of the 1# motor soft start contactor KM1 and the first normally open contact of the 1# motor variable frequency start contactor KM2 are connected in parallel and then connected to the coil of the 1# motor electromagnetic isolation switch QS1;

[0046] The first normally open contact of the 2# motor soft start contactor KM3 and the first normally open contact of the 2# motor variable frequency start contactor KM4 are connected in parallel and then connected to the coil of the 2# motor electromagnetic isolation switch QS2;

[0047] The second normally open contact of the 1# motor soft start contactor KM1 is connected to the 1# motor soft start indicator light HD1; the second normally open contact of the 1# motor frequency conversion starting contactor KM2 is connected to the 1# motor frequency conversion starting indicator light HD2; the second normally open contact of the 2# motor soft start contactor KM3 is connected to the 2# motor soft start indicator light HD3; the second normally open contact of the 2# motor frequency conversion starting contactor KM4 is connected to the 2# motor frequency conversion starting indicator light HD4; the normally open contact of the 1# motor electromagnetic isolation switch QS1 is connected to the 1# motor electromagnetic isolation switch indicator light HD5; the normally open contact of the 2# motor electromagnetic isolation switch QS2 is connected to the 2# motor electromagnetic isolation switch indicator light HD6.

[0048] In terms of equipment selection, 1# motor soft start contactor KM1, 1# motor variable frequency starting contactor KM2, 2# motor soft start contactor KM3, and 2# motor variable frequency starting contactor KM4 are all high-voltage vacuum contactors.

[0049] 1# motor electromagnetic isolating switch QS1 and 2# motor electromagnetic isolating switch QS2 are both isolating switches with electromagnetic locks on the operating handles, which facilitate the high-voltage circuit to have a clear disconnect point when repairing standby equipment, ensuring personnel safety. The isolating switches with electromagnetic locks can prevent personnel from operating them incorrectly.

[0050] The starting mode conversion switch SA includes the first normally open point SA1 to the fourth normally open point SA4. The first normally open point SA1 is connected to the first normally closed contact of the 1# motor variable frequency starting relay K2. The second normally open point SA2 to the fourth normally open point SA4 are correspondingly connected to the first normally closed contact of the 1# motor soft start starting relay K1 to the third normally closed contact of the 1# motor soft start starting relay K1.

[0051] 1# motor soft start relay K1, 1# motor variable frequency start relay K2, 2# motor soft start relay K3, 2# motor variable frequency start relay K4 are common relays, such as Schneider relays. The switching of working modes is achieved by the attraction of K1-K4 relays.

[0052] Motor 1's soft start indicator (HD1), motor 1's variable frequency start indicator (HD2), motor 2's soft start indicator (HD3), motor 2's variable frequency start indicator (HD4), motor 1's electromagnetic isolating switch indicator (HD5), and motor 2's electromagnetic isolating switch indicator (HD6) are installed outside the power distribution cabinet. Indicators HD1 through HD4 indicate the operating mode, while indicators HD5 and HD6 indicate which motor is operating. Do not operate the isolating switch when these indicators are on.

[0053] 1# motor soft start contactor KM1, 1# motor variable frequency starting contactor KM2, 2# motor soft start contactor KM3, 2# motor variable frequency starting contactor KM4, 1# motor isolation switch QS1, 2# motor electromagnetic isolation switch QS2 are located in the cabinet, 1# motor soft start relay K1, 1# motor variable frequency starting relay K2, 2# motor soft start relay K3, 2# motor variable frequency starting relay K4 are located in the cabinet control area.

[0054] The mode selection switch SA, 1# motor soft start operation signal light HD1, 1# motor frequency conversion operation signal light HD2, 2# motor soft start operation signal light HD3, 2# motor frequency conversion operation signal light HD4, isolation switch 1# motor electromagnetic isolation switch indicator light HD5, 2# motor electromagnetic isolation switch indicator light HD6 are located outside the cabinet.

[0055] Combine Figure 2 The start mode selector switch SA has four positions: Mode 1 (corresponding to SA1), Mode 2 (corresponding to SA2), Mode 3 (corresponding to SA3), and Mode 4 (corresponding to SA4). Simply turn the switch to the desired mode to start the motor. Switching between the four operating modes is quick and easy.

[0056] When soft start of motor #1 is required, the start mode conversion switch SA is turned to mode 1, corresponding to the first normally open point SA1, the contactor KM1 is closed, the electromagnetic isolation switch QS1 is closed, the soft start indicator HD1 of motor #1 and the electromagnetic isolation switch indicator HD5 of motor #1 are on, and the soft start of motor #1 is successful.

[0057] When variable frequency starting of motor 1# is required, the starting mode conversion switch SA is turned to mode 2, corresponding to the second normally open point SA2, the contactor KM2 is closed, the electromagnetic isolation switch QS1 is closed, the variable frequency starting indicator HD2 of motor 1# and the electromagnetic isolation switch indicator HD5 of motor 1# are on, and the variable frequency starting of motor 1# is successful.

