CN212183096U - Reliable self-recovery power output overcurrent protection device - Google Patents
Reliable self-recovery power output overcurrent protection device Download PDFInfo
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- CN212183096U CN212183096U CN202021074002.2U CN202021074002U CN212183096U CN 212183096 U CN212183096 U CN 212183096U CN 202021074002 U CN202021074002 U CN 202021074002U CN 212183096 U CN212183096 U CN 212183096U
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Abstract
The utility model relates to a reliable self-recovery power output overcurrent protection device, the overcurrent protection circuit comprises a triode T1, a T2 and a self-reset fuse R47; the overcurrent protection circuit specifically comprises: the resistor R11 and the resistor R12 are connected with the direct current output power supply and then connected in parallel, and after being connected in parallel, the resistors R10 are connected in series and then connected with the B pole of the triode T1; the C pole of the triode T1 is connected with one end of a resistor R8, and the other end of the resistor R8 is the output negative pole of the power supply; one end of the resistor R9 is connected with the C pole of the triode T1, and the other end of the resistor R9 is connected with the B pole of the triode T2; the C electrode of the T2 of the triode is connected with one end of a self-recovery fuse R47; the other end of the self-reset fuse R47 is the output anode of the power supply; the gas discharge tube is connected in parallel between the output anode of the power supply and the output cathode of the power supply; the transistor T2 and the resistor R47 are tightly arranged and welded on the large bonding pad which is fully coated with the soldering tin. The device is strong in practicability.
Description
Technical Field
The utility model relates to an alarm device field, concretely relates to reliable self resuming power output overcurrent protection device.
Background
Various alarm systems on the market at present all comprise alarm control host computer and various front end detectors, and alarm control host computer generally all possesses 12V direct current output voltage and supplies power for host computer peripheral equipment (such as control keyboard, detector), as shown in figure 1, based on alarm system needs high reliable environmental suitability requirement, this power output must possess better maximum output current restriction ability and certain output protection ability (such as current-limiting, output short-circuit protection, restrain high-voltage input etc.), and common protection method and the not enough analysis of existence are as follows: (1) the protection method of the fast fusing fuse comprises the following steps: this is the most traditional and simplest protection method, and when the circuit current exceeds the fuse blowing threshold, the fuse blows, thereby disconnecting the external output load for protection. The method is simple to realize and has extremely low cost, but has obvious defects that on one hand, the current limiting precision of the protection is lower due to the characteristic of quickly fusing the fuse, and on the other hand, once the fuse is fused due to overload of an output part, the alarm system breaks down to cause the alarm system to lose the safety protection capability; therefore, technicians are required to go to field maintenance service to recover the normal work of the alarm system as soon as possible, and obviously, the alarm system has potential safety hazards in the period before repair. (2) The self-recovery fuse protection method comprises the following steps: based on the working characteristics of the self-recovery fuse, the method seems to solve the defects existing in the quick fuse and play a role in current limiting protection, but in practical use, the method also has serious defects, and besides the problem of current limiting precision, when an alarm system is connected with a large output load, the fuse element can generate heat by itself or external environment to cause the increase of impedance of the fuse element, so that the voltage drop of the fuse element is increased to cause the reduction of the voltage of the output load, and the false alarm phenomenon of an external detector of the alarm system due to low power supply voltage appears, and obviously, the defects are also fatal defects for the alarm system. (3) The protection method of the power triode constant current source circuit is adopted by many professional alarm hosts at present, the problem of current limiting protection precision is well solved by the protection method with low cost, and the maximum output current can be accurately controlled by adjusting the resistance values R11 and R12 of the current limiting resistors, as shown in figure 1. And the short circuit of the power output end in a short time can also play a role in protection, and the short circuit fault can still work normally after being discharged. However, in the actual use process, the power output is often in a short-circuit state for a long time, and the power transistor T2 is in an output short-circuit state for a long time, so that the transistor is burnt due to overhigh temperature, and finally the alarm system cannot work normally.
