Fan control circuit and control system for power transformation and distribution room of chemical enterprise

Abstract

The utility model relates to a fan control circuit and a fan control system for a power transformation and distribution room of a chemical enterprise. The circuit comprises a state switch, a power supply input end, and a box surface local control module, a first signal holding module, a signal control module, an indoor control module, an outdoor control module, a second signal holding module, an isolation transformer and a combustible gas alarm controller linkage module which are sequentially connected with the power supply input end, and the temperature controller linkage module, the remote manual control module, the box surface local control module and the signal control module are electrically connected with the state switch respectively. Compared with the prior art, the device has the advantages that the fan in the power transformation and distribution room of the chemical enterprise can be accurately monitored in real time, timely heat dissipation of the power transformation and distribution room of the chemical enterprise is realized, explosive gas invasion is avoided, and safe ventilation after disasters is ensured.

Description

Technical Field

[0001] This utility model relates to the field of electrical technology, and in particular to a fan control circuit and control system for a power distribution room in a chemical enterprise. Background Technology

[0002] Chemical plants require large amounts of electricity for their production equipment, making substations a crucial component for power transmission, distribution, and control. Problems in substations can lead to the shutdown of the entire chemical production line, severely impacting production efficiency and output. Therefore, the normal operation of substations is vital for the safe operation of chemical production.

[0003] To ensure the safe operation of chemical production, chemical enterprises need to strengthen the management and maintenance of their power distribution rooms to ensure their normal operation. For chemical enterprises, the maintenance environment of power distribution rooms is more complex, requiring consideration of the following: Electrical equipment such as power cables, switches, and transformers in power distribution rooms generate a large amount of heat during operation. If not dissipated in time, this heat will accumulate in the room, causing the ambient temperature to rise. High-temperature environments not only increase the operating burden on equipment but may also trigger equipment failures or accidents. Simultaneously, chemical enterprises often involve explosive gases, and highly volatile liquids may be released in large quantities and spread up to 30 meters. When explosive gases enter the power distribution room and accumulate for a long time to reach the lower explosive limit, if there are sparks, arcs, or high temperatures in the power distribution room sufficient to ignite the explosive gas mixture, an explosion will occur, causing significant personal injury and economic losses. Furthermore, after a fire or other accident, the power distribution room may contain exhaust gases containing toxic and harmful substances, which will endanger the health of rescue or maintenance personnel.

[0004] A search revealed Chinese patent CN209100319U, which discloses a fire-fighting fan control circuit and a fire-fighting fan system. The fire-fighting fan control circuit includes a power monitoring circuit, a first control circuit on / off control circuit, a second control circuit on / off control circuit, and a main circuit on / off control circuit. This circuit monitors the main power supply circuit of the fire-fighting fan and its own power status, reporting the monitored signals to a fire alarm system connected to the control circuit during operation. However, this solution only monitors temperature in real time for timely fire alarms, without considering emergency ventilation or post-disaster exhaust. Therefore, how to achieve real-time and accurate monitoring of indoor fans in chemical plant power distribution rooms to ensure the safe operation of chemical production and effectively avoid health hazards to rescue or maintenance personnel remains a problem that needs to be solved in this field. Utility Model Content

[0005] The purpose of this utility model is to overcome the defects of the existing technology and provide a control circuit and control system for the fans in the power distribution room of a chemical enterprise. This system can monitor the fans in the power distribution room of a chemical enterprise in real time and accurately, so as to achieve timely heat dissipation in the power distribution room of the chemical enterprise, prevent the intrusion of explosive gases and ensure safe ventilation after disasters, thereby ensuring the safe operation of chemical production and effectively avoiding health hazards to rescue or maintenance personnel.

[0006] The objective of this utility model can be achieved through the following technical solutions:

[0007] According to a first aspect of this utility model, a fan control circuit for a power distribution room in a chemical enterprise is provided, comprising a status switch, a power input terminal, and a box-side local control module, a first signal holding module, a signal control module, an indoor control module, an outdoor control module, a second signal holding module, an isolation transformer, a combustible gas alarm controller linkage module, a temperature controller linkage module, and a remote manual control module connected in sequence to the power input terminal. The box-side local control module and the signal control module are also electrically connected to the status switch.

