Detection circuit for preventing complete equipment from overheating

Abstract

The utility model relates to the technical field of overheating detection, in particular to a detection circuit for preventing complete equipment from overheating. Comprising a thermistor used for sampling equipment temperature signals in real time, a differential amplification circuit used for converting the temperature signals into voltage signals, a signal processing circuit and a signal output circuit used for outputting action signals or alarm signals. A temperature signal of a measured part of equipment is sampled in real time through a thermistor, and the temperature signal is converted into a voltage signal through a differential amplification circuit; the voltage detection circuit is used for detecting a voltage signal, transmitting the voltage signal to the signal processing circuit, comparing the detected voltage signal data with a set threshold value, and outputting a corresponding instruction to the signal output circuit; when the starting threshold value is reached, the signal output circuit outputs a corresponding action signal or an alarm signal; the operation and maintenance personnel receive the alarm signal, so that the operation and maintenance personnel can maintain the equipment conveniently, and meanwhile, damage and power failure accidents caused by overheating of devices in the equipment are reduced; the device is simple in structure and low in manufacturing cost.

Description

Technical Field

[0001] The utility model relates to the technical field of overheat detection, in particular to a detection circuit for preventing a complete set of equipment from overheating. Background Art

[0002] In complete sets of equipment such as power distribution and energy storage, various components need to be connected with copper busbars or cables to form a complete power circuit to achieve the purpose of power transmission and control. The power circuit is composed of the connection between copper busbars, cables and devices. These conductors or devices have natural resistance, and there is natural contact resistance at the connection between the devices and copper busbars and cables. In the working state, these circuits will pass current, so the power circuit will naturally generate heat during operation.

[0003] Normally, when the cables, copper busbars and components are connected reliably, the loop resistance is the line resistance plus a small contact resistance; the resistance heat is also within the tolerable range;

[0004] When the connection is unreliable, for example, a loose connection or a screw that is not fully tightened, the small contact resistance will become very large, which will generate a lot of extra heat. This extra heat cannot be dissipated, causing the temperature of the loose connection to rise until the temperature exceeds the maximum tolerance temperature of the device or conductor, and eventually burns out.

[0005] This condition will not only cause thermal damage to the device, but also cause serious power outages; therefore, in engineering applications, this condition must be avoided.

[0006] More seriously, in equipment production, once an unreliable connection occurs, since these connection parts are generally located inside the cabinet, it is difficult to be discovered during subsequent inspections, and the only thing left is to passively wait for the accident to occur. Therefore, there is an urgent need to invent a detection circuit to prevent the complete set of equipment from overheating. Utility Model Content

[0007] The utility model aims to solve the defects and shortcomings of the prior art and provides a detection circuit for preventing overheating of a complete set of equipment, which can avoid damage to components in the equipment due to excessive temperature.

[0008] To achieve the above-mentioned purpose, the technical solution adopted by the present invention is a detection circuit for preventing a complete set of equipment from overheating, comprising a thermistor for real-time sampling of a temperature signal of the equipment, a differential amplifier circuit for converting the temperature signal into a voltage signal, a signal processing circuit, a signal output circuit for outputting an action signal or an alarm signal, a first resistor, a second resistor, a first capacitor and a second capacitor; the thermistor is installed on the equipment to be detected, the first capacitor, the second capacitor and the thermistor are connected in parallel, one end of which is electrically connected to the input end of the differential amplifier circuit and the other end is grounded, one end of the first resistor is connected to VCC and the other end is electrically connected to the first capacitor; one end of the second resistor is electrically connected to the second capacitor and the other end is electrically connected to the thermistor, the output end of the differential amplifier circuit is electrically connected to the input end of the signal processing circuit, and the output end of the signal processing circuit is electrically connected to the signal output circuit.

[0009] Furthermore, the differential amplifier circuit includes a third resistor, a fourth resistor, a fifth resistor, a sixth resistor, a third capacitor, a fourth capacitor and an operational amplifier; the third resistor and the third capacitor are connected in parallel, one end of which is grounded and the other end is electrically connected to the fourth resistor; one end of the fourth resistor is electrically connected to the thermistor and the other end is electrically connected to the non-inverting input of the operational amplifier; one end of the fifth resistor is electrically connected to the thermistor and the other end is electrically connected to the inverting input of the operational amplifier; the sixth resistor and the fourth capacitor are connected in series, one end of which is electrically connected to the inverting input of the operational amplifier and the other end is electrically connected to the output of the operational amplifier.

