Overcurrent protection system

Abstract

The utility model discloses an overcurrent protection system, and relates to the technical field of overcurrent protection, the overcurrent protection system is connected in series between an input end and an output end of a load loop, the overcurrent protection system comprises a PTC thermistor and a bypass device, the PTC thermistor is connected in series in the load loop, and the bypass device and the PTC thermistor are arranged in parallel to form a bypass loop; when the current is normal, the bypass device is short-circuited, and the electrical equipment operates normally; when the current is increased and overcurrent occurs, the bypass device is open, and the PTC thermistor is connected in series to the circuit, so that the current of the whole load loop is reduced, and electrical equipment is protected; the bypass device is connected in parallel to the two ends of the PTC thermistor, so that the PTC thermistor only works during overcurrent protection, the working time of the PTC thermistor is shortened, the electric energy loss is reduced, and meanwhile, the phenomenon that current in a circuit is influenced by external temperature and is unstable is avoided.

Description

Technical Field

[0001] The utility model relates to the technical field of overcurrent protection, and particularly relates to an overcurrent protection system. Background Art

[0002] For electrical equipment in a power system, when the current increases due to external reasons (such as excessive load, short-circuit fault, etc.) and causes overcurrent in the circuit, it is easy for the circuit to overheat and cause a fire or the equipment to overheat and be damaged.

[0003] Regarding the overcurrent phenomenon, there are many traditional overcurrent protection methods. For example, a fuse, when the current increases to a certain value, the current causes the temperature of the fuse to rise until it melts, and the current is cut off. For example, a bimetallic thermal bending circuit breaker, the pressure piece of the circuit breaker is made of bimetallic. When the current increases, due to the difference in the thermal expansion coefficients of different metals, the metal bends and releases the switch contacts to disconnect, thus cutting off the current. In traditional protection methods, the circuit and equipment are protected by adopting the method of interrupting the current.

[0004] With the development of technology, the method of overcurrent protection is no longer simply interrupting the current. For example, a PTC thermistor is adopted. The PTC thermistor has a positive temperature coefficient characteristic, that is, as the temperature rises, its resistance value will increase significantly. This characteristic enables the PTC thermistor to automatically adjust the resistance value according to the magnitude of the current in overcurrent protection, thereby restricting the current passing through and preventing the circuit and equipment from overheating.

[0005] However, there are still the following problems with the scheme of using a PTC thermistor for overcurrent protection: when the PTC thermistor is connected to the circuit for overcurrent protection, since the PTC thermistor has a basic resistance, part of the electrical energy passing through the PTC thermistor will be lost during use, and a large amount of electrical energy will be lost after long-term use. Moreover, the PTC thermistor is easily affected by the ambient temperature during use, causing the resistance to fluctuate, and further making the current in the circuit unstable and the operation of the electrical equipment unstable.

[0006] Therefore, it is urgent to design an overcurrent protection system to solve the above problems. Content of the Utility Model

[0007] In order to overcome the above technical problems, the purpose of the utility model is to provide an overcurrent protection system. By connecting a bypass device in parallel at both ends of the PTC thermistor, the PTC thermistor only works during overcurrent protection, solving the problems of the working time of the PTC thermistor, power loss, and the instability of the current in the circuit caused by the influence of the external temperature.

[0008] The purpose of the utility model can be realized by the following technical solutions:

[0009] An overcurrent protection system is connected in series between the input end and the output end of a load circuit, and includes a PTC thermistor and a bypass device. The PTC thermistor is connected in series to the load circuit, and the bypass device is arranged in parallel with the PTC thermistor to form a bypass circuit;

[0010] When the current is normal, the bypass device is short-circuited and the electrical equipment operates normally;

[0011] When the current is overcurrent, the bypass device is open-circuited, and the PTC thermistor is connected in series to the circuit, causing the current of the entire load circuit to drop and protecting the electrical equipment.

[0012] As a further solution of the present utility model: the bypass device is a normally open switch or a normally closed switch.

