Overload protection device

Abstract

The utility model relates to the technical field of overload protection, and discloses an overload protection device which comprises a sampling unit, a comparison unit and a tripping unit, the input end of the sampling unit inputs current signals of a power supply loop of equipment to be protected, the output end of the sampling unit is connected with the input end of the comparison unit, the sampling unit is arranged in a heat preservation container, and the tripping unit is arranged in the heat preservation container. The sampling unit is used for outputting sampling voltage after heating the interior of the insulated container based on the current signal; the output end of the comparison unit is connected with the control end of the tripping unit, and the comparison unit is used for outputting a tripping signal when the sampling voltage is greater than the internal threshold voltage; and the output end of the tripping unit is connected with the control end of the to-be-protected equipment, and the tripping unit is used for cutting off a power supply loop of the to-be-protected equipment based on the tripping signal. According to the utility model, overload protection is carried out in a mode of converting an overcurrent signal into a heat signal, interference of environment temperature on the heat signal is avoided by using the heat preservation container, and the reliability of overload protection is improved.

Description

TECHNICAL FIELD

[0001] The utility model relates to overload protection technical field, concretely relates to an overload protection device. BACKGROUND

[0002] The existing circuit breaker overload protection is generally driven by the heating of the current-carrying member of different materials to drive the bimetallic strip to bend and push the traction rod to drive the jump buckle to trip, when the overload protection is carried out by using the bimetallic strip, the metal sheet is greatly affected by the environmental temperature, and the overload threshold is low due to the high environmental temperature, thereby causing the overload protection to be not timely, and the product debugging is complicated, and the consistency is poor; and when the existing electronic circuit breaker samples by using the mutual inductor, the bandwidth and the anti-interference of the digital circuit are affected, and the overload protection precision is low. SUMMARY

[0003] Therefore, the utility model provides an overload protection device to solve the problem of poor reliability of the overload protection device caused by the change of the environmental temperature.

[0004] The utility model provides an overload protection device, it includes: sampling unit, comparison unit and tripping unit, wherein, the input end of sampling unit inputs the current signal of the power supply loop of the device to be protected, the output end of sampling unit is connected with the input end of comparison unit, sampling unit sets up in the heat preservation container, and sampling unit is used for outputting sampling voltage based on the heating of the inside of heat preservation container to current signal, the output end of comparison unit is connected with the control end of tripping unit, and comparison unit is used for outputting tripping signal when sampling voltage is greater than internal threshold voltage, the output end of tripping unit is connected with the control end of the device to be protected, and tripping unit is used for cutting off the power supply loop of the device to be protected based on tripping signal.

[0005] The overload protection device provided by the utility model can heat the inside of the heat preservation container according to the size of the current signal of the device to be protected, and can output the sampling voltage of corresponding size according to the temperature inside the heat preservation container, so that the heat exchange between the inside and outside of the container can be avoided by using the heat preservation container, the size of the output sampling voltage is only related to the current size of the device to be protected, is not affected by the external environmental temperature, the anti-interference of the overload protection is improved, and the reliability of the overload protection is improved by converting the overcurrent signal into a heat signal.

[0006] In an alternative embodiment, the sampling unit comprises a heating unit and a heat receiving unit, wherein the input end of the heating unit inputs the current signal of the power supply loop of the device to be protected, and the heating unit is used to generate heat based on the current signal and heat the inside of the heat preservation container; the output end of the heat receiving unit is connected with the input end of the comparison unit, and the heat receiving unit is used to output the sampling voltage after adjusting the internal resistance based on the temperature inside the heat preservation container.

[0007] The overload protection device provided by the utility model, the heat unit is used for heating the inside of the heat preservation container based on the heat generated by the current signal, the heat preservation container can reduce heat loss to the maximum extent, the heat receiving unit can collect accurate temperature signals without being affected by external environment temperature, and the reliability and accuracy of the overload protection of the device are improved.

[0008] In an alternative embodiment, the heat receiving unit comprises a first thermistor, wherein a first end of the first thermistor is grounded, and a second end of the first thermistor is connected with an input end of the comparison unit.

