New energy European style box transformer substation circuit

Abstract

The utility model belongs to the technical field of electrical control, and provides a new energy European box transformer substation circuit which comprises a main transformer, the high-voltage side of the main transformer is connected with a high-voltage line, the low-voltage side of the main transformer is connected with a low-voltage line, and the low-voltage side of the main transformer is further connected with a cooling line. The cooling circuit comprises a knife fuse switch, an auxiliary transformer, a first miniature circuit breaker, a second miniature circuit breaker, a third miniature circuit breaker, a transformer body heat dissipation fan and a transformer chamber grading starting heat dissipation fan, and the first miniature circuit breaker is provided with an under-voltage release accessory; and the first miniature circuit breaker is connected with a frame circuit breaker secondary control loop of a low-voltage line through an under-voltage release auxiliary contact. According to the utility model, the phenomenon that the main transformer runs at high temperature and is burnt out due to the loss of a working power supply of the heat dissipation fan because the overall damage of the box transformer or the loss of an auxiliary secondary power supply in the box transformer caused by the burning and fault of the auxiliary transformer can be reduced or prevented.

Description

TECHNICAL FIELD

[0001] The utility model belongs to electrical control technical field, specifically, relate to a new energy European style box transformer circuit. BACKGROUND

[0002] The main transformer of the new energy European transformer is a dry-type transformer, and the capacity of the main transformer is generally 630kVA~5500kVA or above. During the operation of the new energy European transformer, the temperature of the main transformer is increased due to the influence of outdoor temperature change or overloading operation. The cooling measures for the main transformer include natural air cooling and forced air cooling. The large-capacity main transformer adopts forced air cooling, that is, the transformer body is equipped with a cooling fan, and the cooling fan is started in stages to cool the transformer. An auxiliary transformer is arranged in the box transformer to supply power to the auxiliary secondary circuit in the box transformer, and the power supply of the cooling fan is taken from the small-capacity auxiliary transformer in the box transformer.

[0003] In summary, the transformer of the new energy European transformer is cooled by forced air cooling through the cooling fan. If the small-capacity auxiliary transformer is burned out or fails to provide power to the cooling fan when the main transformer is operated at high temperature, the cooling fan does not operate, and the main transformer continues to operate at high temperature and is burned out. At the same time, the failure or burning of the auxiliary transformer body can also cause damage to the entire box transformer. UTILITY MODEL CONTENT

[0004] To solve the problems in the prior art, the utility model provides a new energy European style box transformer circuit, which reduces or prevents the overall damage of the box transformer caused by the burning and failure of the auxiliary transformer, or causes the loss of auxiliary secondary power in the box transformer, so that the working power supply of the cooling fan is lost, and then the phenomenon of high-temperature operation and burning of the main transformer of the new energy European transformer occurs, thereby improving the stable and safe operation of the new energy European transformer.

[0005] The utility model adopts the following technical solutions.

[0006] A new energy European style box transformer circuit, comprising a main transformer, a high-voltage side of the main transformer being connected with a high-voltage line, a low-voltage side of the main transformer being connected with a low-voltage line, and the low-voltage side of the main transformer being further connected with a cooling line; the cooling line comprises a knife-fuse switch, an auxiliary transformer, a first miniature circuit breaker, a second miniature circuit breaker, a third miniature circuit breaker, a transformer body cooling fan, and a transformer room step-starting cooling fan, the low-voltage side of the main transformer is connected with the high-voltage side of the auxiliary transformer through the knife-fuse switch, the low-voltage side of the auxiliary transformer is connected with one end of the first miniature circuit breaker, the other end of the first miniature circuit breaker is connected with the transformer body cooling fan through the second miniature circuit breaker, and the other end of the first miniature circuit breaker is further connected with the transformer room step-starting cooling fan through the third miniature circuit breaker;

[0007] The first miniature circuit breaker is configured with an under-voltage release accessory, and the first miniature circuit breaker is connected with the frame circuit breaker of the low-voltage line through an under-voltage release auxiliary contact to form an auxiliary transformer under-voltage tripping frame circuit breaker loop.

