Electrical protection system
By using two series relays and a collector connected to the communication bus in the electrical protection system, real-time monitoring and abnormal alarm of the relay working status is achieved, and the problems of the existing system in fault diagnosis and hardware input signals are solved, improving the safety and flexibility of the system.
Patent Information
- Application Number
- CN202311787914.2
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2023-12-22
- Publication Date
- 2025-06-24
AI Technical Summary
The existing electrical protection systems cannot be diagnosed in a timely manner when there is a sticky fault in the relay, and hardware input signals are required in communicable systems, which adds non-safety factors.
Two relays are used in series, one is a normally open relay and the other is a normally closed relay. The controller is connected to the collector through a communication bus to monitor the working status of the relay in real time, alarm in time and provide abnormal protection.
It improves the safety of the electrical protection system, avoids misdiagnosis caused by faults, increases the flexibility and scalability of the system, and reduces non-safety factors.
Smart Images
Figure CN120200167A_ABST
Abstract
Description
Technical Field
[0001] The present invention relates to the field of electrical technology, and particularly to an electrical protection system.
Background Art
[0002] Figure 1 It is a circuit structure for electrical protection using a safety relay in the prior art. As Figure 1 shown, the A1 and A2 pins of the safety relay are the power supply; T11 and T12 are a pair of input contacts, T21 and T22 are the second pair of input contacts, and the safety relay has an output only when both pairs of contacts are closed; 13 and 14 are a pair of output points, 33 and 34 are the second pair of output points, and when the safety relay outputs, the output points will change to a connected state (13 and 14 are connected, 33 and 34 are connected); Figure 1 In, 13 and 33 are connected to 24V. Therefore, when outputting, 14 and 34 will also become 24V, and the A1 pins of the coils of the relays KM1 and KM2 will be powered by 24V electricity. The A2 pins of the coils are fixedly connected to 0V electricity. Therefore, KM1 and KM2 can be powered to output; T31 and T32 are the feedback diagnosis points of the relays KM1 and KM2. When there is no safe output, T31 and T32 should be connected. After a safe output is performed, T31 and T32 should be disconnected. If the state of the feedback points is abnormal, the safety relay will alarm and disconnect the safe output.
[0003] As Figure 1 shown, when the switches S1 and S2 are safe, the relays KM1 and KM2 are powered. After being powered, the normally open points of KM1 and KM2 are used for safe power supply to a motor or other types. If the normally closed series points (T31 and T32) of the relays KM1 and KM2 are not disconnected, the safety relay will generate an alarm and disconnect the power supply of the relays KM1 and KM2.
[0004] However, the safety relay cannot make a timely diagnosis when the relays KM1 or KM2 have a sticking fault. In addition, the safety relay requires a hardware input signal. If it is applied to a communication-enabled system without a double-loop hardware input signal for emergency stop, it is necessary to separately let the controller form a specific output loop and output loop, which will also increase non-safety factors.
[0005] As Figure 1As shown, if the relay KM1 experiences an adhesion failure due to long-term operation or overcurrent, etc., the safety relay circuit cannot identify this failure. When both switches S1 and S2 are normal, since both relays KM1 and KM2 are energized simultaneously, although the normally closed contact of relay KM1 is stuck, the contact of relay KM2 is open. During safe operation, the two contacts T31 and T32 of the safety relay are also not connected, so the adhesion failure of relay KM1 and its contacts cannot be identified.
[0006] As Figure 2 shown, T11&T12 and T21&T22 connected to switches S1 and S2 must be connected before there can be a safety output. If there are other types of sensor signals, as Figure 3 shown, they need to be relayed through an output relay, and then the output relay is connected in series to the input of the safety relay, resulting in poor flexibility and expandability. In addition, the relays used for relaying also have certain failure rates in terms of lifespan and quality control, etc., which will increase the unsafe factors of the system.
[0007] Therefore, it is necessary to propose a new solution to overcome the problems in the prior art.