[0013] As a further solution of the present utility model: the bypass device includes a current monitoring module, a control switch, and a control module. The current monitoring module is arranged in the load circuit, and the current monitoring module is electrically connected to the control module, and the control module is electrically connected to the control switch.

[0014] As a further solution of the present utility model: the current monitoring module monitors the current of the load circuit in real time, sends the real-time monitored current data to the control module, the control module processes the data, sends out a signal according to the processing result, and the control switch realizes the closing or opening action according to the signal.

[0015] As a further solution of the present utility model: the specific process of the control module processing the data is as follows: the current monitoring module obtains the real-time current value of the load circuit and sends it to the control module, and the control module compares the received real-time current value with a preset current threshold;

[0016] If the real-time current value is greater than the current threshold, it is determined to be in an overcurrent state, a disconnection signal is generated and sent to the control switch to disconnect the bypass circuit;

[0017] If the real-time current value is less than or equal to the current threshold, it is determined to be in a normal state, a closing signal is generated and sent to the control switch to connect the bypass circuit.

[0018] As a further solution of the present utility model: the control switch includes a first power connection block and a second power connection block on the bypass circuit, and the control switch further includes a control base. A control cavity is arranged inside the control base, a spring is arranged in the control cavity, the other end of the spring is connected with an electrical connection member, and an electromagnet I is arranged in the control cavity. The electromagnet I is energized to adsorb the electrical connection member.

[0019] As a further solution of the present utility model: the electrical connection member is a first electrical connection knife switch.

[0020] As a further solution of the present utility model: a timer is further arranged in the current monitoring module, and the specific process of the control module processing the data is as follows:

[0021] The current monitoring module obtains the real-time current value of the load circuit and sends it to the control module, and the control module compares the received real-time current value with a preset current threshold;

[0022] If the real-time current value is greater than the current threshold, it is determined to be in an overcurrent state, and a timer is started. When the timing duration is greater than the preset time threshold, a disconnection signal is generated and sent to the control switch to disconnect the bypass circuit; when the timing duration is less than or equal to the preset time threshold, a closing signal is generated and sent to the control switch to connect the bypass circuit;

[0023] If the real-time current value is less than or equal to the current threshold, it is determined to be in a normal state, no timing is performed, a closing signal is generated and sent to the control switch to connect the bypass circuit.

[0024] As a further solution of the present utility model: corresponding closing grooves are provided on the opposite sides of the first power connection block and the second power connection block, limiting card slots are symmetrically provided at the bottom of the control cavity of the control base, and the power connection member is a power connection knife switch II. An insulating top plate is provided on the top of the power connection knife switch II, and an electromagnet II is installed on the insulating top plate.

[0025] As a further solution of the present utility model: the power connection knife switch II has an elastic frame-shaped structure, and clamping platforms are provided on both sides of the frame shape of the power connection knife switch II, and the clamping platforms are adapted to both the closing groove and the limiting card slot.

[0026] As a further solution of the present utility model: a resistor is further provided in the load circuit, the resistor is connected in series with the PTC thermistor, and the resistor is connected in parallel with the bypass device.

[0027] As a further solution of the present utility model: an inductor is further provided in the load circuit, the inductor is connected in series with the PTC thermistor, and the inductor is connected in parallel with the bypass device.

[0028] As a further solution of the present utility model: an inductor and a resistor are further provided in the load circuit, the inductor is connected in series with the PTC thermistor, the inductor is connected in parallel with the resistor, and the resistor is connected in parallel with the bypass device.

[0029] As a further solution of the present utility model: an inductor and a resistor are further provided in the load circuit, and both the inductor and the resistor are connected in series in the load circuit, and both the inductor and the resistor are connected in parallel with the bypass device.

[0030] The beneficial effects of the present utility model:

[0031] 1. By connecting a bypass device in parallel at both ends of the PTC thermistor, the PTC thermistor only works during overcurrent protection, reducing the working duration of the PTC thermistor, reducing power consumption, and at the same time avoiding the phenomenon that the current in the circuit is affected by the external temperature and becomes unstable.