[0058] When soft start of motor 2# is required, the starting mode conversion switch SA is turned to mode 3 corresponding to the third normally open point SA3, the contactor KM3 is closed, the electromagnetic isolation switch QS2 is closed, the soft start indicator HD3 of motor 2# and the electromagnetic isolation switch indicator HD6 of motor 2# are on, and the soft start of motor 2# is successful.

[0059] When variable frequency starting of motor 2# is required, the starting mode conversion switch SA is turned to mode 4, corresponding to the fourth normally open point SA4, the contactor KM4 is closed, the electromagnetic isolation switch QS2 is closed, the variable frequency starting indicator HD4 of motor 2# and the electromagnetic isolation switch indicator HD6 of motor 2# are on, and the variable frequency starting of motor 2# is successful.

[0060] The working principle of this utility model is mainly divided into four situations:

[0061] (1) When it is necessary to soft-start the 1# motor, turn the starting mode conversion switch SA to the mode 1 position, that is, the first normally open point SA1 of the conversion switch is closed, the coil of the 1# motor soft-start relay K1 is energized, the normally open point of the relay K1 is closed, the coil of the 1# motor soft-start contactor KM1 is energized, the normally open point of the contactor KM1 is closed, the 1# motor electromagnetic isolation switch QS1 is closed, the 1# motor soft-start indicator HD1 and the 1# motor electromagnetic isolation switch indicator HD5 are on, and the 1# motor soft-start is successful.

[0062] (2) When variable frequency starting of motor 1# is required, the starting mode conversion switch SA is turned to mode 2, that is, the second normally open point SA2 of the conversion switch is closed, the coil of the variable frequency starting relay K2 of motor 1# is energized, the normally open point of relay K2 is closed, the coil of the soft start contactor KM2 of motor 1# is energized, the normally open point of contactor KM2 is closed, the electromagnetic isolating switch QS1 of motor 1# is closed, the variable frequency starting indicator HD1 of motor 1# and the indicator HD5 of electromagnetic isolating switch of motor 1# are on, and the variable frequency starting of motor 1# is successful.

[0063] (3) When it is necessary to soft-start the 2# motor, turn the starting mode conversion switch SA to the mode 3 position, that is, the third normally open point SA3 of the conversion switch is closed, the 2# motor soft-start relay K3 coil is energized, the relay K3 normally open point is closed, the 2# motor soft-start contactor KM3 coil is energized, the contactor KM3 normally open point is closed, the 2# motor electromagnetic isolation switch QS2 is closed, the 2# motor soft-start indicator HD3 and the 2# motor electromagnetic isolation switch indicator HD6 are on, and the 2# motor soft-start is successful.

[0064] (4) When variable frequency starting of motor 2 is required, the starting mode conversion switch SA is turned to mode 4, that is, the fourth normally open point SA4 of the conversion switch is closed, the coil of the variable frequency starting relay K4 of motor 2 is energized, the normally open point of relay K4 is closed, the coil of the variable frequency starting contactor KM4 of motor 2 is energized, the normally open point of contactor KM4 is closed, the electromagnetic isolating switch QS2 of motor 2 is closed, the variable frequency starting indicator HD4 of motor 2 and the indicator HD6 of electromagnetic isolating switch of motor 2 are on, and the variable frequency starting of motor 2 is successful.