[0008] It should be noted that the above introduction of the technical background is only for the convenience of clearly and completely explaining the technical solution of the present application and facilitating the understanding of those skilled in the art. It cannot be considered that the above technical solutions are well-known to those skilled in the art merely because these solutions are described in the background art part of the present application.
Summary of the Invention
[0009] The object of the present invention is to provide an electrical protection system that uses two series-connected relays, one of which is a normally open relay and the other is a normally closed relay. In this way, even if a failure occurs, it is not easy for the two relays to close simultaneously. In addition, the controller can know whether each relay is operating normally, so as to give an alarm in a timely manner when any one of the relays is abnormal, thereby improving safety.
[0010] To achieve the above object, the present invention provides an electrical protection system, which includes: a controller; a collector connected to the controller through a communication bus, the collector including a first sampling terminal, a second sampling terminal, a first control terminal and a second control terminal; a first relay, which includes a first contact, a second contact, a third contact, a fourth contact, a first control terminal, a second control terminal and a coil electrically connected between the first control terminal and the second control terminal. A first normally open switch is formed between the first contact and the second contact of the first relay, and a second normally open switch is formed between the third contact and the fourth contact of the first relay. The third contact of the first relay is electrically connected to the first sampling terminal of the collector, and the first control terminal of the first relay is electrically connected to the first control terminal of the collector; a second relay, which includes a first contact, a second contact, a third contact, a fourth contact, a first control terminal, a second control terminal and a coil electrically connected between the first control terminal and the second control terminal. A first normally closed switch is formed between the first contact and the second contact of the second relay, and a second normally closed switch is formed between the third contact and the fourth contact of the second relay. The third contact of the second relay is electrically connected to the second sampling terminal of the collector, and the first control terminal of the second relay is electrically connected to the second control terminal of the collector. The power supply voltage is supplied externally through the first normally open switch of the first relay and the first normally closed switch of the second relay.
[0011] In one embodiment, the first contact of the first relay receives the power supply voltage, the first contact of the second relay is electrically connected to the second contact of the first relay, and the second contact of the second relay supplies power externally; or, the second contact of the second relay receives the power supply voltage, the first contact of the second relay is electrically connected to the second contact of the first relay, and the first contact of the first relay supplies the power supply voltage externally.
[0012] In one embodiment, the collector controls the coil of the first relay to be energized or de-energized through its first control terminal, and controls the coil of the second relay to be energized or de-energized through its second control terminal. When the coil of the first relay is energized, the first normally open switch and the second normally open switch of the first relay are closed, the first contact of the first relay is electrically connected to the second contact, and the third contact of the first relay is electrically connected to the fourth contact. When the coil of the first relay is de-energized, the first normally open switch and the second normally open switch of the first relay are disconnected, the first contact of the first relay is disconnected from the second contact, and the third contact of the first relay is disconnected from the fourth contact. When the coil of the second relay is energized, the first normally closed switch and the second normally closed switch of the second relay are disconnected, the first contact of the second relay is disconnected from the second contact, and the third contact of the second relay is disconnected from the fourth contact. When the coil of the second relay is de-energized, the first normally closed switch and the second normally closed switch of the second relay are closed, the first contact of the second relay is electrically connected to the second contact, and the third contact of the second relay is electrically connected to the fourth contact.
[0013] In one embodiment, the fourth contact of the first relay is connected to a first predetermined voltage, the second control terminal of the first relay is connected to a second predetermined voltage, the fourth contact of the second relay is connected to a third predetermined voltage, and the second control terminal of the second relay is connected to a fourth predetermined voltage.
[0014] In one embodiment, the controller controls the coil of the first relay to be energized through the collector, and controls the coil of the second relay to be de-energized through the collector. At this time, the first normally open switch and the second normally open switch of the first relay are closed, and the first normally closed switch and the second normally closed switch of the second relay are closed. The controller determines whether the first relay is abnormal based on the voltage at the first sampling terminal of the collector, and determines whether the second relay is abnormal based on the voltage at the second sampling terminal of the collector. If any one of the first relay and the second relay is abnormal, an alarm is given. At the same time, the controller controls the coil of the first relay to be de-energized through the collector, and controls the coil of the second relay to be energized through the collector. If both the first relay and the second relay are normal, the first relay and the second relay operate normally, and the power supply voltage is normally supplied outward through the first relay and the second relay.