[0008] Further, in the auxiliary transformer under-voltage tripping frame circuit breaker loop, the L terminal of the auxiliary transformer low-voltage side stable power supply is connected with the D1 terminal of the first miniature circuit breaker, the D2 terminal of the first miniature circuit breaker is connected with one end of the under-voltage release auxiliary contact, the other end of the under-voltage release auxiliary contact is connected with one end of the frame circuit breaker first auxiliary contact, the other end of the frame circuit breaker first auxiliary contact is connected with one end of the frame circuit breaker control unit tripping coil, the other end of the frame circuit breaker control unit tripping coil is connected with the D3 terminal of the first miniature circuit breaker, and the D4 terminal of the first miniature circuit breaker is connected with the N terminal of the auxiliary transformer low-voltage side switch stable power supply.

[0009] Further, the low-voltage line comprises a frame circuit breaker, a current transformer, a molded case circuit breaker, an inverter and a PLC, one end of the low-voltage side of the main transformer is connected with the frame circuit breaker, the other end of the frame circuit breaker is connected with the low-voltage side bus, the current transformer is fixed on the low-voltage side bus in a core-penetrating manner, the inverter is connected with the low-voltage side bus through the molded case circuit breaker, the PLC is connected with the low-voltage side bus through the molded case circuit breaker, one end of the surge protector is grounded, the other end of the surge protector is connected with one end of the fuse, and the other end of the fuse is connected with the low-voltage side bus.

[0010] Further, the high-voltage line comprises a high-voltage cable, a disconnector, a high-voltage fuse, a load switch and a grounding switch, one end of the high-voltage cable is connected with the disconnector, the other end of the disconnector is connected with one end of the high-voltage fuse, the other end of the high-voltage fuse is connected with one end of the load switch, the other end of the load switch is connected with one end of the grounding switch and the high-voltage side of the main transformer, and the other end of the grounding switch is grounded.

[0011] The high-voltage line further comprises a lightning rod, one end of the lightning rod is grounded, and the other end of the lightning rod is connected with the high-voltage incoming line side bus.

[0012] Further, the high-voltage line further comprises a first display assembly and a second display assembly, the first display assembly comprises a first sensor and a first live display, one end of the first sensor is connected with the disconnector, the other end of the first sensor is connected with one end of the first live display, and the other end of the first live display is grounded.

[0013] The second display assembly comprises a second sensor and a second live display, one end of the second sensor is connected with the load switch, the other end of the second sensor is connected with one end of the second live display, and the other end of the second live display is grounded.

[0014] The utility model discloses an advantageous effect lies in, compared with prior art, the utility model provides a new energy european style box transformer circuit, the low voltage side configuration under voltage release of auxiliary transformer, when auxiliary transformer burns or breakdown, when the auxiliary transformer low voltage side has no rated voltage output, or when main transformer high temperature operation, and the under voltage release of auxiliary transformer or low voltage phenomenon condition, under voltage release acts, and the main transformer low voltage side frame circuit breaker is connected and jumps, and the main transformer low voltage side load is cut off and realizes main transformer no -load operation, protects main transformer to reduce the risk of new energy european transformer continuous high temperature operation and then lead to burn down. BRIEF DESCRIPTION OF DRAWINGS

[0015] Figure 1 The utility model provides a new energy european style box transformer primary main circuit schematic diagram for the utility model,

[0016] Figure 2 The utility model provides frame circuit breaker secondary control circuit schematic diagram.

[0017] 1-main transformer;2-high voltage line;21-high voltage line;22-isolating switch;23-high voltage fuse;24-first display component;25-second display component;26-lightning rod;27-grounding switch;28-load switch;3-low voltage line;31-frame circuit breaker;32-current transformer;33-moulded case circuit breaker;34-inverter;35-PLC;36-fuse;37-surge protector;4-cooling circuit;41-knife fuse switch;42-auxiliary transformer;43-first miniature circuit breaker;44-second miniature circuit breaker;45-third miniature circuit breaker;46-transformer body cooling fan;47-transformer room graded starting cooling fan;5-frame circuit breaker control unit;51-frame circuit breaker first auxiliary contact;52-processing unit;53-frame circuit breaker second auxiliary contact;54-frame circuit breaker third auxiliary contact;55-closing coil;56-opening coil;57-energy storage motor;58-frame circuit breaker fourth auxiliary contact;6-measuring and control protection device;7-remote on-site closing and opening change-over switch;8-under voltage release auxiliary contact. DETAILED DESCRIPTION

[0018] In order to make the utility model's purpose, technical scheme and advantage more clear, below, combining the drawings in the utility model embodiment, the technical scheme of the utility model is clearly and completely described.The embodiment described in the application is only a part of the embodiment of the utility model, not all embodiments.Based on the spirit of the utility model, all other embodiments obtained by those skilled in the art without making creative labor are within the protection scope of the utility model.

