CN211455045U

CN211455045U - Spare power automatic switching simulation teaching screen

Info

Publication number: CN211455045U
Application number: CN202020235988.0U
Authority: CN
Inventors: 马海艳; 毕雨; 周凯; 王雪姣; 徐芃
Original assignee: Veolia Harbin Thermal Power Co Ltd
Current assignee: Veolia Harbin Thermal Power Co Ltd
Priority date: 2020-02-26
Filing date: 2020-02-26
Publication date: 2020-09-08
Anticipated expiration: 2030-02-26

Abstract

The utility model discloses a spare power automatic switching emulation teaching screen, the connected mode of each components and parts is: 1# inlet wire circuit breaker pilot lamp 2, 2# inlet wire circuit breaker pilot lamp 3, the one end of segmentation circuit breaker pilot lamp 4 is parallelly connected to the positive power supply end of controlling 7 outputs of air circuit breaker, 1# inlet wire circuit breaker closes the position, 2# inlet wire circuit breaker closes the position, segmentation circuit breaker divides the position, 1 section generating line has the pressure, 2 section generating line have press carry on logic with after through the settlement charge time delay input to the set end of RS trigger, the output information of RS trigger, it accomplishes to be equipped with to throw charging certainly. The utility model discloses effectively solve each electric test company, colleges and universities or training agency to being equipped with relevant training problems such as haulage oneself willingly into the experiment fully.

Description

Spare power automatic switching simulation teaching screen

Technical Field

The utility model relates to a spare power automatic switching simulation teaching screen and spare power automatic switching logic judgment method.

Background

In the electrical operation of a power plant and a substation, in order to ensure the reliability of the power supply of the double power supplies, a spare power automatic switching device is generally arranged, and when one of the double power supplies loses power, the spare power automatic switching device automatically cuts off a fault power supply and puts a voltage-loss bus into a fault-free power supply loop. In order to ensure the reliability of power supply, once the equipment is put into operation, the equipment is not allowed to be subjected to a spare power automatic switching test except for short-time maintenance.

At present, some existing simulation teaching systems for related equipment of power plants and substations in the market are mostly practical training equipment for related control systems of motors, electricians, PLCs and the like, and at present, related practical training equipment for spare power automatic switching functions, principles, action logics, transmission tests and the like is unavailable.

Disclosure of Invention

The utility model aims at providing a be equipped with and automatically switch on emulation teaching screen can be to training institutions such as the well high-grade colleges and universities or each well high-grade technician that electric operation personnel such as power plant, electric substation or have electric specialty to the device experiment etc. of being equipped with and automatically switching on teaching. The technical scheme of the utility model is that: a spare power automatic switching simulation teaching screen is characterized in that a front panel of a cabinet body (1) is of a detachable structure; the automatic power supply system comprises a 1# incoming line breaker indicator lamp (2), a 2# incoming line breaker indicator lamp (3), a segmented breaker indicator lamp (4), a spare power automatic switching device (5), a power supply air circuit breaker (6), a control air circuit breaker (7), a first incoming line voltage circuit breaker (8), a second incoming line voltage circuit breaker (9), a first bus voltage circuit breaker (10), a second bus voltage circuit breaker (11), a first control switch (12), a second control switch (13), a third control switch (14) and a position selecting switch (15) which are all installed on a panel of a cabinet body (1), and a terminal block (16), a first intermediate relay (17), a second intermediate relay (18) and a third intermediate relay (19) are installed inside the cabinet body (1); the connection mode of each component is as follows: the air circuit breaker comprises a 1# incoming line circuit breaker indicator lamp (2), a 2# incoming line circuit breaker indicator lamp (3) and a segmented circuit breaker indicator lamp (4), wherein one end of the 1# incoming line circuit breaker indicator lamp (2), one end of the 2# incoming line circuit breaker indicator lamp (3) is connected to a positive power source end for controlling the output of an air circuit breaker (7) in parallel, a normally open contact of a second intermediate relay (18) and a normally closed contact of the second intermediate relay (18) are respectively connected with two input ends of the 1# incoming line circuit breaker indicator lamp (2) in series, a normally open contact of a first intermediate relay (17) and a normally closed contact of the first intermediate relay (17) are respectively connected with two input ends of the 2# incoming line circuit breaker indicator lamp (3) in series, and a normally open contact of a third intermediate relay (19) and a normally closed; the power supply air circuit breaker (6) is connected with the power supply input end of the spare power automatic switching device (5); the input end of a first incoming line voltage breaker (8) is connected with a 1# incoming line voltage through a terminal row (16), the input end of a second incoming line voltage breaker (9) is connected with a 2# incoming line voltage through the terminal row (16), the input end of a first bus voltage breaker (10) is connected with a 1-section bus voltage through the terminal row (16), and the input end of a second bus voltage breaker (11) is connected with a 2-section bus voltage through the terminal row (16); the output end of a first incoming line voltage breaker (8) is connected to the No. 1 incoming line voltage input end of a spare power automatic switching device (5), the output end of a second incoming line voltage breaker (9) is connected to the No. 2 incoming line voltage input end of the spare power automatic switching device (5), the output end of a first bus voltage breaker (10) is connected to the No. 1 bus voltage input end of the spare power automatic switching device (5), and the output end of a second bus voltage breaker (11) is connected to the No. 2 bus voltage input end of the spare power automatic switching device (5); auxiliary contacts of a first control switch (12), a second control switch (13), a third control switch (14) and a position selecting switch (15) are respectively connected to a switching value input end of the spare power automatic switching device (5); the outlet of the spare power automatic switching device (5) is connected to the terminal block (16).