[0008] As a preferred technical solution, the control circuit further includes a protection module, which is connected between the power input terminal and the local control module on the enclosure surface.

[0009] As a preferred technical solution, the control circuit further includes a control power display module, an overload indicator module, a running signal indicator module, and a stop signal indicator module. The control power display module is connected between the power input terminal and the overload indicator module. The overload indicator module is connected between the control power display module and the local control module on the enclosure surface. The running signal indicator module is connected between the second signal holding module and the stop signal indicator module. The stop signal indicator module is connected between the running signal indicator module and the isolation transformer.

[0010] As a preferred technical solution, the control power display module, the overload indicator module, the running signal indicator module, and the stop signal indicator module each include a corresponding indicator light, and the two ends of the indicator light are respectively connected to an external three-phase power supply through the power input terminal.

[0011] As a preferred technical solution, the local control module on the enclosure surface includes at least a first switch, a first stop button, a first start button, a first thermal relay, and a first contactor connected in series. The first signal holding module includes a second contactor, which is connected in parallel across the first start button. The other end of the first switch and the other end of the first contactor are respectively connected to an external three-phase power supply through the power input terminal. The first switch is also electrically connected to the status switch.

[0012] As a preferred technical solution, the signal control module includes at least a second switch and a first intermediate relay connected in series. The other end of the second switch is connected to an external three-phase power supply through the power input terminal. The other end of the first intermediate relay is connected between the first start button and the first thermal relay. The second switch is also electrically connected to the status switch. The indoor control module includes at least a second stop button, a second start button, a third stop button, and a second intermediate relay connected in series. The other end of the second stop button is connected between the second switch and the first intermediate relay. The second intermediate relay is connected to an external three-phase power supply through the power input terminal. The outdoor control module includes at least a third start button. The second signal holding module includes at least a third intermediate relay and a fourth intermediate relay connected in parallel. The third start button is connected in parallel across the two ends of the second start button, and the third intermediate relay is connected in parallel across the two ends of the third start button.

[0013] As a preferred technical solution, the combustible gas alarm controller linkage module includes at least a combustible gas alarm controller linkage contact and a fifth intermediate relay connected in series, with the other end of the combustible gas alarm controller linkage contact and the other end of the fifth intermediate relay respectively connected to the secondary side of the isolation transformer.

[0014] As a preferred technical solution, the temperature controller linkage module includes at least a temperature controller linkage contact, which is connected in parallel to both ends of the combustible gas alarm controller linkage contact.

[0015] As a preferred technical solution, the remote manual control module includes at least a remote manual start contact, which is connected in parallel to both ends of the temperature controller linkage contact.

[0016] According to a second aspect of this utility model, a fan control system for a chemical plant substation is provided, comprising at least a three-phase power supply, a circuit breaker, a contactor, a thermal relay, and a fan control circuit for the chemical plant substation, all electrically connected; the live wires of the three-phase power supply are connected to the fan in sequence through the circuit breaker, the contactor, and the thermal relay; the fan is also connected to the grounding wire of the three-phase power supply; and the neutral wire and one of the live wires of the three-phase power supply are respectively connected to the power input terminal of the fan control circuit for the chemical plant substation.

[0017] Compared with the prior art, the present invention has the following beneficial effects:

[0018] 1. This utility model integrates a local control module on the box surface, an indoor control module, an outdoor control module, a combustible gas alarm controller linkage module, a temperature controller linkage module, and a remote manual control module into the fan control circuit. By connecting to the status switch and the power input terminal, the fan can achieve the following functions through joint control with other modules when the status switch is in different states: manual start on site (including manual start on the distribution box surface, manual start on the indoor operation switch, and manual start on the outdoor operation switch), linkage start of the automatic control system (linkage start of the temperature controller and linkage start of the combustible gas alarm controller), and remote manual start from the control room. This completes the real-time and accurate monitoring of indoor fans in chemical enterprises' power distribution systems, enabling indoor fans in power distribution systems to achieve heat dissipation, emergency ventilation, and post-disaster exhaust functions, making the functions more diverse, while reducing the number of electrical equipment and facilitating the management and maintenance of chemical enterprises.