[0019] As Figure 1As shown, the high-voltage side of the main transformer 1 is connected with the high-voltage line 2, the low-voltage side of the main transformer 1 is connected with the low-voltage line, and the low-voltage side of the main transformer is also connected with the cooling line. The high-voltage line 2: the 35KV high-voltage cable 21 is connected with one end of the disconnector 22, the other end of the disconnector 22 is connected with one end of the high-voltage fuse 23, the other end of the high-voltage fuse 23 is connected with one end of the load switch 28, the other end of the load switch 28 is connected with one end of the grounding switch 27 and the high-voltage side of the main transformer 1, and the other end of the grounding switch 27 is grounded. One end of the first display assembly 24 is connected with the disconnector 22, and the other end is grounded. One end of the lightning rod 26 is connected with the high-voltage incoming line side bus, and the other end is grounded. One end of the second display assembly 25 is connected with the load switch 28, and the other end is grounded. The first display assembly 24 includes a first sensor and a first live display. One end of the first sensor is connected with the disconnector 22, and the other end of the first sensor is connected with one end of the first live display. The other end of the first live display is grounded. The second display assembly 25 includes a second sensor and a second live display. One end of the second sensor is connected with the load switch 28, and the other end of the second sensor is connected with one end of the second live display. The other end of the second live display is grounded.

[0020] The low-voltage line 3: the low-voltage side of the main transformer 1 is connected with one end of the frame circuit breaker 31, the other end of the frame circuit breaker 31 is connected with the low-voltage side bus, the current transformer 32 is fixed on the low-voltage side bus in a core-penetrating manner, the inverter 34 and the PLC 35 are both connected with the low-voltage side bus through the molded case circuit breaker 33, the low-voltage side bus is connected with one end of the fuse 36, the other end of the fuse 36 is connected with one end of the surge protector 37, and the other end of the surge protector 37 is grounded, which is used for overvoltage protection.

[0021] The cooling line 4: the low-voltage side of the main transformer 1 is also connected with the high-voltage side of the auxiliary transformer 42 through the knife fuse switch 41, the low-voltage side of the auxiliary transformer 42 is connected with one end of the first miniature circuit breaker 43, the other end of the first miniature circuit breaker 43 is connected with the transformer body cooling fan 45 through the second miniature circuit breaker 44, and the other end of the first miniature circuit breaker 43 is connected with the transformer room step-starting cooling fan 47 through the third miniature circuit breaker 45.

[0022] The parameters of the main transformer 1 are 35 / 0.8kV, Dy11, the parameters of the auxiliary transformer 42 are SG11-5kVA, 0.8 / 0.4kV, Dyn11, Uk=4%, the rated voltage of the high-voltage and low-voltage sides of the auxiliary transformer 42 is 0.8 / 0.4kV, and the secondary side of the auxiliary transformer can output AC220V or AC380V working voltage.

[0023] The first miniature circuit breaker 43 of the auxiliary transformer 42 is configured with an under-voltage release to detect whether there is an under-voltage or low-voltage phenomenon on the low-voltage side of the auxiliary transformer, and to monitor the running state of the auxiliary transformer in real time.

[0024] As shown in Figure 2 Fig. 2, the secondary control circuit of the frame circuit breaker 31 includes a control power circuit, a closing indication circuit, an opening indication circuit, a local closing circuit, a local opening circuit, a remote closing circuit, a remote opening circuit, a protection tripping circuit, an auxiliary transformer under-voltage tripping frame circuit breaker circuit, an energy storage circuit, and an energy storage indication circuit.

[0025] The control power circuit: the L terminal of the low-voltage side stable power supply of the auxiliary transformer 42 is connected with the D1 terminal of the first miniature circuit breaker 43, the D2 terminal of the first miniature circuit breaker 43 is connected with one end of the processing unit 52 of the frame circuit breaker control unit 5, the other end of the processing unit 52 is connected with the D3 terminal of the first miniature circuit breaker 43, and the D4 terminal of the first miniature circuit breaker 43 is connected with the N terminal of the low-voltage side stable power supply of the auxiliary transformer 42. The processing unit is the intelligent controller of the frame circuit breaker, which has protection functions such as overload, short circuit, grounding, voltage, frequency, phase sequence, and current imbalance, measurement functions such as voltage, current, power, electric quantity, and harmonic, and networking functions such as communication and regional selectivity interlocking.