[0010] Furthermore, the signal processing circuit includes a digital signal processor, a transistor, a MOS transistor, a seventh resistor, an eighth resistor, a ninth resistor and a power relay; the input pin of the digital signal processor is electrically connected to the output end of the operational amplifier, the output pin of the digital signal processor is electrically connected to the base of the transistor, one end of the seventh resistor is connected to a 24V voltage, the other end is electrically connected to the collector of the transistor, and the emitter of the transistor is grounded; one end of the eighth resistor is electrically connected to the gate of the MOS transistor, the source of the MOS transistor is connected to a 24V voltage, one end of the ninth resistor is grounded, and the other end is electrically connected to the drain of the MOS transistor, and the power relay is electrically connected to both ends of the ninth resistor.

[0011] Furthermore, the signal output circuit is an audible and visual alarm or a circuit breaker tripping relay.

[0012] Beneficial effects of the utility model:

[0013] The utility model provides a detection circuit for preventing a complete set of equipment from overheating. The circuit samples the temperature signal of the measured part of the equipment in real time through a thermistor, and converts the temperature signal into a voltage signal through a differential amplifier circuit; the voltage signal is transmitted to a signal processing circuit, and then the detected voltage signal data is compared with a set threshold value, and a corresponding instruction is output to a signal output circuit; when the starting threshold value is reached, the signal output circuit outputs a corresponding action signal or an alarm signal; the operation and maintenance personnel receive the alarm signal, which is convenient for the operation and maintenance personnel to maintain the equipment, while reducing damage to the components in the equipment and power outage accidents due to overheating; the present application is not only simple in structure but also low in manufacturing cost. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] Figure 1 The utility model is a circuit principle diagram of a detection circuit for preventing a complete set of equipment from overheating. DETAILED DESCRIPTION

[0015] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the embodiments described are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0016] It should be noted that all directional indications (such as up, down, left, right, front, back, etc.) in the embodiments of the present invention are only used to explain the relative position relationship, movement status, etc. between the various components under a certain specific posture (as shown in the accompanying drawings). If the specific posture changes, the directional indication will also change accordingly.

[0017] In addition, the descriptions of "first," "second," etc. in this utility model are for descriptive purposes only and should not be understood as indicating or implying their relative importance or implicitly indicating the number of the technical features indicated. Therefore, the features defined as "first" or "second" may explicitly or implicitly include at least one of such features. In addition, the technical solutions between the various embodiments can be combined with each other, but this must be based on the fact that they can be implemented by ordinary technicians in this field. When the combination of technical solutions is contradictory or cannot be implemented, it should be deemed that such combination of technical solutions does not exist and is not within the scope of protection required by this utility model.

[0018] The utility model provides a detection circuit for preventing a complete set of equipment from overheating.

[0019] In the embodiment of the present utility model, Figure 1As shown, a detection circuit for preventing a complete set of equipment from overheating includes a thermistor for real-time sampling of a temperature signal of the equipment, a differential amplifier circuit for converting the temperature signal into a voltage signal, a signal processing circuit, a signal output circuit for outputting an action signal or an alarm signal, a first resistor, a second resistor, a first capacitor, and a second capacitor; the thermistor is installed on the equipment to be detected, the first capacitor, the second capacitor, and the thermistor are connected in parallel, one end of which is electrically connected to the input end of the differential amplifier circuit and the other end is grounded, one end of the first resistor is connected to VCC, and the other end is electrically connected to the first capacitor; one end of the second resistor is electrically connected to the second capacitor, and the other end is electrically connected to the thermistor, the output end of the differential amplifier circuit is electrically connected to the input end of the signal processing circuit, and the output end of the signal processing circuit is electrically connected to the signal output circuit.

[0020] In this embodiment, the differential amplifier circuit includes a third resistor, a fourth resistor, a fifth resistor, a sixth resistor, a third capacitor, a fourth capacitor and an operational amplifier; the third resistor and the third capacitor are connected in parallel, one end of which is grounded and the other end is electrically connected to the fourth resistor; one end of the fourth resistor is electrically connected to the thermistor and the other end is electrically connected to the non-inverting input of the operational amplifier; one end of the fifth resistor is electrically connected to the thermistor and the other end is electrically connected to the inverting input of the operational amplifier; the sixth resistor and the fourth capacitor are connected in series, one end of which is electrically connected to the inverting input of the operational amplifier and the other end is electrically connected to the output of the operational amplifier.