[0015] In one embodiment, the controller confirms whether it is safe currently. In a safe situation, the controller controls the coil of the first relay to be energized through the collector, and controls the coil of the second relay to be de-energized through the collector. In an unsafe situation, the controller controls the coil of the first relay to be de-energized through the collector, and controls the coil of the second relay to be energized through the collector. At this time, the first normally open switch and the second normally open switch of the first relay are opened, and the first normally closed switch and the second normally closed switch of the second relay are opened. The controller determines whether the first relay is abnormal based on the voltage at the first sampling terminal of the collector, and determines whether the second relay is abnormal based on the voltage at the second sampling terminal of the collector. If any one of the first relay and the second relay is abnormal, an alarm is given.
[0016] In one embodiment, after the alarm state, if the controller believes that it is safe currently, it still does not control the first relay and the second relay.
[0017] In one embodiment, the electrical protection system further includes: a sensor electrically connected to the controller, which provides a sensing signal to the controller, and the controller confirms whether it is safe currently based on the sensing signal.
[0018] Compared with the prior art, two serially connected relays are adopted in the present invention, one of which is a normally open relay and the other is a normally closed relay. In this way, even if a failure occurs, it is not easy for the two relays to close simultaneously. In addition, the controller can know whether each relay is working properly, so as to give an alarm in time when any one of the relays is abnormal, thereby improving safety.
[0019] Therefore, it should be understood that providing this general overview is only for the purpose of summarizing some embodiments in order to provide a basic understanding of some aspects of the present invention. Therefore, the above embodiments are merely examples and should not be construed as narrowing the scope or concept of the present invention in any way. By reading the following detailed description and the accompanying drawings, the features, appearances and advantages of each embodiment will be obvious, and the drawings show the principles of some embodiments by way of example.
Description of the Drawings
[0020] With reference to the accompanying drawings and the following detailed description, the present invention will be more easily understood, where the same reference numerals correspond to the same structural components, and:
[0021] Figure 1 is the circuit structure for electrical protection using a safety relay in the prior art;
[0022] Figure 2 is an example of using a safety relay for electrical protection;
[0023] Figure 3 is another example of using a safety relay for electrical protection;
[0024] Figure 4 is a schematic diagram of the circuit structure of the electrical protection system in the present invention in one embodiment;
[0025] Figure 5 is Figure 4 the schematic diagram of the first relay KA1 in;
[0026] Figure 6 is Figure 4 the schematic diagram of the second relay KA2 in.
Specific Embodiments
[0027] Some embodiments of the present invention will be described more fully hereinafter with reference to the accompanying drawings, in which some, but not all, embodiments are listed. In fact, the various embodiments of the present invention may be embodied in many different forms and should not be construed as limited to the embodiments set forth herein; rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the present invention to those skilled in the art. For example, unless otherwise stated, referring to something as first, second, etc. should not be construed as implying a particular order. Additionally, something may be described as above something (unless otherwise stated) when in fact it is below, and vice versa; similarly, something described as on the left may be on the right, and vice versa. The same reference numeral always represents the same element.
[0028] The present invention provides an electrical protection system with feedback diagnosis, which uses two series-connected relays, one of which is a normally open relay and the other is a normally closed relay, so that even in case of a fault, it is not easy for the two relays to close simultaneously. In addition, the controller can know whether each relay is working properly, so as to give an alarm in time when any one of the relays is abnormal, thereby improving safety. Additionally, other safety interlock conditions can be conveniently added, increasing the flexibility and scalability of the system.
[0029] Figure 4 It is a schematic circuit diagram of the electrical protection system in an embodiment of the present invention. Figure 5 is Figure 4 a schematic diagram of the structure of the first relay KA1 in Figure 6 is Figure 4 a schematic diagram of the structure of the second relay KA2 in
[0030] As Figures 4 - 6 shown, the electrical protection system includes a controller 310, a collector 320, a first relay KA1, and a second relay KA2.