Disclosure of Invention
1. The technical problem to be solved is as follows:
to the technical problem, the utility model provides a reliable self recovery power output overcurrent protection device, including protection circuit and heat-conduction principle, can utilize power triode output short circuit rapid heating up and give self recovery fuse element with heat synchronous conduction, make self recovery fuse instantaneous action protection.
2. The technical scheme is as follows:
a reliable self-recovery power output over-current protection device comprises an over-current protection circuit; the method is characterized in that: the overcurrent protection circuit comprises triodes T1 and T2 and a self-resetting fuse R47; the overcurrent protection circuit specifically comprises: the E pole of the triode T1 is connected with the direct current output power supply, the resistor R11 and the resistor R12 are connected with the direct current output power supply in parallel, and after being connected in parallel, the resistor R10 is connected in series and then connected with the B pole of the triode T1; the C pole of the triode T1 is connected with one end of a resistor R8, and the other end of the resistor R8 is the output negative pole of the power supply; one end of the resistor R9 is connected with the C pole of the triode T1, and the other end of the resistor R9 is connected with the B pole of the triode T2; the C electrode of the T2 of the triode is connected with one end of a self-recovery fuse R47; the other end of the self-reset fuse R47 is the output anode of the power supply; the gas discharge tube is connected in parallel between the output anode of the power supply and the output cathode of the power supply; the transistor T2 and the resistor R47 are tightly arranged and welded on the large pad which is fully coated with soldering tin.
Further, the dc output power is 12V.
Further, the self-resetting fuse R47 is of type SCF 020-1812.
3. Has the advantages that:
in the utility model, the power triode T2 of the constant current output circuit and the self-resetting fuse R47 are tightly arranged and welded on the same large pad fully coated with the soldering tin, on one hand, because the output circuit part forms the constant current output circuit, namely no matter how the external load changes, the output current of the host machine through the port can be always limited within a rated range; in another aspect; once the power output has short-circuit fault, the high temperature generated by the power triode T2 makes the self-reset fuse R47 synchronously heat through the heat conducting area, and the self-reset fuse is prompted to instantaneously act to cut off the external short-circuit load, so that the power output short-circuit protection effect is achieved.
Drawings
FIG. 1 is a circuit diagram of the prior art;
fig. 2 is a circuit diagram of the present invention.
Detailed Description
As shown in fig. 2 and 3, a reliable self-recovery power output over-current protection device comprises an over-current protection circuit; the method is characterized in that: the overcurrent protection circuit comprises triodes T1 and T2 and a self-resetting fuse R47; the overcurrent protection circuit specifically comprises: the E pole of the triode T1 is connected with the direct current output power supply, the resistor R11 and the resistor R12 are connected with the direct current output power supply in parallel, and after being connected in parallel, the resistor R10 is connected in series and then connected with the B pole of the triode T1; the C pole of the triode T1 is connected with one end of a resistor R8, and the other end of the resistor R8 is the output negative pole of the power supply; one end of the resistor R9 is connected with the C pole of the triode T1, and the other end of the resistor R9 is connected with the B pole of the triode T2; the C electrode of the T2 of the triode is connected with one end of a self-recovery fuse R47; the other end of the self-reset fuse R47 is the output anode of the power supply; the gas discharge tube is connected in parallel between the output anode of the power supply and the output cathode of the power supply; the transistor T2 and the resistor R47 are tightly arranged and welded on the large pad which is fully coated with soldering tin.
The device can accurately control the maximum output limiting current by adjusting the resistance values of the current limiting resistors R11 and R12; the triodes T2 and the resistor R47 are tightly welded on the same large welding disc which is fully coated with soldering tin, the effect of quickly cutting off an external load is achieved through the negative temperature coefficient impedance characteristic of the self-recovery fuse, and the gas discharge tube which is connected in parallel with the output terminal can effectively filter various surge high voltages introduced by the output terminal and protect an internal circuit from being broken down by high voltage.
Further, the dc output power is 12V.
Further, the self-resetting fuse R47 is of type SCF 020-1812.