The utility model discloses a theory of operation:

as can be seen from fig. 2, the standby power automatic switching device 5 is accessed with the 1# incoming line voltage, the 1# incoming line current, the 2# incoming line voltage, the 2# incoming line current, the 1-section bus voltage, the 2-section bus voltage, and the segmented current as the basis for determining the incoming line voltage, the current, and the bus voltage by the standby power automatic switching device 5; when the miniature voltage circuit breakers normally operate, the miniature voltage circuit breakers are required to be in a closing state;

as can be seen from fig. 3, the position of the 1# incoming line breaker, the position of the 2# incoming line breaker, the position of the sectionalized breaker, the spare power automatic switching input, the 1# incoming line protection trip, the 1# incoming line manual trip, the 1# incoming line remote control trip, the 2# incoming line protection trip, the 2# incoming line manual trip, and the 2# incoming line remote control trip are connected to the spare power automatic switching device as the basis of the spare power automatic switching charging/discharging and action; when the device normally operates, the position selecting switch is rotated to the input position;

as shown in fig. 4, according to the control principle of the # 1 incoming line breaker, the # 2 incoming line breaker, the sectional breaker, the # 1 incoming line breaker position indicator, the # 2 incoming line breaker position indicator and the sectional breaker position indicator, when the air circuit breaker 7 is controlled to be closed, the first intermediate relay 17 does not act, the normally open contact corresponding to the first intermediate relay 17 is opened, the normally closed contact is closed, the green light of the # 1 incoming line breaker indicator 2 is on, the 1# incoming line breaker is off, the second intermediate relay 18 does not act, the normally open contact corresponding to the second intermediate relay 18 is opened, the normally closed contact is closed, the green light of the # 2 incoming line breaker indicator 3 is on, the 2# incoming line breaker is off, the third intermediate relay 19 does not act, the normally open contact corresponding to the third intermediate relay 19 is opened, the normally closed contact is closed, the sectional breaker indicator 4 is on, the position of the sectional breaker is shown, when the first control switch 12 is rotated to be closed, the closing contact of the first control switch 12 is closed, the action of the first intermediate relay 17 is realized, the auxiliary contact of the first intermediate relay 17 is closed, a self-holding loop is formed, at the moment, the 1# incoming line breaker indicator light 2 is changed from green to red, the position of the 1# incoming line breaker is shown, when the second control switch 13 is rotated to be closed, the closing contact of the second control switch 13 is closed, the action of the second intermediate relay 18 is realized, the auxiliary contact of the second intermediate relay 18 is closed, the self-holding loop is formed, at the moment, the 2# incoming line breaker indicator light 3 is changed from green to red, and the position of the 2# incoming line breaker is shown.