[0031] The collector 320 is connected to the controller 310 through a communication bus. The communication bus can be various buses, such as a Modbus bus, a Profinet (a new generation of automation bus standard based on industrial Ethernet technology) bus, a CCLink (Control & Communication Link) bus, etc. The collector 320 includes a first sampling terminal DI1, a second sampling terminal DI2, a first control terminal DO1, and a second control terminal DO2.
[0032] The first relay KA1 includes a first contact 1, a second contact 2, a third contact 3, a fourth contact 4, a first control terminal A1, a second control terminal A2, and a coil 9 electrically connected between the first control terminal A1 and the second control terminal A2. The second relay KA2 includes a first contact 1, a second contact 2, a third contact 3, a fourth contact 4, a first control terminal A1, a second control terminal A2, and a coil 9 electrically connected between the first control terminal A1 and the second control terminal A2.
[0033] A first normally open switch is formed between the first contact 1 and the second contact 2 of the first relay KA1, and a second normally open switch is formed between the third contact 3 and the fourth contact 4 of the first relay KA1. The first contact 1 of the first relay KA1 receives the supply voltage. The third contact 3 of the first relay KA1 is electrically connected to the first sampling terminal DI1 of the collector 320, and the first control terminal A1 of the first relay KA1 is electrically connected to the first control terminal DO1 of the collector 320. A first normally closed switch is formed between the first contact 1 and the second contact 2 of the second relay KA2, and a second normally closed switch is formed between the third contact 3 and the fourth contact 4 of the second relay KA2. The first contact 1 of the second relay KA2 is electrically connected to the second contact 2 of the first relay KA1. The second contact 2 of the second relay KA2 supplies power outward. The third contact 3 of the second relay KA2 is electrically connected to the second sampling terminal DI2 of the collector 320, and the first control terminal A1 of the second relay KA2 is electrically connected to the second control terminal DO2 of the collector 320.
[0034] The first normally open switch and the second normally open switch of the first relay KA1 are synchronous, that is, when the first normally open switch is closed, the second normally open switch will also be closed synchronously. When the first normally open switch is opened, the second normally open switch will also be opened synchronously. The first normally closed switch and the second normally closed switch of the second relay KA2 are synchronous, that is, when the first normally closed switch is closed, the second normally closed switch will also be closed synchronously. When the first normally closed switch is opened, the second normally closed switch will also be opened synchronously.
[0035] In another embodiment, the supply voltage can also be received by the second contact 2 of the second relay KA2, and the first contact 1 of the first relay KA1 supplies the supply voltage outward, with the others remaining unchanged, that is, it is equivalent to Figure 4 swapping the positions of the first relay KA1 and the second relay KA2. Generally speaking, the supply voltage supplies power outward through the first normally open switch of the first relay KA1 and the first normally closed switch of the second relay KA2.
[0036] The collector 320 controls the energization or de-energization of the coil 9 of the first relay KA1 through its first control terminal DO1, and controls the energization or de-energization of the coil 9 of the second relay KA2 through its second control terminal DO2. When the coil of the first relay KA1 is energized, the first normally open switch and the second normally open switch of the first relay KA1 are closed, the first contact 1 of the first relay KA1 is electrically connected to the second contact 2, and the third contact 3 of the first relay KA1 is electrically connected to the fourth contact 4. When the coil of the first relay KA1 is de-energized, the first normally open switch and the second normally open switch of the first relay KA1 are opened, the first contact 1 of the first relay KA1 is disconnected from the second contact 2, and the third contact 3 of the first relay KA1 is disconnected from the fourth contact 4. When the coil of the second relay KA2 is energized, the first normally closed switch and the second normally closed switch of the second relay KA2 are opened, the first contact 1 of the second relay KA2 is disconnected from the second contact 2, and the third contact 3 of the second relay KA2 is disconnected from the fourth contact 4. When the coil of the second relay KA2 is de-energized, the first normally closed switch and the second normally closed switch of the second relay KA2 are closed, the first contact 1 of the second relay KA2 is electrically connected to the second contact 2, and the third contact 3 of the second relay KA2 is electrically connected to the fourth contact 4.