[0026] The closing indication circuit: the L terminal of the low-voltage side stable power supply of the auxiliary transformer 42 is connected with the D1 terminal of the first miniature circuit breaker 43, the D2 terminal of the first miniature circuit breaker 43 is connected with one end of the closing indication lamp HR, the other end of the closing indication lamp HR is connected with the D3 terminal of the first miniature circuit breaker 43 through the second auxiliary contact 53 of the frame circuit breaker, and the D4 terminal of the first miniature circuit breaker 43 is connected with the N terminal of the low-voltage side stable power supply of the auxiliary transformer 42. When the second auxiliary contact is closed, the closing indication lamp is lit for closing indication.

[0027] The opening indication circuit: the L terminal of the low-voltage side stable power supply of the auxiliary transformer 42 is connected with the D1 terminal of the first miniature circuit breaker 43, the D2 terminal of the first miniature circuit breaker 43 is connected with one end of the opening indication lamp HG, the other end of the opening indication lamp HG is connected with the D3 terminal of the first miniature circuit breaker 43 through the third auxiliary contact 54 of the frame circuit breaker, and the D4 terminal of the first miniature circuit breaker 43 is connected with the N terminal of the low-voltage side stable power supply of the auxiliary transformer 42. When the third auxiliary contact is closed, the opening indication lamp is lit for opening indication.

[0028] Local closing circuit: the L end of the low-voltage side stable power supply of the auxiliary transformer 42 is connected with the D1 end of the first miniature circuit breaker 43, the D2 end of the first miniature circuit breaker 43 is connected with the S1 contact of the remote local closing and opening switch 7, the S2 contact of the remote local closing and opening switch 7 is connected with one end of the closing coil 55 of the frame circuit breaker control unit 5, the other end of the closing coil 55 is connected with the D3 end of the first miniature circuit breaker 43, the D4 end of the first miniature circuit breaker 43 is connected with the N end of the low-voltage side stable power supply of the auxiliary transformer. When the S1 contact and the S2 contact of the remote local closing and opening switch 7 are connected, the local closing of the frame circuit breaker 31 is realized.

[0029] Local opening circuit: the L end of the low-voltage side stable power supply of the auxiliary transformer 42 is connected with the D1 end of the first miniature circuit breaker 43, the D2 end of the first miniature circuit breaker 43 is connected with the S3 contact of the remote local closing and opening switch 7, the S4 contact of the remote local closing and opening switch 7 is connected with one end of the opening coil 56 of the frame circuit breaker control unit 5, the other end of the opening coil 56 of the frame circuit breaker control unit 5 is connected with the D3 end of the first miniature circuit breaker 43, the D4 end of the first miniature circuit breaker 43 is connected with the N end of the low-voltage side stable power supply of the auxiliary transformer 42. When the S3 contact and the S4 contact of the remote local closing and opening switch 7 are connected, the local opening of the frame circuit breaker 31 is realized.

[0030] Remote closing circuit: the L end of the low-voltage side stable power supply of the auxiliary transformer 42 is connected with the D1 end of the first miniature circuit breaker 43, the D2 end of the first miniature circuit breaker 43 is connected with the S5 contact of the remote local closing and opening switch 7, the S6 contact of the remote local closing and opening switch 7 is connected with the B1 contact of the measurement and control protection device 6, the B2 contact of the measurement and control protection device 6 is connected with one end of the closing coil 55 of the frame circuit breaker control unit 5, the other end of the closing coil 55 of the frame circuit breaker control unit 5 is connected with the D3 end of the first miniature circuit breaker 43, the D4 end of the first miniature circuit breaker 43 is connected with the N end of the low-voltage side stable power supply of the auxiliary transformer 42. When the S5 contact and the S6 contact of the remote local closing and opening switch 7 are connected, and the B1 contact and the B2 contact of the measurement and control protection device 6 are connected, the remote closing of the frame circuit breaker 31 is realized.