[0021] In this embodiment, the signal processing circuit includes a digital signal processor, a transistor, a MOS transistor, a seventh resistor, an eighth resistor, a ninth resistor, and a power relay; an input pin of the digital signal processor is electrically connected to the output end of the operational amplifier, an output pin of the digital signal processor is electrically connected to the base of the transistor, one end of the seventh resistor is connected to a 24V voltage, the other end is electrically connected to the collector of the transistor, and the emitter of the transistor is grounded; one end of the eighth resistor is electrically connected to the gate of the MOS transistor, the source of the MOS transistor is connected to a 24V voltage, one end of the ninth resistor is grounded, and the other end is electrically connected to the drain of the MOS transistor, and the power relay is electrically connected to both ends of the ninth resistor.

[0022] In this embodiment, the signal output circuit is an audible and visual alarm or a circuit breaker tripping relay.

[0023] Specifically, the MOS tube in this application is a P-channel MOS tube; the type of the transistor is NPN.

[0024] Specifically, the present application is provided with a reset button, which is electrically connected to the signal processing circuit. The temperature signal of the measured part of the equipment is sampled in real time through a thermistor, and the temperature signal is converted into a voltage signal through a differential amplifier circuit; the voltage signal is transmitted to the signal processing circuit, and then the detected voltage signal data is compared with the set threshold, and the corresponding instruction is output to the signal output circuit; when the start threshold is reached, the signal output circuit outputs a corresponding action signal or alarm signal; the operation and maintenance personnel receive the alarm signal and immediately perform fault processing. After completion, the reset button is used to reset, thereby restarting the detection.

[0025] Thermistors are installed at locations where equipment needs to be tested, usually at circuit breaker outlets, copper busbar joints, and other locations where problems are more likely to occur. The resistance of thermistors changes linearly with temperature. According to the series voltage division principle, different resistance values ​​will generate different voltage signals. This voltage signal passes through a differential amplifier circuit, which processes the initial voltage signal into a voltage signal within a specified range, and then inputs the voltage signal into a signal processing circuit.

[0026] Thermistors and differential amplifier circuits can be set up in multiple channels according to actual needs to meet the detection needs of different configurations; for the sampled parts, it is necessary to determine their maximum operating temperature based on their temperature rise limit; for copper busbars and switch devices, according to national standards, their temperature rise requirements do not exceed 70K, and the maximum ambient temperature is 40°C; therefore, the maximum operating temperature of copper busbars and switch devices should not exceed 110°C; at the same time, considering the influence of some error factors, this application sets the temperature threshold to 150°C; in this way, it can play a role in temperature protection and prevent malfunctions caused by parameter settings being too small. Then, according to the temperature-resistance table of the thermistor, the resistance value at 150°C is obtained; then, based on this resistance value, it is brought into the differential amplifier circuit to obtain the thermistor's voltage divider Vpn;

[0027] Because the digital signal processor DSP has requirements for the amplitude of the input voltage signal, the gain of the operational amplifier is adjusted by adjusting the resistance values ​​of the fourth resistor Ra, the third resistor Rb, the fourth resistor Rc, and the fifth resistor Rd; that is,

[0028] Vo=AVpn; wherein A is the operational amplifier gain, and A is related to the fourth resistor Ra, the third resistor Rb, the fourth resistor Rc, and the fifth resistor Rd; so that the amplitude of the output voltage signal Vo meets the input voltage requirement of the digital signal processor DSP.

[0029] Set the judgment threshold of the digital signal processor (DSP) as Vo’ = Vpn(150), that is, the output voltage signal of the thermistor and the differential amplifier circuit loop at 150°C. The digital signal processor (DSP) receives the input sampled voltage signal and compares this voltage signal with the set threshold Vo’ (converting the threshold temperature into the corresponding voltage) in real time. The voltage signal Vo output by the differential amplifier circuit enters the digital signal processor (DSP). The digital signal processor (DSP) judges this voltage signal according to the program burned into the root.

[0030] When Vo > Vo’, it indicates that the actual temperature is higher than 150°C. The output pin OUT of the digital signal processor (DSP) outputs a high level, triggering the triode, then triggering the high-power MOS transistor, and then triggering the power relay to close, outputting one or more closed dry contact signals.