As can be seen from fig. 5, when the backup automatic switching device detects that the 1# incoming line breaker is closed, the 2# incoming line breaker is closed, the segmented breaker is separated, the 1-segment bus has voltage, and the 2-segment bus has voltage, and after a set delay time, the backup automatic switching charging completion information is sent out, and the backup automatic switching ready indicator light corresponding to the backup automatic switching device 5 is turned on;

as can be seen from fig. 6, the backup power automatic switching device is ready, when the backup power automatic switching device 5 detects that the 1# incoming line is not voltage and has no current, and the 2-section bus has voltage, a jump 1# incoming line command is issued after action delay, at this time, a normally closed contact of a jump 1# incoming line outlet of the backup power automatic switching device 5 in fig. 4 is opened, the first intermediate relay 17 is reset, the 1# incoming line breaker indicator lamp 2 is changed from red to green, at this time, the backup power automatic switching device 5 detects that the 1# incoming line is jumped, a closing and opening section command is issued, a closing and opening section outlet of the backup power automatic switching device 5 is closed, the third intermediate relay 19 acts, a normally open contact is closed to form a self-holding loop, the section breaker indicator lamp 4 is changed from green to red to indicate that the section breaker is closed, the backup power automatic switching device succeeds, and when the backup power automatic switching device 5 issues a jump 1# incoming.

As can be seen from fig. 7, the backup power automatic switching device is ready, when the backup power automatic switching device 5 detects that the 2# incoming line is not voltage and has no current, and the 1-section bus has voltage, a jump 2# incoming line command is issued after action delay, at this time, a normally closed contact of a jump 2# incoming line outlet of the backup power automatic switching device 5 in fig. 4 is opened, the second intermediate relay 18 is reset, the 2# incoming line breaker indicator lamp 3 is changed from red to green, at this time, the backup power automatic switching device 5 detects that the 2# incoming line is jumped, a closing and opening section command is issued, a closing and opening section outlet of the backup power automatic switching device 5 is closed, the third intermediate relay 19 acts, a normally open contact is closed, a self-holding loop is formed, the section breaker indicator lamp 4 is changed from green to red, indicating that the section breaker is closed, the backup power automatic switching device succeeds, and when the backup power automatic switching device 5 issues a jump 2 #.

As can be seen from fig. 5, when the backup automatic switching device 5 detects any information of the 1# incoming line breaker open position, the 2# incoming line breaker open position, the sectionalized breaker closed position, the 1-section bus no voltage, the 2-section bus no voltage, the exit of the position selecting switch, the backup automatic switching failure, or the incoming line hand trip/microcomputer trip/protection trip, the RS trigger is reset, and the backup automatic switching ready indicator of the backup automatic switching device 5 is reset; only when the spare power automatic switching ready condition is loaded again, the spare power automatic switching ready indicator lamp is lightened;

the utility model discloses realize the function of training, demonstration, examination such as stand-by automatic switching knowledge picture, experiment, action logic.

The utility model discloses technological effect:

the utility model is to solve the problem of dual supply automatic switch-over teaching, through the skill training of this teaching screen, can be when deep understanding professional technical knowledge, cultivate the student to power automatic switch-over wiring and action principle understand and master. The device is suitable for the study, teaching, examination and other contents of middle and high-tech electrical professional students. The characteristics are as follows:

1. the system has perfect and reasonable structure, the front panel can be detached, and internal wiring is convenient. External wiring passes through the terminal row and inserts, during the teaching, need not to change the inside wiring of teaching screen, and external wiring is simple, convenient.

2. The student can monitor the states of the incoming line and the bus coupler circuit breaker and the charging and discharging and action sequence of the spare power automatic switching device, the running state and the like in real time through the front indicator lamp of the teaching screen and the screen of the spare power automatic switching device.

3. The teaching screen is provided with the spare power automatic switching device, the incoming line and the bus-bar circuit breaker indicator lamp, the vacuum circuit breaker is replaced by a relay, other devices and action logics are consistent with those of field devices, and the field actual devices are highly restored.

4. The relay is adopted to replace a vacuum circuit breaker, so that the cost is reduced and the vacuum circuit breaker is more economical.

5. The teaching of the teaching screen enhances the practical ability of the student and the understanding of the spare power automatic switching action logic, has strong pertinence, and further improves the technical ability of the student.