[0037] The fourth contact 4 of the first relay KA1 is connected to a first predetermined voltage, the second control terminal A2 of the first relay KA1 is connected to a second predetermined voltage, the fourth contact 4 of the second relay KA2 is connected to a third predetermined voltage, and the second control terminal A2 of the second relay KA2 is connected to a fourth predetermined voltage. For example, the second predetermined voltage and the fourth predetermined voltage can be voltages such as 0V, 24V, 220V, etc., and the second predetermined voltage and the fourth predetermined voltage can be equal or unequal. The first predetermined voltage and the third predetermined voltage can be voltages such as 0V, 24V, etc., and the first predetermined voltage and the third predetermined voltage can be equal or unequal.
[0038] The controller 310 can control the energization or de-energization of the coil of the first relay KA1 through the collector 320, or can control the energization or de-energization of the coil of the second relay KA2 through the collector 320.
[0039] The controller 310 confirms whether it is safe at present. In the case of safety, the controller 310 controls the coil of the first relay KA1 to be energized through the collector 320, and controls the coil of the second relay KA2 to be de-energized through the collector 320. At this time, the first normally open switch and the second normally open switch of the first relay KA1 are closed, and the first normally closed switch and the second normally closed switch of the second relay KA2 are closed. The controller 310 determines whether the first relay KA1 is abnormal based on the voltage of the first sampling terminal DI1 of the collector 320, and determines whether the second relay KA2 is abnormal based on the voltage of the second sampling terminal DI2 of the collector 320. If any of the first relay and the second relay is abnormal, an alarm is issued, and at the same time, the controller 310 controls the coil of the first relay KA1 to be de-energized through the collector 320, and controls the coil of the second relay KA2 to be energized through the collector 320, so as to further perform abnormal protection. If both the first relay KA1 and the second relay KA2 are normal, the first relay KA1 and the second relay KA2 work normally, and the power supply voltage is normally supplied to the outside through the first relay KA1 and the second relay KA2.
[0040] In an unsafe situation, the controller 310 controls the coil of the first relay KA1 to lose power through the collector 320, and controls the coil of the second relay KA2 to be powered through the collector 320. At this time, the first normally open switch and the second normally open switch of the first relay KA1 are disconnected, and the first normally closed switch and the second normally closed switch of the second relay KA2 are disconnected to perform power-off protection. At this time, the controller 310 determines whether the first relay KA1 is abnormal based on the voltage of the first sampling terminal DI1 of the collector 320, and determines whether the second relay KA2 is abnormal based on the voltage of the second sampling terminal DI2 of the collector 320. If any of the first relay and the second relay is abnormal, an alarm is issued. After the alarm state, if the controller 310 believes that it is safe at present, it will no longer control the first relay and the second relay until the alarm state is released after manual inspection.
[0041] If the first relay KA1 and the second relay KA2 are operating normally, then the voltage at the first sampling terminal DI1 will be equal to the predetermined expected voltage in the corresponding state, and the voltage at the second sampling terminal DI2 will be equal to the predetermined expected voltage in the corresponding state. That is to say, if the voltage at the first sampling terminal DI1 is not equal to the predetermined expected voltage in the corresponding state, it is considered that the first relay KA1 is abnormal. For example, due to various reasons, the first normally open switch of the first relay KA1 should be open but is not open, or should be closed but is not closed. Similarly, if the voltage at the second sampling terminal DI2 is not equal to the predetermined expected voltage in the corresponding state, it is considered that the second relay KA2 is abnormal. For example, due to various reasons, the first normally closed switch of the second relay KA2 should be closed but is not closed, or should be open but is not open.