[0019] 2. In this utility model, the indoor fan of the power distribution unit can realize multiple operation functions. Operators can operate it indoors and outdoors on site, or remotely from the control room. The combination of control room and on-site operation makes the operation of the fan more flexible and convenient.

[0020] 3. In the control system provided by this utility model, the fan adopts a dual-circuit power supply to ensure normal operation even when the main circuit fails, thus ensuring the safety of the substation and operation and maintenance personnel. Attached Figure Description

[0021] Figure 1 A schematic diagram of a fan control system provided in an embodiment of this utility model;

[0022] Figure 2 A schematic diagram of the module structure of a fan control circuit provided for an embodiment of this utility model;

[0023] Figure 3 A schematic diagram of a fan control circuit provided for an embodiment of this utility model;

[0024] Figure 4 for Figure 3 A partial enlarged view of the power input terminal 201 to the second signal holding module 210;

[0025] Figure 5 for Figure 3 A partial enlarged view of the operation signal indication module 211 to the remote manual control module 216;

[0026] Figure 6 A functional diagram of the fan control system provided in this embodiment of the utility model;

[0027] The components are as follows: 101. Three-phase power supply; 102. Circuit breaker; 103. Contactor; 104. Thermal relay; 105. Fan; 201. Power input terminal; 202. Protection module; 203. Control power display module; 204. Overload indicator module; 205. Local control module on the enclosure; 206. First signal holding module; 207. Signal control module; 208. Indoor control module; 209. Outdoor control module; 210. Second signal holding module; 211. Running signal indicator module; 212. Stop signal indicator module; 213. Isolation transformer; 214. Combustible gas alarm controller linkage module; 215. Temperature controller linkage module; 216. Remote manual control module. Detailed Implementation

[0028] The technical solutions of the present utility model will be clearly and completely described below with reference to the accompanying drawings of the embodiments. Obviously, the described embodiments are only some, not all, of the embodiments of the present utility model. Based on the embodiments of the present utility model, all other embodiments obtained by those skilled in the art without creative effort should fall within the protection scope of the present utility model.

[0029] In the description of this utility model, it should be noted that the terms "center," "upper," "lower," "left," "right," "vertical," "horizontal," "inner," and "outer," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings, or the orientation or positional relationship commonly used when the utility model product is in use. They are only for the convenience of describing this utility model and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this utility model. For example, "horizontal" simply means that its direction is more horizontal than "vertical," and does not mean that the structure must be completely horizontal, but can be slightly tilted.

[0030] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of this application, "multiple" means two or more, unless otherwise explicitly specified.

[0031] Example:

[0032] like Figure 1 As shown, this embodiment provides a fan control system for a chemical plant's power distribution room, including a three-phase power supply 101, a circuit breaker 102, a contactor 103, a thermal relay 104, and a fan control circuit for the chemical plant's power distribution room. The live wires (L1, L2, L3) of the three-phase power supply 101 are connected to the fan 105 in sequence through the circuit breaker 102, contactor 103, and thermal relay 104. The fan 105 is also connected to the grounding wire (PE) of the three-phase power supply 101. The neutral wire (N) and one of the live wires (L3) of the three-phase power supply 101 are respectively connected to the power input terminals (L, N) of the fan control circuit for the chemical plant's power distribution room. In the figure, QA represents the circuit breaker 102, QAC represents the contactor 103, and BB represents the thermal relay 104.

[0033] In this embodiment, Figure 2 This diagram illustrates the basic module structure of a fan control circuit in a chemical plant's power distribution room. The control circuit includes a status switch, a power input terminal 201, and, sequentially connected to the power input terminal 201, a protection module 202, a control power display module 203, an overload indicator module 204, a local control module 205, a first signal holding module 206, a signal control module 207, an indoor control module 208, an outdoor control module 209, a second signal holding module 210, a running signal indicator module 211, a stop signal indicator module 212, an isolation transformer 213, a combustible gas alarm controller linkage module 214, a temperature controller linkage module 215, and a remote manual control module 216. The local control module 205 and the signal control module 207 are also electrically connected to the status switch.