Drawings

FIG. 1 is the overall structure diagram of the present invention

FIG. 2 is a wiring diagram for analog input of the present invention

FIG. 3 is a diagram of the switching value input wiring of the present invention

Fig. 4 the utility model discloses a control principle wiring diagram

Fig. 5 is a logic diagram of charging and discharging of the present invention

Fig. 6 is a logic diagram of the standby power automatic switching operation of 1-section bus under voltage loss

Fig. 7 is a logic diagram of the operation of the backup power automatic switching device with 2-segment bus under voltage loss

Detailed Description

A spare power automatic switching simulation teaching screen is shown in figure 1, wherein a front panel of a cabinet body 1 is of a detachable structure; the automatic switching system comprises a 1# incoming line breaker indicator lamp 2, a 2# incoming line breaker indicator lamp 3, a segmented breaker indicator lamp 4, a spare power automatic switching device 5, a power supply air circuit breaker 6, a control air circuit breaker 7, a first incoming line voltage circuit breaker 8, a second incoming line voltage circuit breaker 9, a first bus voltage circuit breaker 10, a second bus voltage circuit breaker 11, a first control switch 12, a second control switch 13, a third control switch 14 and a position selecting switch 15, wherein the first incoming line circuit breaker indicator lamp, the second incoming line circuit breaker indicator lamp, the third bus voltage circuit breaker and the position selecting switch are all installed on a panel of a cabinet body 1, and a terminal block 16, a first intermediate relay; the connection mode of each component is as follows: the air circuit breaker comprises a 1# incoming line circuit breaker indicator lamp 2, a 2# incoming line circuit breaker indicator lamp 3 and a segmented circuit breaker indicator lamp 4, wherein one end of the 1# incoming line circuit breaker indicator lamp 2, one end of the 2# incoming line circuit breaker indicator lamp 3 and one end of the segmented circuit breaker indicator lamp 4 are connected in parallel to a positive power source end for controlling the output of an air circuit breaker 7, a normally open contact of a second intermediate relay 18 and a normally closed contact of the second intermediate relay 18 are respectively connected with two input ends of the 1# incoming line circuit breaker indicator lamp 2 in series, a normally open contact of a first intermediate relay 17 and a normally closed contact of the first intermediate relay 17 are respectively connected with two input ends of the 2# incoming line circuit breaker indicator lamp 3 in series, and a normally; the power supply air circuit breaker 6 is connected with the power supply input end of the spare power automatic switching device 5; the input end of the first incoming line voltage breaker 8 is connected with the 1# incoming line voltage through the terminal block 16, the input end of the second incoming line voltage breaker 9 is connected with the 2# incoming line voltage through the terminal block 16, the input end of the first bus voltage breaker 10 is connected with the 1-section bus voltage through the terminal block 16, and the input end of the second bus voltage breaker 11 is connected with the 2-section bus voltage through the terminal block 16; the output end of the first incoming line voltage circuit breaker 8 is connected to the 1# incoming line voltage input end of the backup automatic switching device 5, the output end of the second incoming line voltage circuit breaker 9 is connected to the 2# incoming line voltage input end of the backup automatic switching device 5, the output end of the first bus voltage circuit breaker 10 is connected to the 1-section bus voltage input end of the backup automatic switching device 5, and the output end of the second bus voltage circuit breaker 11 is connected to the 2-section bus voltage input end of the backup automatic switching device 5; auxiliary contacts of the first control switch 12, the second control switch 13, the third control switch 14 and the position selecting switch 15 are respectively connected to a switching value input end of the spare power automatic switching device 5; the outlet of the backup power automatic switching device 5 is connected to the terminal block 16.

A spare power automatic switching logic judgment method of a spare power automatic switching simulation teaching screen is characterized in that a spare power automatic switching device 5 is used for carrying out spare power automatic switching action logic judgment, and internal judgment logic is as follows:

1) spare power automatic switching charging conditions: the method comprises the following steps that 1# incoming line breaker closing position, 2# incoming line breaker closing position, segmented breaker opening position, 1-section bus pressing, 2-section bus pressing for logic and then inputting to a setting end of an RS trigger after set charging delay, information is output by an output end of the RS trigger, and spare power automatic switching charging is completed;

2) the discharge conditions of the spare power automatic switch are as follows: the method comprises the following steps that 1# incoming line circuit breaker is separated, 2# incoming line circuit breaker is separated, segmented circuit breaker is closed, 1 section of bus is not in voltage, 2 section of bus is not in voltage logic or is subjected to set discharge delay to be tripped with 1# incoming line protection, 1# incoming line hand trip, 1# incoming line remote control trip, 2# incoming line protection trip, 2# incoming line hand trip, 2# incoming line remote control trip, segmented wave Arger action, spare power automatic switching quit, and spare power automatic switching failure is logically input or is input to a reset end of an RS trigger;