Claims

1. A switching device for electrical control mutual backup, characterized in that: Including 1# motor soft start contactor KM1, 1# motor variable frequency starting contactor KM2, 2# motor soft start contactor KM3, 2# motor variable frequency starting contactor KM4, 1# motor electromagnetic isolating switch QS1, 2# motor electromagnetic isolating switch QS2, starting mode conversion switch SA, 1# motor soft start relay K1, 1# motor variable frequency starting relay K2, 2# motor soft start relay K3, 2# motor variable frequency starting relay K4, 1# motor soft start indicator HD1, 1# motor variable frequency starting indicator HD2, 2# motor soft start indicator HD3, 2# motor variable frequency starting indicator HD4, 1# motor electromagnetic isolating switch indicator HD5, 2# motor electromagnetic isolating switch indicator HD6; The lower end of the 1# motor soft start contactor KM1 is connected to the soft start cabinet, and the upper end is connected to the upper end of the 1# motor electromagnetic isolation switch QS1; the lower end of the 1# motor electromagnetic isolation switch QS1 is connected to the 1# motor; the lower end of the 1# motor variable frequency starting contactor KM2 is connected to the frequency converter cabinet, and the upper end is connected to the upper end of the 1# motor electromagnetic isolation switch QS1; The lower end of the 2# motor soft start contactor KM3 is connected to the soft start cabinet, and the upper end is connected to the upper end of the 2# motor electromagnetic isolation switch QS2; the lower end of the 2# motor electromagnetic isolation switch QS2 is connected to the 2# motor; the lower end of the 2# motor variable frequency starting contactor KM4 is connected to the frequency converter cabinet, and the upper end is connected to the upper end of the 2# motor electromagnetic isolation switch QS2; At both ends of the 220V control circuit: The first normally closed contact of the 1# motor variable frequency starting relay K2, the first normally closed contact of the 2# motor soft starting relay K3, the first normally closed contact of the 2# motor variable frequency starting relay K4, and the coil of the 1# motor soft starting relay K1 are connected in sequence; The first normally closed contact of the 1# motor soft start relay K1, the second normally closed contact of the 2# motor soft start relay K3, the second normally closed contact of the 2# motor variable frequency start relay K4, and the coil of the 1# motor variable frequency start relay K2 are connected in sequence; The second normally closed contact of the 1# motor soft start relay K1, the second normally closed contact of the 1# motor variable frequency start relay K2, the third normally closed contact of the 2# motor variable frequency start relay K4, and the coil of the 2# motor soft start relay K3 are connected in sequence; The third normally closed contact of the 1# motor soft start relay K1, the third normally closed contact of the 1# motor variable frequency start relay K2, the third normally closed contact of the 2# motor soft start relay K3, and the coil of the 2# motor variable frequency start relay K4 are connected in sequence; The start mode conversion switch SA is respectively connected to the first normally closed contact of the 1# motor variable frequency start relay K2, the first normally closed contact of the 1# motor soft start start relay K1, the second normally closed contact of the 1# motor soft start start relay K1, and the third normally closed contact of the 1# motor soft start start relay K1; The first normally open contact of the 1# motor soft start relay K1 is connected to the coil of the 1# motor soft start contactor KM1; The first normally open contact of the 1# motor variable frequency starting relay K2 is connected to the coil of the 1# motor variable frequency starting contactor KM2; The first normally open contact of the 2# motor soft start relay K3 is connected to the coil of the 2# motor soft start contactor KM3; the first normally open contact of the 2# motor variable frequency start relay K4 is connected to the coil of the 2# motor variable frequency start contactor KM4; The first normally open contact of the 1# motor soft start contactor KM1 and the first normally open contact of the 1# motor variable frequency start contactor KM2 are connected in parallel and connected to the coil of the 1# motor electromagnetic isolation switch QS1; The first normally open contact of the 2# motor soft start contactor KM3 and the first normally open contact of the 2# motor variable frequency start contactor KM4 are connected in parallel and connected to the coil of the 2# motor electromagnetic isolation switch QS2; The second normally open contact of the 1# motor soft start contactor KM1 is connected to the 1# motor soft start indicator HD1; the second normally open contact of the 1# motor variable frequency start contactor KM2 is connected to the 1# motor variable frequency start indicator HD2; The second normally open contact of the 2# motor soft start contactor KM3 is connected to the 2# motor soft start indicator light HD3; the second normally open contact of the 2# motor variable frequency start contactor KM4 is connected to the 2# motor variable frequency start indicator light HD4; the normally open contact of the 1# motor electromagnetic isolation switch QS1 is connected to the 1# motor electromagnetic isolation switch indicator light HD5; the normally open contact of the 2# motor electromagnetic isolation switch QS2 is connected to the 2# motor electromagnetic isolation switch indicator light HD6.

2. The electrical control switching device for mutual backup according to claim 1, characterized in that: 1# motor soft start contactor KM1, 1# motor variable frequency starting contactor KM2, 2# motor soft start contactor KM3, 2# motor variable frequency starting contactor KM4 are all high-voltage vacuum contactors.

3. The electrical control switching device for mutual backup according to claim 2, characterized in that: 1# motor electromagnetic isolating switch QS1 and 2# motor electromagnetic isolating switch QS2 are both isolating switches with electromagnetic locks on the operating handles.

4. An electrical control switching device for mutual backup according to any one of claims 1 to 3, characterized in that: The starting mode conversion switch SA includes a first normally open point SA1 to a fourth normally open point SA4. The first normally open point SA1 is connected to the first normally closed contact of the 1# motor variable frequency starting relay K2. The second normally open point SA2 to the fourth normally open point SA4 are correspondingly connected to the first normally closed contact of the 1# motor soft starting relay K1 to the third normally closed contact of the 1# motor soft starting relay K1.

5. The electrical control mutual backup switching device according to claim 4, characterized in that: 1# motor soft start relay K1, 1# motor variable frequency start relay K2, 2# motor soft start relay K3, 2# motor variable frequency start relay K4 are Schneider relays, and the switching of working modes is achieved by the attraction of K1-K4 relays.

6. The electrical control mutual backup switching device according to claim 4, characterized in that: 1# motor soft start indicator HD1, 1# motor variable frequency start indicator HD2, 2# motor soft start indicator HD3, 2# motor variable frequency start indicator HD4, 1# motor electromagnetic isolation switch indicator HD5, 2# motor electromagnetic isolation switch indicator HD6 are installed outside the distribution cabinet.

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