[0042] In one embodiment, the electrical protection system further includes: a sensor electrically connected to the controller 310, the sensor can provide a sensing signal to the controller 310, and the controller 310 determines whether it is safe currently based on the sensing signal. For example, the sensor can be a temperature sensor, and the controller 310 determines whether it is safe currently based on the temperature. Of course, the sensor can also be other sensors, such as a current sensor or a voltage sensor, and the controller 310 determines whether it is safe currently based on the current value sensed by the current sensor and / or the voltage value sensed by the voltage sensor.
[0043] The sensor can be connected to the controller 310 through the collector, or can be directly connected to the controller 310. It can be seen that the present invention can easily add safety interlock conditions without using an intermediate relay for transfer, increasing the flexibility and scalability of the system.
[0044] In an alternative embodiment, the controller 310 may not determine whether it is safe currently, but may default that it is safe at that time, so as to control and diagnose the first relay KA1 and the second relay KA2 through the collector 320.
[0045] In summary, the electrical protection system with feedback diagnosis of the present invention has the following advantages or characteristics:
[0046] 1) Two series-connected relays KA1 and KA2 are adopted, one of which is a normally open relay and the other is a normally closed relay. In this way, even if a failure occurs and the coils of KA1 and KA2 are both energized, KA1 and KA2 will not close simultaneously. If there is a hardware failure at the output end, such as the control power supply line is disconnected, resulting in KA1 and KA2 not being able to be energized, at this time, KA1 and KA2 still will not close simultaneously and still will not supply power externally.
[0047] 2) The controller can know whether each relay is working properly, so as to give an alarm in time when any relay has an abnormality, thereby improving safety.
[0048] 3) Safety interlock conditions can be added very conveniently without using intermediate relays for transfer, which increases the flexibility and scalability of the system. For example, if five communicable temperature control sensors are added, they can directly communicate with the controller without adding additional hardware.
[0049] Combined with the description of the accompanying drawings and the specific embodiments of the present invention, the details of the present invention can be understood more clearly. However, the specific embodiments of the present invention described herein are only for the purpose of explaining the present invention and cannot be construed in any way as a limitation of the present invention. Under the teaching of the present invention, those skilled in the art can conceive any possible variations based on the present invention, and these should all be regarded as belonging to the scope of the present invention. It should be noted that when an element is referred to as being "disposed on" another element, it can be directly on the other element or there may also be an intermediate element. When an element is considered to be "connected" to another element, it can be directly connected to the other element or there may be an intermediate element at the same time.
[0050] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by those of ordinary skill in the technical field to which this application belongs. The terms used in the specification of this application herein are only for the purpose of describing specific embodiments and are not intended to limit this application. The term "and / or" used herein includes any and all combinations of one or more of the related listed items.
[0051] Many modifications and other embodiments of the present invention relate to those skilled in the art, who have relevant industry knowledge and some original data. Therefore, it should be understood that the present invention is not limited to the specific embodiments disclosed, but also includes other embodiments modified within the scope of the appended claims. In addition, although the foregoing description and the related drawings describe the implementation of specific embodiments of elements and functions in combination, within the scope of the appended claims, different combinations of elements and functions achieved by substitution are also included. The appended claims also include combinations of elements and functions different from those clearly described above. Although specific terms are used herein, they are only for general descriptive purposes and not for limiting purposes.
Claims
1. An electrical protection system, characterized in that, It includes: A controller; A collector connected to the controller through a communication bus, which includes a first sampling terminal, a second sampling terminal, a first control terminal, and a second control terminal; A first relay, which includes a first contact, a second contact, a third contact, a fourth contact, a first control terminal, a second control terminal, and a coil electrically connected between the first control terminal and the second control terminal. A first normally open switch is formed between the first contact and the second contact of the first relay, and a second normally open switch is formed between the third contact and the fourth contact of the first relay. The third contact of the first relay is electrically connected to the first sampling terminal of the collector, and the first control terminal of the first relay is electrically connected to the first control terminal of the collector; A second relay, which includes a first contact, a second contact, a third contact, a fourth contact, a first control terminal, a second control terminal, and a coil electrically connected between the first control terminal and the second control terminal. A first normally closed switch is formed between the first contact and the second contact of the second relay, and a second normally closed switch is formed between the third contact and the fourth contact of the second relay. The third contact of the second relay is electrically connected to the second sampling terminal of the collector, and the first control terminal of the second relay is electrically connected to the second control terminal of the collector; The power supply voltage supplies power outward through the first normally open switch of the first relay and the first normally closed switch of the second relay.