[0009] In an alternative embodiment, the overload protection device further comprises at least one current transformer, wherein an input end of each current transformer respectively inputs a current signal of one phase power supply circuit of the equipment to be protected, and an output end of each current transformer is connected with an input end of the heat unit.

[0010] In an alternative embodiment, the heat unit comprises at least one heating resistor, wherein each heating resistor is connected in parallel with an output end of one current transformer.

[0011] The overload protection device provided by the utility model can separately collect the current of each phase power supply circuit by each current transformer, can make the corresponding heating resistor heat up when the current of any phase is overloaded, and thus triggers the overload protection, thereby improving the reliability of the device.

[0012] In an alternative embodiment, the comparison unit comprises a voltage comparison circuit and a reference voltage generation circuit, wherein a first input end of the voltage comparison circuit is connected with an output end of the sampling unit, a second input end of the voltage comparison circuit is connected with an output end of the reference voltage generation circuit, a first end of the voltage comparison circuit is connected with a first end of the reference voltage generation circuit and an external power supply, and an output end of the voltage comparison circuit is connected with a second end of the reference voltage generation circuit and a control end of the tripping unit.

[0013] In an alternative embodiment, the voltage comparison circuit comprises a comparator, a first resistor and a second resistor, wherein a reverse input end of the comparator is connected with a first end of the first resistor, a first end of the second resistor and an output end of the sampling unit, a forward input end of the comparator is connected with an output end of the reference voltage generation circuit, an output end of the comparator is connected with a control end of the tripping unit, a second end of the first resistor is grounded, and a second end of the second resistor is connected with a first end of the reference voltage generation circuit.

[0014] In an alternative embodiment, the reference voltage generating circuit comprises a third resistor, a fourth resistor, a fifth resistor and a second thermistor, wherein a first end of the third resistor is connected with a second end of the fourth resistor, a second end of the third resistor is connected with a first end of the fourth resistor, a first end of the second thermistor, a first end of the fifth resistor and a positive input end of the comparator; a second end of the fourth resistor is connected with a second end of the second thermistor and grounded; a second end of the fifth resistor is connected with an output end of the comparator.

[0015] In an alternative embodiment, the tripping unit comprises a current limiting circuit, a filter circuit and a tripping circuit, wherein a first end of the current limiting circuit is connected with an output end of the comparison unit, a second end of the current limiting circuit is connected with a first end of the filter circuit and a control end of the tripping circuit; a second end of the filter circuit is connected with a first end of the tripping circuit and grounded; a second end of the tripping circuit is connected with a control end of the device to be protected.

[0016] In an alternative embodiment, the tripping circuit comprises a driving switch and a tripper, wherein a control end of the driving switch is connected with a second end of the current limiting circuit, a first end of the driving switch is connected with a second end of the filter circuit, a third end of the driving switch is connected with a first end of the tripper; a second end of the tripper is connected with a control end of the device to be protected. BRIEF DESCRIPTION OF DRAWINGS

[0017] In order to more clearly illustrate the embodiments of the present application or the technical solutions in the prior art, the following will briefly introduce the drawings needed in the description of the embodiments or the prior art. Obviously, the drawings described below are some embodiments of the present application, and other drawings can also be obtained by those skilled in the art without creative labor.

[0018] Figure 1 is a component diagram of the overload protection device according to an embodiment of the present application;

[0019] Figure 2 is a component diagram of the sampling unit according to an embodiment of the present application;

[0020] Figure 3 is another component diagram of the overload protection device according to an embodiment of the present application;

[0021] Figure 4 is a specific circuit structure diagram of the overload protection device according to an embodiment of the present application;

[0022] Figure 5 is another specific circuit structure diagram of the overload protection device according to an embodiment of the present application. DETAILED DESCRIPTION

[0023] In order to make the purpose, technical scheme and advantages of the embodiments of the present application clearer, the technical scheme of the embodiments of the present application will be described clearly and completely below in combination with the drawings in the embodiments of the present application. Obviously, the described embodiments are some of the embodiments of the present application, rather than all the embodiments of the present application. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative labor fall within the scope of protection of the present application.