3) the action logic of the spare power automatic switching device is as follows: when the No. 1 incoming line has no fault and no voltage, the charging of the spare power automatic switching is detected to be completed, the No. 1 incoming line has no voltage and no current, the No. 2 incoming line has a voltage logic and then sends out a No. 1 incoming line jumping command through set action delay, and simultaneously carries out logic AND with the No. 1 incoming line jumping position and then outputs a switching subsection command, and the No. 1 incoming line jumping command and the No. 1 incoming line merging position logic are then delayed to output the failure information of the spare power automatic switching; when the 2# incoming line has no fault and no voltage, the charging of the spare power automatic switching is detected to be completed, the 2# incoming line has no voltage and no current, the 1# incoming line has voltage logic and then sends out a jump 2# incoming line command through set action delay, and simultaneously carries out logic AND with the 2# incoming line jump position and then outputs a switching and sectioning command, and the jump 2# incoming line command and the 2# incoming line switch-in position logic are then output with delay, thereby outputting the failure information of the spare power automatic switching.

The specific working process is as follows: as shown in fig. 1, a # 1 incoming line breaker indicator lamp 2, a # 2 incoming line breaker indicator lamp 3, a sectionalized breaker indicator lamp 4, a spare power automatic switching device 5, a power supply air circuit breaker 6, a control air circuit breaker 7, a first incoming line voltage circuit breaker 8, a second incoming line voltage circuit breaker 9, a first bus voltage circuit breaker 10, a second bus voltage circuit breaker 11, a first control switch 12, a second control switch 13, a third control switch 14, and a position selecting switch 15 are all installed on a panel of a cabinet body 1, and a terminal strip 16, a first intermediate relay 17, a second intermediate relay 18, and a third intermediate relay 19 are installed inside the cabinet body 1; as shown in fig. 2, the power supply air circuit breaker 6 is connected to a power supply input terminal of the backup automatic switching device 5; the input end of the first incoming line voltage breaker 8 is connected with the 1# incoming line voltage through the terminal block 16, the input end of the second incoming line voltage breaker 9 is connected with the 2# incoming line voltage through the terminal block 16, the input end of the first bus voltage breaker 10 is connected with the 1-section bus voltage through the terminal block 16, and the input end of the second bus voltage breaker 11 is connected with the 2-section bus voltage through the terminal block 16; the output end of the first incoming line voltage circuit breaker 8 is connected to the 1# incoming line voltage input end of the backup automatic switching device 5, the output end of the second incoming line voltage circuit breaker 9 is connected to the 2# incoming line voltage input end of the backup automatic switching device 5, the output end of the first bus voltage circuit breaker 10 is connected to the 1-section bus voltage input end of the backup automatic switching device 5, and the output end of the second bus voltage circuit breaker 11 is connected to the 2-section bus voltage input end of the backup automatic switching device 5; as shown in fig. 4, one end of the 1# incoming line breaker indicator light 2, the 2# incoming line breaker indicator light 3, and the sectionalized breaker indicator light 4 is connected in parallel to the positive power source end for controlling the output of the air circuit breaker 7, one normally open contact of the second intermediate relay 18 and one normally closed contact of the second intermediate relay 18 are respectively connected in series with two input ends of the 1# incoming line breaker indicator light 2, one normally open contact of the first intermediate relay 17 and one normally closed contact of the first intermediate relay 17 are respectively connected in series with two input ends of the 2# incoming line breaker indicator light 3, one normally open contact of the third intermediate relay 19 and one normally closed contact of the third intermediate relay 19 are respectively connected in series with two input ends of the sectionalized breaker indicator light 4; according to fig. 3, the auxiliary contacts of the first control switch 12, the second control switch 13, the third control switch 14 and the position selecting switch 15 are respectively connected to the switching value input end of the backup power automatic switching device 5; the outlet of the backup power automatic switching device 5 is connected to the terminal block 16. On the premise of ensuring correct wiring, a power supply air circuit breaker 6, a control air circuit breaker 7, a first incoming line voltage circuit breaker 8, a second incoming line voltage circuit breaker 9, a first bus voltage circuit breaker 10 and a second bus voltage circuit breaker 11 are positioned at a closed position, and a position selection switch 15 is rotated to a spare power automatic switching position;