[0034] Figure 3 One specific structure of the control circuit is shown. Figures 4-5This is a partial enlarged view of the circuit structure. In each diagram: FA represents a fuse; KA1~KA2 represent intermediate relays no.1~intermediate relay no.2; PGR1~PGR3 represent running indicator lights (red) no.1~running indicator lights (red) no.3; PGG1~PGG3 represent stop indicator lights (green) no.1~stop indicator lights (green) no.3; PGY represents a fault indicator light (yellow); PGW represents a power indicator light (white); SF1~SF3 represent start buttons no.1~no.3; SS1~SS3 represent stop buttons no.1~no.3; SAC represents a manual rotary switch (i.e., a status switch); QAC represents a contactor; BB represents a thermal relay; TC represents an isolation transformer; K1 represents a combustible gas alarm controller linkage contact; K2 represents a temperature controller linkage contact; K3 represents a remote manual start contact in the control room; KA2(13,14) represents a group of contacts numbered 13 and 14 of intermediate relay no.2, and the remaining numbering is similar.

[0035] like Figure 4 As shown, the power input terminals 201 (L, N) are connected to the live wire and neutral wire N of the three-phase power supply 101 of the control system, respectively, providing input power (220V AC) for the entire control circuit. Optionally, the protection module 202 uses a fuse FA, with one end of the fuse FA connected to the live wire and the other end connected to the primary side of the isolation transformer 213. The control power display module 203 includes a PGW, with one end of the PGW connected to the fuse FA (terminal 2 of FA in the figure) and the other end connected to the N terminal of the power input terminal 201; the overload indication module 204 includes a thermal relay BB (97, 98) and a PGY connected in series, with the other end of BB (97, 98) connected to the fuse FA (terminal 2 of FA in the figure) and the other end of PGY connected to the N terminal of the power input terminal 201.

[0036] The local control module 205 includes a first switch, SS1 (11, 12) (i.e., the first stop button), SF1 (13, 14) (i.e., the first start button), BB (95, 96) (i.e., the first thermal relay), and QAC (A1, A2) (i.e., the first contactor) connected in series. The first signal holding module 206 includes QAC (13, 14) (i.e., the second contactor). QAC (13, 14) is connected in parallel across SF1 (13, 14). The other end of the first switch (end 1 in the figure) is connected to the live wire of the external three-phase power supply 101 through the fuse FA and the power input terminal 201. The other end of QAC (A1, A2) is connected to the neutral wire N of the external three-phase power supply 101 through the power input terminal 201. The first switch is also electrically connected to SAC.

[0037] The signal control module 207 includes a second switch and KA1 (13, 14) (i.e., the first intermediate relay) connected in series. The other end of the second switch (terminal 3 in the figure) is connected to the live wire of the external three-phase power supply 101 through the fuse FA and the power input terminal 201. The other end of KA1 (13, 14) is connected between SF1 (13, 14) and BB (95, 96). The second switch is also electrically connected to SAC.

[0038] The indoor control module 208 includes SS2 (11, 12) (i.e., the second stop button), SF2 (13, 14) (i.e., the second start button), SS3 (11, 12) (i.e., the third stop button) and KA1 (A1, A2) (i.e., the second intermediate relay) connected in series. The other end of SS2 (11, 12) is connected between the second switch and KA1 (13, 14). KA1 (A1, A2) is connected to the neutral line N of the external three-phase power supply 101 through the power input terminal 201.

[0039] The outdoor control module 209 includes SF3(13, 14) (i.e., the third start button), and the second signal holding module 210 includes KA1(23, 24) (i.e., the third intermediate relay) and KA2(13, 14) (i.e., the fourth intermediate relay) connected in parallel. SF3(13, 14) is connected in parallel across the two ends of SF2(13, 14), and KA1(23, 24) is connected in parallel across the two ends of SF3(13, 14).