[0031] Remote control opening circuit: the L end of the low-voltage side stable power supply of the auxiliary transformer 42 is connected with the D1 end of the first miniature circuit breaker 43, the D2 end of the first miniature circuit breaker 43 is connected with the S5 contact of the remote and on-site closing and opening switch 7, the S6 contact of the remote and on-site closing and opening switch 7 is connected with the B1 contact of the measurement and control protection device 6, the B3 contact of the measurement and control protection device 6 is connected with one end of the opening coil 56 of the frame circuit breaker control unit 5, the other end of the opening coil 56 of the frame circuit breaker control unit 5 is connected with the D3 end of the first miniature circuit breaker 43, the D4 end of the first miniature circuit breaker 43 is connected with the N end of the low-voltage side stable power supply of the auxiliary transformer 42, when the S5 contact and the S6 contact of the remote and on-site closing and opening switch 7 are connected, and the B1 contact and the B3 contact of the measurement and control protection device 6 are connected, the remote control opening of the frame circuit breaker 31 is realized.

[0032] Protection tripping circuit: the L end of the low-voltage side stable power supply of the auxiliary transformer 42 is connected with the D1 end of the first miniature circuit breaker 43, the D2 end of the first miniature circuit breaker 43 is connected with the B4 contact of the measurement and control protection device 6, the B5 contact of the measurement and control protection device 6 is connected with one end of the opening coil 56 of the frame circuit breaker control unit 5, the other end of the opening coil 56 of the frame circuit breaker control unit 5 is connected with the D3 end of the first miniature circuit breaker 43, the D4 end of the first miniature circuit breaker 43 is connected with the N end of the low-voltage side stable power supply of the auxiliary transformer 42, when the B4 contact and the B5 contact of the measurement and control protection device 6 are connected, the frame circuit breaker 31 is opened to cut off the faulty equipment or line, and the safe operation of the system is protected.

[0033] Auxiliary transformer under-voltage tripping frame circuit breaker circuit: the L end of the low-voltage side stable power supply of the auxiliary transformer 42 is connected with the D1 end of the first miniature circuit breaker 43, the D2 end of the first miniature circuit breaker 43 is connected with one end of the auxiliary contact 8 of the under-voltage release, the other end of the auxiliary contact 8 of the under-voltage release is connected with one end of the first auxiliary contact 51 of the frame circuit breaker, the other end of the first auxiliary contact 51 of the frame circuit breaker is connected with one end of the opening coil 56 of the frame circuit breaker control unit 5, the other end of the opening coil 56 of the frame circuit breaker control unit 5 is connected with the D3 end of the first miniature circuit breaker 43, the D4 end of the first miniature circuit breaker 43 is connected with the N end of the low-voltage side stable power supply of the auxiliary transformer 42, when the frame circuit breaker 31 is closed and operated, the under-voltage release detects that the voltage of the low-voltage side of the auxiliary transformer 42 is 0V or the working voltage is 161±5%, the under-voltage release acts, and thus the auxiliary contact 8 of the under-voltage release acts, the auxiliary transformer under-voltage tripping frame circuit breaker circuit is connected, the opening coil 56 of the frame circuit breaker acts to make the frame circuit breaker 31 open, and the frame circuit breaker opening can cut off the access of the low-voltage side load or power supply of the main transformer, the no-load operation of the main transformer is realized by cutting off the input of the low-voltage load or power supply of the main transformer, and thus the main transformer is protected.

[0034] The L end of the low-voltage side stable power supply of the auxiliary transformer 42 is connected with the D1 end of the first miniature circuit breaker 43, the D2 end of the first miniature circuit breaker 43 is connected with one end of the energy storage motor 57 of the frame circuit breaker control unit 5, the other end of the energy storage motor 57 is connected with the D3 end of the first miniature circuit breaker 43, and the D4 end of the first miniature circuit breaker 43 is connected with the N end of the low-voltage side stable power supply of the auxiliary transformer 42.

[0035] The L end of the low-voltage side stable power supply of the auxiliary transformer 42 is connected with the D1 end of the first miniature circuit breaker 43, the D2 end of the first miniature circuit breaker 43 is connected with one end of the energy storage motor 57 of the frame circuit breaker control unit 5, the other end of the energy storage motor 57 is connected with the D3 end of the first miniature circuit breaker 43, and the D4 end of the first miniature circuit breaker 43 is connected with the N end of the low-voltage side stable power supply of the auxiliary transformer 42.