[0032] 2. The utility model replaces the power connection knife switch 1 with an elastic frame-shaped structure power connection knife switch 2. At the same time, corresponding closing grooves are opened on the opposite side surfaces of the first power connection block and the second power connection block, and limiting card slots are symmetrically opened at the bottom of the control cavity of the control base, so that the power connection knife switch 2 is engaged with the closing groove when closed and engaged with the limiting card slot when disconnected, without continuously energizing the electromagnet 1 and / or the electromagnet 2, thus solving the problem of electric energy. Brief Description of the Drawings

[0033] The following further describes the present utility model with reference to the drawings.

[0034] Figure 1 It is a schematic structural diagram of the overcurrent protection system of the present utility model;

[0035] Figure 2 It is a schematic structural diagram of the control switch in Embodiment 3 of the present utility model;

[0036] Figure 3 It is a schematic diagram of the closed state of the control switch in Embodiment 5 of the present utility model;

[0037] Figure 4 It is a schematic diagram of the open state of the control switch in Embodiment 5 of the present utility model;

[0038] Figure 5 It is a schematic structural diagram of the power connection knife switch 2 of the present utility model;

[0039] Figure 6 It is a schematic structural diagram of Embodiment 6 of the present utility model;

[0040] Figure 7 It is a schematic structural diagram of Embodiment 7 of the present utility model;

[0041] Figure 8 It is a schematic structural diagram of Embodiment 8 of the present utility model;

[0042] Figure 9 It is a schematic structural diagram of Embodiment 9 of the present utility model.

[0043] In the figure: 1, PTC thermistor; 2, bypass device; 21, current monitoring module; 22, control switch; 221, first power connection block; 222, second power connection block; 223, control base; 224, control cavity; 225, spring; 226, electromagnet 1; 227, power connection knife switch 1; 228, limiting card slot; 229, power connection knife switch 2; 230, closing groove; 231, electromagnet 2; 232, insulating top plate; 233, clamping platform; 23, control module. Detailed Embodiments

[0044] The following will clearly and completely describe the technical solutions in the embodiments of the present utility model in conjunction with the accompanying drawings in the embodiments of the present utility model. Obviously, the described embodiments are only a part of the embodiments of the present utility model, rather than all the embodiments. Based on the embodiments of the present utility model, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present utility model.

[0045] As shown in the present utility model Figures 1 - 5 A overcurrent protection system is designed. By connecting a bypass device 2 in parallel across the two ends of the PTC thermistor 1, the PTC thermistor 1 only works during overcurrent protection, reducing the working duration of the PTC thermistor 1, lowering power consumption, and at the same time avoiding the influence of the current in the circuit by the external temperature, resulting in unstable phenomena.

[0046] Embodiment 1

[0047] As Figure 1 shown, the above-mentioned overcurrent protection system is connected in series between the input end and the output end of the load circuit to perform overcurrent protection on the electrical equipment. The overcurrent protection system includes a PTC thermistor 1 and a bypass device 2. Among them, the PTC thermistor 1 is connected in series to the load circuit, and the bypass device 2 is arranged in parallel with the PTC thermistor 1 to form a bypass circuit;

[0048] When the current is normal, the bypass device 2 is short-circuited to realize the bypass of the PTC thermistor 1. The current flows from the input end through the short-circuited bypass device 2 and out from the output end to realize the normal operation of the electrical equipment;

[0049] When the current increases and is overcurrent, the bypass device 2 is open-circuited, and the PTC thermistor 1 is connected in series to the circuit. Since it is in an overcurrent state at this time, the current will flow through the PTC thermistor 1, and the PTC thermistor 1 will heat up. As the temperature rises, the resistance value of the PTC thermistor 1 will become larger and larger. Due to the increasing resistance value, the current flowing through the PTC thermistor 1 will become smaller and smaller. When the resistance is large enough, the PTC thermistor 1 will form a thermal balance, causing the current of the entire load circuit to rapidly drop to the milliampere level, thereby realizing the overcurrent or short-circuit protection function of the electrical equipment.