[0024] In the description of the present application, it should be noted that the orientations or positional relationships indicated by the terms "center", "upper", "lower", "left", "right", "vertical", "horizontal", "inner", "outer", etc. are based on the orientations or positional relationships shown in the drawings, and are only for the convenience of describing the present application and simplifying the description, and therefore cannot be understood as indicating or implying that the devices or elements referred to must have a particular orientation, be constructed and operated in a particular orientation, and therefore cannot be understood as limiting the present application. In addition, the terms "first", "second", "third" are only for the purpose of description, and cannot be understood as indicating or implying relative importance.

[0025] In the description of the present application, it should be noted that unless otherwise explicitly specified and limited, the terms "mounting", "connection", "connection" should be understood broadly, for example, it can be fixedly connected, or it can be detachably connected, or integrally connected; it can be mechanically connected, or it can be electrically connected; it can be directly connected, or it can be indirectly connected through an intermediate medium; it can be the communication between two elements, or it can be wireless connection, or it can be wired connection. For those skilled in the art, the specific meaning of the above terms in the present application can be understood according to the specific circumstances.

[0026] In addition, the technical features involved in the different embodiments of the present application described below can be combined with each other as long as there is no conflict.

[0027] The existing overload protection device usually drives the bimetallic strip to bend by heating the current-carrying member itself, pushes the traction rod to drive the trip unit to trip, and the metal sheet is easily affected by the surrounding temperature, which leads to delayed overload protection response or false triggering of overload protection, and the heating of the metal sheet increases the overall temperature rise of the overload protection device, which reduces the service life of the overload protection device.

[0028] Therefore, the present embodiment provides an overload protection device, as shown in the figure, comprising: a sampling unit 1, a comparison unit 2 and a tripping unit 3. Figure 1

[0029] Figure 1 ​In the specific implementation, the input end of the sampling unit 1 inputs a current signal of a power supply circuit of the device to be protected, the output end of the sampling unit 1 is connected with the input end of the comparison unit 2, the sampling unit 1 is arranged in the heat preservation container, and the sampling unit 1 is configured to output a sampling voltage based on the current signal after heating the inside of the heat preservation container.

[0030] In particular, Figure 1 In the specific implementation, the sampling unit 1 collects a current signal in a power supply circuit of the device to be protected, and when the current size changes, the sampling unit 1 can release different amounts of heat to heat the inside of the heat preservation container according to different current sizes. The heat preservation container collects all the heat released by the sampling unit 1, and maximally preserves heat to avoid heat exchange between the inside and the outside. As the temperature in the heat preservation container gradually rises, the internal resistance of the sampling unit 1 changes, and thus the size of the sampling voltage output by the sampling unit 1 changes.

[0031] Optionally, to make the heat in the heat preservation container uniform, the heat preservation container can be a metal heat preservation box.

[0032] Optionally, the sampling unit can include a resistance for heating and a temperature-sensitive resistance capable of changing resistance according to the surrounding temperature.

[0033] Figure 1 In the specific implementation, the output end of the comparison unit 2 is connected with the control end of the tripping unit 3, and the comparison unit 2 is configured to output a tripping signal when the sampling voltage is greater than the internal threshold voltage.

[0034] Figure 1 In the specific implementation, the output end of the tripping unit 3 is connected with the control end of the device to be protected, and the tripping unit 3 is configured to cut off the power supply circuit of the device to be protected based on the tripping signal.

[0035] In particular, Figure 1 In the specific implementation, when the comparison unit 2 determines that the sampling voltage is greater than the internal threshold voltage, the comparison unit 2 outputs a tripping signal to cut off the power supply of the device to be protected; and when the comparison unit 2 determines that the sampling voltage is less than or equal to the internal threshold voltage, the comparison unit 2 does not output a tripping signal.