The external power supply and the internal working power supply of the host are completely isolated by the protection circuit, the phenomenon that the complete machine cannot normally work due to the failure of the power supply inside the host caused by external damage in any form can be avoided, and the main idea of the design is to prevent the host from realizing a normal alarm function caused by the short circuit of illegal molecules through a circuit (such as a keyboard or a detector circuit) outside the host.
The device adopts a constant current source output circuit scheme consisting of 7 components such as a power triode and the like, and realizes high-precision reliable current limiting of the output of the auxiliary power supply of the host. The current-limiting peak value of the power output is determined by the constant current source circuit, and the current-limiting protection action current of the self-recovery fuse is far larger than the current-limiting peak value of the power, so that the current-limiting protection action current of the self-recovery fuse is not lower than 2 times of the current-limiting peak value of the constant current source, the maximum rated current of the power output in practical application is 800 milliamperes, and the specification of the current-limiting protection action current of the self-recovery fuse is 2 amperes.
In practice, the transistor T2 and the resistor R47 are welded on a square bonding pad in the figure; if an external circuit connected with the output of the auxiliary power supply is short-circuited, the protection circuit enters an output rated current protection state, at the moment, the power triode T2 rapidly heats due to output short circuit, and because the power triode T2 and the self-resetting fuse R47 are arranged in the same heat conduction area, the self-resetting fuse synchronously heats due to heat conduction, the impedance of the self-resetting fuse is rapidly increased to infinity within 1-2 seconds, so that the power supply short-circuit output is cut off, and the effect of protecting an internal circuit from being burnt is achieved. Once the short circuit of the external output is recovered, the output of the auxiliary power supply of the host can still work normally.
Although the present invention has been described with reference to the preferred embodiments, it should be understood that various changes and modifications can be made therein by those skilled in the art without departing from the spirit and scope of the invention as defined by the appended claims.
Claims (3)
1. A reliable self-recovery power output over-current protection device comprises an over-current protection circuit; the method is characterized in that: the overcurrent protection circuit comprises a triode T1 and a triode T2; the overcurrent protection circuit specifically comprises: the E pole of the triode T1 is connected with the direct current output power supply, the resistor R11 and the resistor R12 are connected with the direct current output power supply in parallel, and after being connected in parallel, the resistor R10 is connected in series and then connected with the B pole of the triode T1; the C pole of the triode T1 is connected with one end of a resistor R8, and the other end of the resistor R8 is the output negative pole of the power supply; one end of the resistor R9 is connected with the C pole of the triode T1, and the other end of the resistor R9 is connected with the B pole of the triode T2; the C electrode of the T2 of the triode is connected with one end of a self-recovery fuse R47; the other end of the self-reset fuse R47 is the output anode of the power supply; the gas discharge tube is connected in parallel between the output anode of the power supply and the output cathode of the power supply;
the transistor T2 and the resistor R47 are tightly arranged and welded on the large pad which is fully coated with soldering tin.
2. A reliable self-healing power supply output over-current protection device as claimed in claim 1, wherein: the DC output power supply is 12V.
3. A reliable self-healing power supply output over-current protection device as claimed in claim 1, wherein: the self-resetting fuse R47 is of type SCF 020-1812.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202021074002.2U CN212183096U (en) | 2020-06-12 | 2020-06-12 | Reliable self-recovery power output overcurrent protection device |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202021074002.2U CN212183096U (en) | 2020-06-12 | 2020-06-12 | Reliable self-recovery power output overcurrent protection device |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CN212183096U true CN212183096U (en) | 2020-12-18 |
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Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN202021074002.2U Expired - Fee Related CN212183096U (en) | 2020-06-12 | 2020-06-12 | Reliable self-recovery power output overcurrent protection device |
Country Status (1)
| Country | Link |
|---|---|
| CN (1) | CN212183096U (en) |
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2020
- 2020-06-12 CN CN202021074002.2U patent/CN212183096U/en not_active Expired - Fee Related
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| Date | Code | Title | Description |
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| GR01 | Patent grant | ||
| GR01 | Patent grant | ||
| CF01 | Termination of patent right due to non-payment of annual fee | ||
| CF01 | Termination of patent right due to non-payment of annual fee |
Granted publication date: 20201218 |