[0050] Embodiment 2

[0051] In this embodiment, the bypass device 2 is a normally open switch or a normally closed switch, which is closed when the current is normal and opened when the current increases and is overcurrent to realize the connection of the PTC thermistor 1 and protect the electrical equipment from overcurrent or short-circuit.

[0052] Embodiment 3

[0053] In this embodiment, the bypass device 2 includes a current monitoring module 21, a control switch 22, and a control module 23. The current monitoring module 21 monitors the current of the load circuit in real time and sends the real-time monitored current data to the control module 23. The control module 23 processes the data, sends out a signal according to the processing result, and the control switch 22 realizes the closing or opening action according to the signal.

[0054] Further, as Figure 2 shown, the control switch 22 includes a first power connection block 221 and a second power connection block 222 on the bypass circuit. The control switch 22 further includes a control base 223. A control cavity 224 is arranged inside the control base 223. A first power connection knife 227 is connected by a spring 225 in the control cavity 224. Further, an electromagnet 226 is arranged in the control cavity 224. The on-off state control of the connection between the first power connection knife 227 and the first power connection block 221 and the second power connection block 222 is realized by controlling the on-off of the electromagnet 226.

[0055] The specific control process is as follows:

[0056] The real-time current value of the load circuit is obtained through the current monitoring module 21 and sent to the control module 23. The control module 23 compares the received real-time current value with a preset current threshold.

[0057] If the real-time current value is greater than the current threshold, it is determined to be an overcurrent state, a disconnection signal is generated and sent to the control switch 22. After receiving the disconnection signal, the control switch 22 continuously energizes the electromagnet 226 to adsorb the first power connection knife 227, disconnecting the connection between the first power connection knife 227 and the first power connection block 221 and the second power connection block 222, realizing the open circuit of the bypass circuit, enabling the access of the PTC thermistor 1, and protecting the electrical equipment.

[0058] If the real-time current value is less than or equal to the current threshold, it is determined to be a normal state, a closing signal is generated. The control switch 22 does not energize the electromagnet 226 after receiving the closing signal, and the first power connection knife 227 is pushed by the spring 225 to connect with the first power connection block 221 and the second power connection block 222, enabling the normal operation of the electrical equipment.

[0059] Embodiment 4

[0060] Further, on the basis of Embodiment 3, this embodiment monitors the overcurrent time. A timer is added to the current monitoring module 21 in Embodiment 3. When the real-time current value is greater than the current threshold and it is determined to be in an overcurrent state, the timer is started to count. When the counting duration is greater than a preset time threshold, a disconnection signal is generated, and the bypass circuit is disconnected as in Embodiment 3, enabling the access of the PTC thermistor 1 to protect the electrical equipment. When the counting duration is less than or equal to the preset time threshold, a closing signal is generated and sent to the control switch 22 to connect the bypass circuit.

[0061] When the real-time current value is less than or equal to the current threshold and it is determined to be in the normal state, no timing is performed, a closing signal is generated and sent to the control switch 22 to turn on the bypass circuit.

[0062] Embodiment 5

[0063] Since it is necessary to continuously energize the electromagnet 1 226 when the control switch 22 is disconnected, in order to solve the problem that a large amount of electric energy is consumed when the control switch 22 remains in the open state for a long time in the overcurrent state, resulting in a reduction in energy utilization rate, on the basis of Embodiment 2 or Embodiment 3, the structure of the control switch 22 is improved. By using an elastic frame-shaped structure to connect the second knife switch 229 instead of the first knife switch 227, and at the same time, corresponding closing grooves 230 are opened on the opposite sides of the first connection block 221 and the second connection block 222, and limiting card slots 228 are symmetrically opened at the bottom of the control cavity 224 of the control base 223, so that the second knife switch 229 is engaged with the closing groove 230 when closed and engaged with the limiting card slot 228 when opened, without continuously energizing the electromagnet 1 226 and / or the electromagnet 2 231, thus solving the problem of electric energy.