[0036] The overload protection device provided in the embodiment can generate corresponding heat to heat the inside of the heat preservation container according to the size of the current signal of the device to be protected, can output a sampling voltage of a corresponding size according to the temperature in the inside of the heat preservation container, can avoid heat exchange between the inside and the outside of the container by using the heat preservation container, can make the size of the output sampling voltage only related to the current size of the device to be protected and not affected by the external environment temperature, can improve the anti-interference performance of the overload protection, and can improve the reliability of the overload protection by using the way of converting the overcurrent signal into a heat signal.

[0037] In some optional implementations, as Figure 2As shown, the sampling unit 1 comprises a heating unit 11 and a heat receiving unit 12, wherein the input end of the heating unit 11 inputs the current signal of the power supply circuit of the device to be protected, and the heating unit 11 is used to generate heat based on the current signal and heat the inside of the heat preservation container; the output end of the heat receiving unit 12 is connected with the input end of the comparison unit 2, and the heat receiving unit 12 is used to output the sampling voltage after adjusting the internal resistance based on the temperature of the inside of the heat preservation container.

[0038] Specifically, Figure 2 In the heating unit 11, the heat generated based on the current signal is used to heat the inside of the heat preservation container, and the heat preservation container can reduce heat loss to the maximum extent, so that the heat receiving unit can collect accurate temperature signals without being affected by the external environment temperature.

[0039] Optionally, Figure 2 In the heating unit 11, any device capable of generating different heat according to the size of the current flowing through can be selected, for example, a resistor with a large internal resistance. The heat receiving unit 12 can comprise a first thermistor, which can change the internal resistance according to the surrounding temperature, so as to change the size of the voltage across, that is, the size of the sampling voltage.

[0040] In some optional embodiments, as Figure 3 As shown, the overload protection device further comprises at least one current transformer 4, wherein the input end of each current transformer 4 respectively inputs the current signal of one phase power supply circuit of the device to be protected, and the output end of each current transformer 4 is connected with the input end of the heating unit 11.

[0041] Specifically, Figure 3 In the heating unit 11, when the power supply circuit of the device to be protected is single-phase or multi-phase, the primary side of each current transformer 4 is respectively nested on one phase power supply circuit, and the secondary side respectively outputs the induced current of the phase to the heating unit 11, so that the heating unit can generate heat based on the current signal of any phase line.

[0042] Specifically, Figure 3 In the heating unit 11, the heating unit 11 comprises at least one heating resistor, wherein each heating resistor is connected in parallel with the output end of one current transformer.

[0043] Exemplarily, Figure 4 In the heating unit 11, taking the A, B and C three-phase power supply circuit of the device to be protected as an example, the primary side of the three current transformers (i.e., L1, L2 and L3) is respectively nested on each phase power supply circuit, and the secondary side is respectively connected in parallel with one heating resistor (i.e., R11, R12 and R13), when the primary side of any current transformer has current flowing through, the secondary side outputs the induced current flowing through the heating resistor connected therewith, so that the heating resistor generates heat based on the current heat effect, and the temperature in the heat preservation container is increased.

[0044] In some optional embodiments, as shown in Figure 5 The comparison unit 2 comprises a voltage comparison circuit 21 and a reference voltage generation circuit 22, wherein the first input end of the voltage comparison circuit 21 is connected with the output end of the sampling unit 1, the second input end of the voltage comparison circuit 21 is connected with the output end of the reference voltage generation circuit 22, the first end of the voltage comparison circuit 21 is connected with the first end of the reference voltage generation circuit 22 and an external power supply, and the output end of the voltage comparison circuit 21 is connected with the second end of the reference voltage generation circuit 22 and the control end of the tripping unit 3.

[0045] Specifically, Figure 5 The voltage comparison circuit 21 comprises a comparator U1B, a first resistor R2 and a second resistor R3, wherein the reverse input end of the comparator U1B is connected with the first end of the first resistor R2, the first end of the second resistor R3 and the output end of the sampling unit 1, the positive input end of the comparator U1B is connected with the output end of the reference voltage generation circuit 22, the output end of the comparator U1B is connected with the control end of the tripping unit 3, the second end of the first resistor R2 is grounded, and the second end of the second resistor R3 is connected with the first end of the reference voltage generation circuit 22.