[0031] When Vo < Vo’, it indicates that the actual temperature is lower than 150°C. The output pin OUT of the digital signal processor (DSP) outputs a low level, not triggering the triode, nor triggering the high-power MOS transistor, and thus not triggering the relay to close, outputting one or more open dry contact signals.

[0032] The signal output circuit executes corresponding actions according to the instructions output by the signal processing, such as outputting normally closed dry contact signals or normally open dry contact signals. The output dry contact signals act on the circuit breaker tripping or sound and light alarms, etc.

[0033] The digital signal processor (DSP) makes a logical judgment on this voltage signal according to the preset program. When exceeding the threshold, it outputs a weak voltage signal, and through the peripheral circuit, drives the high-power switching device MOS transistor to conduct. The MOS transistor then drives the power relay, and finally outputs the corresponding dry contact signal, thus achieving the ultimate control and alarm purposes. At the same time, by reasonably connecting the relay and the MOS transistor, more flexible and efficient circuit control can be achieved.

[0034] This application can effectively avoid device damage and power outage accidents caused by unreliable connections of copper bars and switches due to human error operations. At the same time, it can also configure multiple-channel temperature sampling and multiple-channel dry contact outputs according to actual needs, with strong scalability.

[0035] The above are only the preferred embodiments of the present utility model, and do not limit the patent scope of the present utility model. Any equivalent structural transformation made under the inventive concept of the present utility model by using the content of the specification and drawings of the present utility model, or directly / indirectly applied in other related technical fields, is included in the patent protection scope of the present utility model.

Claims

1. A detection circuit for preventing a complete set of equipment from overheating, characterized in that: The device comprises a thermistor for real-time sampling of a device temperature signal, a differential amplifier circuit for converting the temperature signal into a voltage signal, a signal processing circuit, a signal output circuit for outputting an action signal or an alarm signal, a first resistor, a second resistor, a first capacitor, and a second capacitor; the thermistor is mounted on the device to be detected, the first capacitor, the second capacitor, and the thermistor are connected in parallel, one end of the thermistor is electrically connected to the input end of the differential amplifier circuit, and the other end is grounded; one end of the first resistor is connected to VCC, and the other end is electrically connected to the first capacitor; one end of the second resistor is electrically connected to the second capacitor, and the other end is electrically connected to the thermistor; the output end of the differential amplifier circuit is electrically connected to the input end of the signal processing circuit, and the output end of the signal processing circuit is electrically connected to the signal output circuit.

2. The detection circuit for preventing overheating of a complete set of equipment according to claim 1, characterized in that: The differential amplifier circuit includes a third resistor, a fourth resistor, a fifth resistor, a sixth resistor, a third capacitor, a fourth capacitor and an operational amplifier; the third resistor and the third capacitor are connected in parallel, one end of which is grounded and the other end is electrically connected to the fourth resistor; one end of the fourth resistor is electrically connected to the thermistor and the other end is electrically connected to the non-inverting input of the operational amplifier; one end of the fifth resistor is electrically connected to the thermistor and the other end is electrically connected to the inverting input of the operational amplifier; the sixth resistor and the fourth capacitor are connected in series, one end of which is electrically connected to the inverting input of the operational amplifier and the other end is electrically connected to the output of the operational amplifier.

3. The detection circuit for preventing overheating of a complete set of equipment according to claim 2, characterized in that: The signal processing circuit includes a digital signal processor, a transistor, a MOS transistor, a seventh resistor, an eighth resistor, a ninth resistor and a power relay; the input pin of the digital signal processor is electrically connected to the output end of the operational amplifier, the output pin of the digital signal processor is electrically connected to the base of the transistor, one end of the seventh resistor is connected to a 24V voltage, the other end is electrically connected to the collector of the transistor, and the emitter of the transistor is grounded; one end of the eighth resistor is electrically connected to the gate of the MOS transistor, and the source of the MOS transistor is connected to a 24V voltage; one end of the ninth resistor is grounded, and the other end is electrically connected to the drain of the MOS transistor; the power relay is electrically connected to both ends of the ninth resistor.

4. The detection circuit for preventing overheating of a complete set of equipment according to claim 1, characterized in that: The signal output circuit is an audible and visual alarm or a circuit breaker tripping relay.

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