[0064] As shown in Figures 3 - 5 corresponding closing grooves 230 are opened on the opposite sides of the first connection block 221 and the second connection block 222, and limiting card slots 228 are symmetrically opened at the bottom of the control cavity 224 of the control base 223. The second knife switch 229 is used to replace the first knife switch 227. An insulating top plate 232 is provided at the top of the second knife switch 229, and an electromagnet 2 231 is installed on the insulating top plate 232. And the second knife switch 229 is in an elastic frame-shaped structure, and clamping platforms 233 are provided on both sides of the frame of the second knife switch 229; the clamping platforms 233 are adapted to both the closing groove 230 and the limiting card slot 228.

[0065] When the control switch 22 receives the disconnection signal, the electromagnet 1 226 and the electromagnet 2 231 are energized in the same direction (the current directions are the same), the electromagnet 1 226 and the electromagnet 2 231 attract each other, driving the second knife switch 229 to retract, so that the clamping platform 233 of the second knife switch 229 is engaged with the limiting card slot 228. After the engagement, the energized states of the electromagnet 1 226 and the electromagnet 2 231 are disconnected, and the second knife switch 229 can still be stably engaged in the two limiting card slots 228 to realize the open circuit of the bypass circuit.

[0066] When the control switch 22 receives a closing signal, it supplies reverse electric currents (with opposite current directions) to the first electromagnet 226 and the second electromagnet 231, causing the first electromagnet 226 and the second electromagnet 231 to repel each other. Combining with the elastic force of the spring 225, it makes the second power switch blade 229 engage with the closing slots 230 of the first power connection block 221 and the second power connection block 222. After the engagement, the power supply to the first electromagnet 226 and the second electromagnet 231 is cut off, maintaining the short circuit of the bypass circuit and realizing the normal operation of the electrical equipment.

[0067] Embodiment 6

[0068] As Figure 6 shown, based on Embodiment 1, a resistor is further provided in the load circuit. The resistor is connected in series with the PTC thermistor 1 and in parallel with the bypass device 2. By increasing the basic resistance in the over-current state of the load circuit, the over-current protection ability is further improved.

[0069] Embodiment 7

[0070] As Figure 7 shown, based on Embodiment 1, an inductor is further provided in the load circuit. The inductor is connected in series with the PTC thermistor 1 and in parallel with the bypass device 2. By increasing the basic resistance in the over-current state of the load circuit, the over-current protection ability is further improved.

[0071] Embodiment 8

[0072] As Figure 8 shown, based on Embodiment 1, an inductor and a resistor are further provided in the load circuit. The inductor is connected in series with the PTC thermistor 1, the inductor is connected in parallel with the resistor, and the resistor is connected in parallel with the bypass device 2. By increasing the basic resistance in the over-current state of the load circuit, the over-current protection ability is further improved.

[0073] Embodiment 9

[0074] As Figure 9 shown, based on Embodiment 1, an inductor and a resistor are further provided in the load circuit, and both the inductor and the resistor are connected in series in the load circuit and in parallel with the bypass device 2. By increasing the basic resistance in the over-current state of the load circuit, the over-current protection ability is further improved.

[0075] In the description of the present utility model, it should be understood that the terms "upper", "lower", "left", "right", etc. indicating the orientation or position relationship are based on the orientation or position relationship shown in the drawings, and are only for the convenience of describing the present utility model and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, as well as a specific orientation structure and operation. Therefore, it should not be construed as a limitation to the present utility model. In addition, "first" and "second" are only for the purpose of description, and cannot be understood as indicating or implying relative importance or implicitly specifying the quantity of the indicated technical features. Therefore, the features defined with "first" and "second" may explicitly or implicitly include one or more of such features. In the description of the present utility model, unless otherwise specified, the meaning of "a plurality of" is two or more than two.