[0046] Specifically, Figure 5 The reference voltage generation circuit comprises a third resistor R4, a fourth resistor R5, a fifth resistor R6 and a second thermistor RT1, wherein the first end of the third resistor R4 is connected with the second end of the fourth resistor R5, the second end of the third resistor R4 is connected with the first end of the fourth resistor R5, the first end of the second thermistor RT1, the first end of the fifth resistor R6 and the positive input end of the comparator U1B, the second end of the fourth resistor R5 is connected with the second end of the second thermistor RT1 and grounded, and the second end of the fifth resistor R6 is connected with the output end of the comparator U1B.

[0047] Specifically, Figure 5 The first thermistor R1 in the heat receiving unit 12 can reduce the internal resistance as the temperature in the heat preservation container rises, and then reduce the voltage division of the external power supply voltage VCC by the first thermistor R1, so that the voltage at the reverse input end of the comparator U1B is reduced. After the external power supply voltage VCC is divided by the third resistor R4, the fourth resistor R5 and the second thermistor RT1, the voltage at the first end of the fifth resistor R6 is superimposed as a threshold voltage and input to the positive input end of the comparator U1B. When the voltage at the reverse input end of the comparator U1B is reduced to be lower than the threshold voltage, the comparator U1B outputs a high-level tripping signal.

[0048] Specifically, Figure 5In the embodiment, the first thermistor R1 is used for temperature compensation, in a high temperature environment, the resistance of the second thermistor RT1 decreases correspondingly with the ambient temperature, so that the voltage of the positive input end of the comparator U1B decreases, the first thermistor R1 needs to decrease the resistance at a higher temperature, so that the voltage of the negative input end of the comparator U1B is lower than that of the positive input end to meet the overload protection characteristics, and the problem of decreasing of the overload current setting value caused by the increase of the ambient temperature is offset.

[0049] In some optional embodiments, as shown in Figure 5 The tripping unit 3 includes a current limiting circuit 31, a filter circuit 32 and a tripping circuit 33, wherein the first end of the current limiting circuit 31 is connected with the output end of the voltage comparison circuit 21 in the comparison unit, the second end of the current limiting circuit 31 is connected with the first end of the filter circuit 32 and the control end of the tripping circuit 33; the second end of the filter circuit 32 is connected with the first end of the tripping circuit 33 and grounded; the second end of the tripping circuit 33 is connected with the control end (i.e. HV) of the device to be protected.

[0050] Specifically, Figure 5 In the embodiment, the current limiting circuit 31 includes a resistor R7, the filter circuit 32 includes an RC filter circuit composed of a resistor R8 and a capacitor C1, and the tripping circuit 33 includes a driving switch Q1 and a tripper K1, wherein the control end of the driving switch Q1 is connected with the second end of the current limiting circuit 31, the first end of the driving switch Q1 is connected with the second end of the filter circuit 32, and the third end of the driving switch Q1 is connected with the first end of the tripper K1; the second end of the tripper K1 is connected with the control end of the device to be protected. The driving switch Q1 can control the tripper K1 to trip based on the high-level tripping signal output by the comparator U1B, so as to cut off the power supply circuit of the device to be protected.

[0051] Although the embodiments of the present application are described in conjunction with the drawings, various modifications and changes can be made by those skilled in the art without departing from the spirit and scope of the present application, and such modifications and changes fall within the scope defined by the appended claims.

Claims

1. An overload protection device, characterized in that The application relates to a temperature protection device for a power supply circuit of a protected device, comprising: a sampling unit, a comparison unit and a tripping unit, wherein, an input end of the sampling unit inputs a current signal of the power supply circuit of the protected device, an output end of the sampling unit is connected with an input end of the comparison unit, the sampling unit is arranged in a heat preservation container, and the sampling unit is used for outputting a sampling voltage after heating the inside of the heat preservation container based on the current signal; an output end of the comparison unit is connected with a control end of the tripping unit, the comparison unit is used for outputting a tripping signal when the sampling voltage is greater than an internal threshold voltage; and an output end of the tripping unit is connected with a control end of the protected device, the tripping unit is used for cutting off the power supply circuit of the protected device based on the tripping signal.