[0040] like Figure 5 As shown, the operation signal indication module 211 includes QAC (23, 24) and PGR1, PGR2, and PGR3. QAC (23, 24) is connected in series with PGR1, and the other end of QAC (23, 24) is connected to the live wire of the external three-phase power supply 101 through the fuse FA and the power input terminal 201. The other end of PGR1 is connected to the neutral wire N of the external three-phase power supply 101 through the power input terminal 201. In addition, PGR2 is connected in parallel across the two ends of PGR1, and PGR3 is connected in parallel across the two ends of PGR2.

[0041] The stop signal indication module 212 includes QAC(11, 12) and PGG1, PGG2, and PGG3. QAC(11, 12) is connected in series with PGG1, and the other end of QAC(11, 12) is connected to the live wire of the external three-phase power supply 101 through the fuse FA and the power input terminal 201. The other end of PGG1 is connected to the neutral wire N of the external three-phase power supply 101 through the power input terminal 201. In addition, PGG2 is connected in parallel across the two ends of PGG1, and PGG3 is connected in parallel across the two ends of PGG2.

[0042] The combustible gas alarm controller linkage module 214 includes K1 (i.e., combustible gas alarm controller linkage contact) and KA2 (A1, A2) (i.e., the fifth intermediate relay) connected in series. The other end of K1 and the other end of KA2 (A1, A2) are respectively connected to the secondary side of the isolation transformer 213. The temperature controller linkage module 215 includes K2 (i.e., temperature controller linkage contact), which is connected in parallel to both ends of K1. The remote manual control module 216 includes K3 (i.e., remote manual start contact), which is connected in parallel to both ends of K2.

[0043] Figure 3 and Figure 4 The SAC in this diagram refers to the state switch. As shown in the figure, the SAC has three states, used to control the state of the entire control circuit. Therefore, depending on the different states of the SAC, the fan control system provided in this embodiment can achieve the following: Figure 6 The three types of fan control methods shown are on-site manual start, automatic control system linkage start, and remote manual start from the control room. On-site manual start includes manual start from the distribution box, manual start from the indoor operating switch, and manual start from the outdoor operating switch. Automatic control system linkage start includes linkage start from the temperature controller and linkage start from the combustible gas alarm controller.

[0044] In practical applications, a multi-functional fan can be installed in the power distribution room of a chemical plant, using the aforementioned control system and circuitry to meet the control requirements for heat dissipation, explosive gas intrusion, and post-disaster safe ventilation in the power distribution room. Specifically:

[0045] A temperature controller is installed in the power distribution room. This controller consists of a temperature sensor, control circuit, and actuator. It monitors the ambient temperature in real time and makes judgments based on preset temperature thresholds. Once the ambient temperature exceeds the set range, the temperature controller activates the cooling fan, causing airflow to expel hot air from the power distribution room and introduce fresh outdoor air. This not only lowers the indoor temperature, maintaining a suitable operating environment in the power distribution room, but also prevents safety hazards caused by equipment overheating, ensures that electrical equipment operates at a suitable temperature, extends equipment lifespan, and guarantees normal equipment operation and stable power system operation.

[0046] Flammable gas detectors are installed at the fan inlet of the power distribution room, at the opening facing Class A workshops, or in places prone to gas accumulation such as cable trenches. When the concentration detected by the sensor in the flammable gas detector reaches the set value, the signal is fed back to the flammable gas alarm controller in the control room. The flammable gas alarm controller then activates the emergency exhaust fan to promptly reduce the concentration of flammable gas in the power distribution room and prompts relevant maintenance personnel to immediately inspect the release source, check the relevant equipment, and take corresponding measures to prevent release and protect personnel.

[0047] After a fire or other accident has ended, control room operators can remotely or on-site rescue and maintenance personnel can activate the post-disaster ventilation fans in the substation from the outside. The fans will reduce the indoor smoke concentration, improve visibility, and remove exhaust gases and gases containing toxic and harmful substances from the substation, thus protecting the health of maintenance personnel.