[0036] Further, the model of the first miniature circuit breaker is 63 / 3P In=20A, and the model of the second miniature circuit breaker and the third miniature circuit breaker is 63 / 2P C16A.

[0037] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present application, but not to limit it. Although the present application has been described in detail with reference to the above embodiments, those skilled in the art should understand that the specific embodiments of the present application can be modified or replaced, and any modification or replacement without departing from the spirit and scope of the present application should be covered within the protection scope of the claims of the present application.

Claims

1. A new energy European box transformer circuit, comprising a main transformer, characterized in that: the high-voltage side of the main transformer is connected with a high-voltage line, the low-voltage side of the main transformer is connected with a low-voltage line, and the low-voltage side of the main transformer is further connected with a cooling line; the cooling line comprises a knife-fusion switch, an auxiliary transformer, a first miniature circuit breaker, a second miniature circuit breaker, a third miniature circuit breaker, a transformer body cooling fan and a transformer room staged starting cooling fan, the low-voltage side of the main transformer is connected with the high-voltage side of the auxiliary transformer through the knife-fusion switch, the low-voltage side of the auxiliary transformer is connected with one end of the first miniature circuit breaker, the other end of the first miniature circuit breaker is connected with the transformer body cooling fan through the second miniature circuit breaker, and the other end of the first miniature circuit breaker is further connected with the transformer room staged starting cooling fan through the third miniature circuit breaker; the first miniature circuit breaker is provided with an under-voltage release accessory, and the first miniature circuit breaker is connected with a frame circuit breaker secondary control loop of the low-voltage line through an under-voltage release auxiliary contact, thereby forming an auxiliary transformer under-voltage tripping frame circuit breaker loop.

2. The new energy European box transformer circuit according to claim 1, characterized in that: in the auxiliary transformer under-voltage tripping frame circuit breaker loop, an L end of an auxiliary transformer low-voltage side stable power supply is connected with a D1 end of the first miniature circuit breaker, a D2 end of the first miniature circuit breaker is connected with one end of the under-voltage release auxiliary contact, the other end of the under-voltage release auxiliary contact is connected with one end of a frame circuit breaker first auxiliary contact, the other end of the frame circuit breaker first auxiliary contact is connected with one end of a frame circuit breaker control unit tripping coil, the other end of the frame circuit breaker control unit tripping coil is connected with a D3 end of the first miniature circuit breaker, and a D4 end of the first miniature circuit breaker is connected with an N end of an auxiliary transformer low-voltage side switch stable power supply.

3. The new energy European box transformer circuit according to claim 1, characterized in that: the low-voltage line comprises a frame circuit breaker, a current transformer, a molded case circuit breaker, an inverter and a PLC, the low-voltage side of the main transformer is connected with one end of the frame circuit breaker, the other end of the frame circuit breaker is connected with a low-voltage side busbar, the current transformer is fixed on the low-voltage side busbar in a core-penetrating mode, the inverter is connected with the low-voltage side busbar through the molded case circuit breaker, the PLC is connected with the low-voltage side busbar through the molded case circuit breaker, one end of a surge protector is grounded, the other end of the surge protector is connected with one end of a fuse, and the other end of the fuse is connected with the low-voltage side busbar.

4. The new energy European box transformer circuit according to claim 1, characterized in that: the high-voltage line comprises a high-voltage cable, a disconnector, a high-voltage fuse, a load switch and a grounding switch, the high-voltage cable is connected with one end of the disconnector, the other end of the disconnector is connected with one end of the high-voltage fuse, the other end of the high-voltage fuse is connected with one end of the load switch, the other end of the load switch is connected with one end of the grounding switch and the high-voltage side of the main transformer, and the other end of the grounding switch is grounded; the high-voltage line further comprises a lightning rod, one end of the lightning rod is grounded, and the other end of the lightning rod is connected with a high-voltage incoming line side busbar.

5. The new energy European box transformer circuit according to claim 4, characterized in that: ​ The high-voltage line further comprises a first display assembly and a second display assembly, the first display assembly comprises a first sensor and a first live display, one end of the first sensor is connected with the disconnecting switch, the other end of the first sensor is connected with one end of the first live display, and the other end of the first live display is grounded; The second display assembly comprises a second sensor and a second live display, one end of the second sensor is connected with the load switch, the other end of the second sensor is connected with one end of the second live display, and the other end of the second live display is grounded.

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