2. The overload protection device of claim 1, wherein The sampling unit comprises a heating unit and a heat receiving unit, wherein, an input end of the heating unit inputs a current signal of the power supply circuit of the protected device, and the heating unit is used for generating heat and heating the inside of the heat preservation container based on the current signal; an output end of the heat receiving unit is connected with an input end of the comparison unit, and the heat receiving unit is used for outputting a sampling voltage after adjusting an internal resistance based on the temperature of the inside of the heat preservation container.

3. An overload protection device according to claim 2, characterised in that The heat receiving unit comprises a first thermistor, wherein, a first end of the first thermistor is grounded, and a second end of the first thermistor is connected with an input end of the comparison unit.

4. The overload protection device of claim 2, wherein Further comprising: at least one current transformer, wherein, an input end of each current transformer respectively inputs a current signal of one phase power supply circuit of the protected device, and an output end of each current transformer is connected with an input end of the heating unit.

5. An overload protection device according to claim 4, characterised in that The heating unit comprises at least one heating resistor, wherein, each heating resistor is connected in parallel with an output end of one current transformer.

6. The overload protection device of claim 1, wherein The comparison unit comprises a voltage comparison circuit and a reference voltage generation circuit, wherein, a first input end of the voltage comparison circuit is connected with an output end of the sampling unit, a second input end of the voltage comparison circuit is connected with an output end of the reference voltage generation circuit, a first end of the voltage comparison circuit is connected with a first end of the reference voltage generation circuit and an external power supply, and an output end of the voltage comparison circuit is connected with a second end of the reference voltage generation circuit and a control end of the tripping unit.

7. An overload protection device according to claim 6, characterised in that The voltage comparison circuit comprises a comparator, a first resistor and a second resistor, wherein, an inverse input end of the comparator is connected with a first end of the first resistor, a first end of the second resistor and an output end of the sampling unit, a forward input end of the comparator is connected with an output end of the reference voltage generation circuit, and an output end of the comparator is connected with a control end of the tripping unit; a second end of the first resistor is grounded; a second end of the second resistor is connected with a first end of the reference voltage generation circuit.

8. An overload protection device according to claim 7, characterised in that The reference voltage generation circuit comprises a third resistor, a fourth resistor, a fifth resistor and a second thermistor, wherein, a first end of the third resistor is connected with a first end of the fourth resistor and a first end of the fifth resistor, a second end of the third resistor is connected with a second end of the fourth resistor and a second end of the fifth resistor, and a second end of the fourth resistor is connected with a second end of the fifth resistor. The first end of the third resistor is connected with the second end of the fourth resistor, and the second end of the third resistor is connected with the first end of the fourth resistor, the first end of the second thermistor, the first end of the fifth resistor and the positive input end of the comparator; The second end of the fourth resistor is connected with the second end of the second thermistor and grounded; The second end of the fifth resistor is connected with the output end of the comparator.

9. The overload protection device of claim 1, wherein, The tripping unit comprises a current limiting circuit, a filter circuit and a tripping circuit, wherein, The first end of the current limiting circuit is connected with the output end of the comparison unit, the second end of the current limiting circuit is connected with the first end of the filter circuit and the control end of the tripping circuit; The second end of the filter circuit is connected with the first end of the tripping circuit and grounded; The second end of the tripping circuit is connected with the control end of the device to be protected.

10. An overload protection device according to claim 9, characterised in that, The tripping circuit comprises a drive switch and a tripper, wherein, The control end of the drive switch is connected with the second end of the current limiting circuit, the first end of the drive switch is connected with the second end of the filter circuit, and the third end of the drive switch is connected with the first end of the tripper; The second end of the tripper is connected with the control end of the device to be protected.

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