[0048] Based on the aforementioned substation setup, the operation process of the fan control circuit provided in this embodiment is as follows:

[0049] Under normal circumstances, circuit breaker 102 is closed.

[0050] When SAC is in state 1, the fan can be manually started and stopped on the indoor and outdoor switches on site, remotely started manually from the control room, started in conjunction with the combustible gas alarm controller, and started in conjunction with the temperature controller.

[0051] 1) Manually press the start buttons SF2-SF3 (SF2 is the indoor switch, SF3 is the outdoor switch). The fan is ready to start, intermediate relay KA1 is energized, the normally open contacts of KA1(13,14) and KA1(23,24) close, contactor QAC is energized, and the fan starts. The normally open contacts of QAC(13,14) and QAC(23,24) close, and the fan starts. The PGR1-PGR3 (fan) running indicator lights are energized and illuminated. Manually pressing the start buttons SF1-SF2 de-energizes intermediate relay KA1 and contactor QAC, the fan stops, and the PGG1-PGG3 (fan) stop indicator lights are energized and illuminated.

[0052] 2) When the combustible gas alarm controller is activated, the normally open contacts of K1 (13, 14) close; or when the temperature controller is activated, the normally open contacts of K2 (13, 14) close; or when remotely manually activated, the normally open contacts of K3 (13, 14) close, intermediate relay KA2 is energized, the normally open contacts of KA2 (13, 14) close, intermediate relay KA1 is energized, the normally open contacts of KA1 (13, 14) and KA1 (23, 24) close, contactor QAC is energized, the normally open contacts of QAC (13, 14) and QAC (23, 24) close, the fan starts, and the PGR1~PGR3 (fan) running indicator lights illuminate. When the combustible gas alarm controller, temperature controller, or remote manually activated mode is not in the activated state, intermediate relays KA1~KA2 and contactor QAC are de-energized, the fan stops, and the PGG1~PGG3 (fan) stop indicator lights illuminate.

[0053] When the circuit breaker is closed, the fan is powered on, and the PGW power indicator (white) lights up. When the thermal relay is activated, the normally open contact of BB (97, 98) closes, the PGY fault indicator (yellow) lights up, the normally closed contact of BB (95, 96) opens, the contactor QAC is de-energized, the fan stops, and the PGG1~PGG3 (fan) stop indicator lights are energized and lit up.

[0054] When SAC is in state 2, the wind turbine is under maintenance and cannot be started or stopped, in order to ensure the safety of on-site maintenance personnel.

[0055] When SAC is in state 3, the fan can be manually started and stopped from the distribution box. Manually pressing the start button SF1 (SF1 is the switch on the distribution box) puts the fan in the start-ready state, energizes contactor QAC, closes the normally open contacts of QAC(13, 14) and QAC(23, 24), starts the fan, and illuminates the PGR1~PGR3 (fan) operation indicator lights. PGR1 is the indicator light on the distribution box, PGR2 is the indicator light on the indoor switch, and PGR3 is the indicator light on the outdoor switch. Manually pressing the start button SS1 de-energizes contactor QAC, stops the fan, and illuminates the PGG1~PGG3 (fan) stop indicator lights.

[0056] In summary, this application can meet the requirements of manual start and stop of the fan on the indoor and outdoor switches on site, remote manual start in the control room, linkage start with the combustible gas alarm controller, linkage start with the temperature controller, and manual start and stop on the distribution box.

[0057] In the context of this invention, components such as circuit breakers, contactors, thermal relays, fuses, intermediate relays, indicator lights, time relays, and manual rotary switches can all be commercially available products. For example, circuit breaker 102 can be any specific model from the NSX series, contactor can be any specific model from the CK3 series, thermal relay can be any specific model from the CJR3 series, and intermediate relay can be any specific model from the N22E series. Furthermore, the fan can be an explosion-proof device, and corrosion-resistant and high-temperature-resistant materials can be selected to cope with the complex post-disaster environment of the substation.

[0058] The preferred embodiments of this utility model have been described in detail above. It should be understood that those skilled in the art can make numerous modifications and variations based on the concept of this utility model without creative effort. Therefore, all technical solutions that can be obtained by those skilled in the art based on the concept of this utility model through logical analysis, reasoning, or limited experimentation on the basis of existing technology should be within the scope of protection defined by the claims.