as shown in fig. 2, the 1# incoming line voltage, the 1# incoming line current, the 2# incoming line voltage, the 2# incoming line current, the 1-segment bus voltage, the 2-segment bus voltage, and the segmented current are accessed to the backup power automatic switching device 5 as a basis for determining the incoming line voltage, the current, and the bus voltage; when the miniature voltage circuit breakers normally operate, the miniature voltage circuit breakers are required to be in a closing state;

as shown in fig. 3, the position of the 1# incoming line breaker, the position of the 2# incoming line breaker, the position of the sectionalized breaker, the spare power automatic switching input, the 1# incoming line protection trip, the 1# incoming line manual trip, the 1# incoming line remote control trip, the 2# incoming line protection trip, the 2# incoming line manual trip and the 2# incoming line remote control trip are connected into the spare power automatic switching device as the basis of the spare power automatic switching charging/discharging and action; when the device normally operates, the position selecting switch is rotated to the input position;

the working principle and the embodiments of the present invention are explained in detail with reference to the drawings, but the present invention is not limited to the above embodiments: and in a single-bus double-incoming-line wiring mode, the sectional judgment condition is changed into the relevant condition of the opposite incoming line. The utility model discloses with spare power automatic switching principle, experimental unanimity, furthest's reduction spare power automatic switching's principle, wiring make the student combine together with the experiment of reality when learning theoretical knowledge such as spare power automatic switching map, control principle, strengthen student's hands-on ability, the theory combines together with the practice, the training effect is showing and is improving.

Claims

1. The utility model provides a spare power automatic switching emulation teaching screen which characterized by: the front panel of the cabinet body (1) is of a detachable structure; the automatic power supply system comprises a 1# incoming line breaker indicator lamp (2), a 2# incoming line breaker indicator lamp (3), a segmented breaker indicator lamp (4), a spare power automatic switching device (5), a power supply air circuit breaker (6), a control air circuit breaker (7), a first incoming line voltage circuit breaker (8), a second incoming line voltage circuit breaker (9), a first bus voltage circuit breaker (10), a second bus voltage circuit breaker (11), a first control switch (12), a second control switch (13), a third control switch (14) and a position selecting switch (15) which are all installed on a panel of a cabinet body (1), and a terminal block (16), a first intermediate relay (17), a second intermediate relay (18) and a third intermediate relay (19) are installed inside the cabinet body (1); the connection mode of each component is as follows: the air circuit breaker comprises a 1# incoming line circuit breaker indicator lamp (2), a 2# incoming line circuit breaker indicator lamp (3) and a segmented circuit breaker indicator lamp (4), wherein one end of the 1# incoming line circuit breaker indicator lamp (2), one end of the 2# incoming line circuit breaker indicator lamp (3) is connected to a positive power source end for controlling the output of an air circuit breaker (7) in parallel, a normally open contact of a second intermediate relay (18) and a normally closed contact of the second intermediate relay (18) are respectively connected with two input ends of the 1# incoming line circuit breaker indicator lamp (2) in series, a normally open contact of a first intermediate relay (17) and a normally closed contact of the first intermediate relay (17) are respectively connected with two input ends of the 2# incoming line circuit breaker indicator lamp (3) in series, and a normally open contact of a third intermediate relay (19) and a normally closed; the power supply air circuit breaker (6) is connected with the power supply input end of the spare power automatic switching device (5); the input end of a first incoming line voltage breaker (8) is connected with a 1# incoming line voltage through a terminal row (16), the input end of a second incoming line voltage breaker (9) is connected with a 2# incoming line voltage through the terminal row (16), the input end of a first bus voltage breaker (10) is connected with a 1-section bus voltage through the terminal row (16), and the input end of a second bus voltage breaker (11) is connected with a 2-section bus voltage through the terminal row (16); the output end of a first incoming line voltage breaker (8) is connected to the No. 1 incoming line voltage input end of a spare power automatic switching device (5), the output end of a second incoming line voltage breaker (9) is connected to the No. 2 incoming line voltage input end of the spare power automatic switching device (5), the output end of a first bus voltage breaker (10) is connected to the No. 1 bus voltage input end of the spare power automatic switching device (5), and the output end of a second bus voltage breaker (11) is connected to the No. 2 bus voltage input end of the spare power automatic switching device (5); auxiliary contacts of a first control switch (12), a second control switch (13), a third control switch (14) and a position selecting switch (15) are respectively connected to a switching value input end of the spare power automatic switching device (5); the outlet of the spare power automatic switching device (5) is connected to the terminal block (16).