[0076] In the description of the present utility model, it should be noted that unless otherwise clearly specified and defined, the terms "installed", "connected", "connected", etc. should be understood in a broad sense. For example, it may be a fixed connection, a detachable connection, or an integral connection; it may be a mechanical connection or an electrical connection; it may be directly connected, or indirectly connected through an intermediate medium, and it may be the communication inside two elements. For those of ordinary skill in the art, the specific meanings of the above terms in the present utility model can be understood according to specific circumstances.

[0077] The above has described in detail an embodiment of the present utility model, but the content described is only the preferred embodiment of the present utility model and cannot be considered as used to limit the scope of implementation of the present utility model. All equivalent changes and improvements made according to the scope of the application of the present utility model should still fall within the scope covered by the patent of the present utility model.

Claims

1. An overcurrent protection system, which is connected in series between the input and output ends of a load circuit, characterized in that: It comprises a PTC thermistor (1) and a bypass device (2), wherein the PTC thermistor (1) is connected in series to a load circuit, and the bypass device (2) is arranged in parallel with the PTC thermistor (1) to form a bypass circuit; When the current is normal, the bypass device (2) is short-circuited; When the current is too high, the bypass device (2) opens.

2. An overcurrent protection system according to claim 1, characterized in that: The bypass device (2) comprises a current monitoring module (21), a control switch (22) and a control module (23); the current monitoring module (21) is arranged in a load circuit, the current monitoring module (21) is electrically connected to the control module (23), and the control module (23) is electrically connected to the control switch (22).

3. An overcurrent protection system according to claim 2, characterized in that: The control switch (22) comprises a first power connection block (221) and a second power connection block (222) on a bypass circuit, and the control switch (22) further comprises a control base (223), a control chamber (224) is arranged inside the control base (223), a spring (225) is arranged in the control chamber (224), the other end of the spring (225) is connected to the power connection piece, an electromagnet (226) is arranged in the control chamber (224), and the electromagnet (226) is energized to attract the power connection piece.

4. An overcurrent protection system according to claim 3, characterized in that: The power connection part is a power switch 1 (227).

5. An overcurrent protection system according to claim 3, characterized in that: The first power connection block (221) and the second power connection block (222) are provided with corresponding closed grooves (230) on opposite sides, the control cavity (224) of the control base (223) is symmetrically provided with limit slots (228) at the bottom, and the power connection component is a second power connection knife (229), the top of which is provided with an insulating top plate (232), and a second electromagnet (231) is installed on the insulating top plate (232).

6. An overcurrent protection system according to claim 5, characterized in that: The second power switch (229) is in the form of a flexible frame. A clamping platform (233) is arranged on both sides of the frame of the second power switch (229). The clamping platform (233) is adapted to the closing slot (230) and the limiting clamping slot (228).

7. An overcurrent protection system according to any one of claims 1 to 6, characterized in that: A resistor is also provided in the load circuit. The resistor is connected in series with the PTC thermistor (1), and is connected in parallel with the bypass device (2).

8. An overcurrent protection system according to any one of claims 1 to 6, characterized in that: An inductor is also provided in the load circuit. The inductor is connected in series with the PTC thermistor (1), and the inductor is connected in parallel with the bypass device (2).

9. An overcurrent protection system according to any one of claims 1 to 6, characterized in that: An inductor and a resistor are also provided in the load circuit. The inductor is connected in series with the PTC thermistor (1), the inductor is connected in parallel with the resistor, and the resistor is connected in parallel with the bypass device (2).

10. An overcurrent protection system according to any one of claims 1 to 6, characterized in that: An inductor and a resistor are also provided in the load circuit, and the inductor and the resistor are both connected in series in the load circuit, and the inductor and the resistor are both connected in parallel with the bypass device (2).

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