Claims

1. A fan control circuit for a chemical plant transformer substation, characterized by, The control circuit comprises a state switch, a power input end, and a cabinet face local control module, a first signal holding module, a signal control module, an indoor control module, an outdoor control module, a second signal holding module, an isolation transformer, a combustible gas alarm controller linkage module, a temperature controller linkage module and a remote manual control module connected in sequence with the power input end, and the cabinet face local control module and the signal control module are also electrically connected with the state switch.

2. The chemical industry variable power distribution room fan control circuit according to claim 1, characterized in that, The control circuit further comprises a protection module connected between the power input end and the cabinet face local control module.

3. The chemical industry variable power distribution room fan control circuit according to claim 1, characterized in that, The control circuit further comprises a control power display module, an overload indication module, a running signal indication module and a stop signal indication module, the control power display module is connected between the power input end and the overload indication module, the overload indication module is connected between the control power display module and the cabinet face local control module, the running signal indication module is connected between the second signal holding module and the stop signal indication module, and the stop signal indication module is connected between the running signal indication module and the isolation transformer.

4. The chemical industry variable power distribution room fan control circuit according to claim 3, characterized in that, The control power display module, the overload indication module, the running signal indication module and the stop signal indication module each comprise a corresponding indicator lamp, and the two ends of the indicator lamp are connected to an external three-phase power supply through the power input end.

5. The chemical industry variable power distribution room fan control circuit according to claim 1, characterized in that, The cabinet face local control module comprises at least a first switch, a first stop button, a first start button, a first thermal relay and a first contactor connected in series, the first signal holding module comprises a second contactor connected in parallel across the first start button, the other end of the first switch and the other end of the first contactor are connected to an external three-phase power supply through the power input end, and the first switch is also electrically connected with the state switch.

6. The chemical industry variable power distribution room fan control circuit according to claim 5, characterized in that, The signal control module comprises at least a second switch and a first intermediate relay connected in series, the other end of the second switch is connected to an external three-phase power supply through the power input end, the other end of the first intermediate relay is connected between the first start button and the first thermal relay, and the second switch is also electrically connected with the state switch. The indoor control module comprises at least a second stop button, a second start button, a third stop button and a second intermediate relay connected in series, the other end of the second stop button is connected between the second switch and the first intermediate relay, and the second intermediate relay is connected to an external three-phase power supply through the power input end. The outdoor control module comprises at least a third start button, and the second signal holding module comprises at least a third intermediate relay and a fourth intermediate relay connected in parallel, the third start button is connected in parallel across the second start button, and the third intermediate relay is connected in parallel across the third start button.

7. The chemical industry variable power distribution room fan control circuit according to claim 1, characterized in that, The combustible gas alarm controller linkage module at least includes a combustible gas alarm controller linkage contact and a fifth intermediate relay connected in series, and the other end of the combustible gas alarm controller linkage contact and the other end of the fifth intermediate relay are connected to the secondary side of the isolation transformer.

8. The chemical industry variable power distribution room fan control circuit according to claim 7, characterized in that, The temperature controller linkage module at least includes a temperature controller linkage contact connected in parallel to both ends of the combustible gas alarm controller linkage contact.

9. The chemical industry variable power distribution room fan control circuit according to claim 8, characterized in that, The remote manual control module at least includes a remote manual starting contact connected in parallel to both ends of the temperature controller linkage contact.

10. A fan control system for a chemical plant transformer substation, characterized by, At least including an electrically connected three-phase power supply, a circuit breaker, a contactor, a thermal relay and a fan control circuit of a chemical enterprise transformer substation room as claimed in any one of claims 1-9; The fire line of the three-phase power supply is connected to the fan through the circuit breaker, the contactor and the thermal relay in turn, the fan is also connected with the ground wire of the three-phase power supply, and the zero line and one of the fire lines of the three-phase power supply are connected to the power input end of the fan control circuit of the chemical enterprise transformer substation room.

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