2. The electrical protection system according to claim 1, wherein The first contact of the first relay receives the power supply voltage. The first contact of the second relay is electrically connected to the second contact of the first relay, and the second contact of the second relay supplies power outward; or, the second contact of the second relay receives the power supply voltage. The first contact of the second relay is electrically connected to the second contact of the first relay, and the first contact of the first relay supplies the power supply voltage outward.
3. The electrical protection system according to claim 2, characterized in that, The collector controls the coil of the first relay to be energized or de-energized through its first control terminal, and controls the coil of the second relay to be energized or de-energized through its second control terminal. When the coil of the first relay is energized, the first normally open switch and the second normally open switch of the first relay close. The first contact of the first relay is electrically connected to the second contact, and the third contact of the first relay is electrically connected to the fourth contact. When the coil of the first relay is de-energized, the first normally open switch and the second normally open switch of the first relay open. The first contact of the first relay is disconnected from the second contact, and the third contact of the first relay is disconnected from the fourth contact. When the coil of the second relay is energized, the first normally closed switch and the second normally closed switch of the second relay open. The first contact of the second relay is disconnected from the second contact, and the third contact of the second relay is disconnected from the fourth contact. When the coil of the second relay is de-energized, the first normally closed switch and the second normally closed switch of the second relay close. The first contact of the second relay is electrically connected to the second contact, and the third contact of the second relay is electrically connected to the fourth contact.
4. The electrical protection system according to claim 2, wherein The fourth contact of the first relay is connected to a first predetermined voltage, the second control terminal of the first relay is connected to a second predetermined voltage, the fourth contact of the second relay is connected to a third predetermined voltage, and the second control terminal of the second relay is connected to a fourth predetermined voltage.
5. The electrical protection system according to claim 3, wherein the controller controls the coil of the first relay to be energized through the collector, and controls the coil of the second relay to be de-energized through the collector. At this time, the first normally open switch and the second normally open switch of the first relay are closed, and the first normally closed switch and the second normally closed switch of the second relay are closed; the controller determines whether the first relay is abnormal based on the voltage at the first sampling terminal of the collector, and determines whether the second relay is abnormal based on the voltage at the second sampling terminal of the collector; if any one of the first relay and the second relay is abnormal, an alarm is given. At the same time, the controller controls the coil of the first relay to be de-energized through the collector, and controls the coil of the second relay to be energized through the collector; if both the first relay and the second relay are normal, the first relay and the second relay work normally, and the power supply voltage is normally supplied to the outside through the first relay and the second relay.
6. The electrical protection system according to claim 5, wherein the controller confirms whether it is safe currently; in a safe situation, the controller controls the coil of the first relay to be energized through the collector, and controls the coil of the second relay to be de-energized through the collector; in an unsafe situation, the controller controls the coil of the first relay to be de-energized through the collector, and controls the coil of the second relay to be energized through the collector. At this time, the first normally open switch and the second normally open switch of the first relay are opened, and the first normally closed switch and the second normally closed switch of the second relay are opened; the controller determines whether the first relay is abnormal based on the voltage at the first sampling terminal of the collector, and determines whether the second relay is abnormal based on the voltage at the second sampling terminal of the collector. If any one of the first relay and the second relay is abnormal, an alarm is given.
7. The electrical protection system according to claim 6, wherein after the alarm state, if the controller believes that it is safe currently, it still does not control the first relay and the second relay.
8. The electrical protection system according to claim 6, characterized in that, It further includes: a sensor electrically connected to the controller, which provides a sensing signal to the controller, and the controller confirms whether it is safe currently based on the sensing signal.