Temperature sensor on-line indication circuit

Abstract

The utility model belongs to the electric safety technical field, concretely relates to temperature sensor online indicating circuit. Temperature sensor online indicating circuit, including temperature detection module, comparison voltage setting module and fault discrimination indicating module, temperature detection module and comparison voltage setting module all are connected with fault discrimination indicating module electricity, temperature detection module is used for detecting obtains output voltage U t℃ ; Comparison voltage setting module is used for dividing voltage and obtains comparison voltage U f ; Fault discrimination indicating module is used for discriminating whether temperature sensor is online according to output voltage U t℃ And comparison voltage U f , the utility model has the characteristics that simple structure, save the cost, can the characteristic that whether temperature sensor is online is indicated directly.

Description

Technical Field

[0001] This utility model belongs to the field of electrical safety technology, specifically relating to an online temperature sensor indication circuit. Background Technology

[0002] To ensure electrical safety and prevent electrical fires, multiple conductor temperature sensors are installed in distribution cabinets (boxes). Because equipment malfunctions or excessive current can cause abnormal conductor temperatures, detecting these abnormalities necessitates appropriate protective and early warning alarm measures to prevent fires.

[0003] To improve the reliability of the detection system, it is necessary to determine whether the temperature sensor is reliably connected online. If it is offline or has a disconnection fault, maintenance is required.

[0004] For temperature sensors, since the temperature range is not very large (generally between -20℃ and 125℃), NTC semiconductor temperature sensors with a negative temperature coefficient are typically used. These sensors have low resistance at high temperatures and high resistance at low temperatures. The detection circuit using an NTC sensor generally includes a reference resistor Rs, connected in series with the NTC and a stable voltage applied. The voltage across the temperature sensor resistor Rt or Rs is measured, and the value of the temperature sensor resistor Rt is calculated, allowing the determination of the NTC's temperature. However, general resistance detection circuits tend to saturate the signal when the temperature sensor resistance is high, making it difficult to distinguish whether the temperature sensor is disconnected (offline) or has poor contact. Therefore, the detection device needs to be improved to determine whether the temperature sensor is online. Utility Model Content

[0005] This invention aims to overcome the problem that existing temperature sensor detection circuits are unable to accurately determine whether a temperature sensor is online or has a broken wire. It provides a temperature sensor online indicator circuit that is simple in structure, cost-effective, and can intuitively indicate whether a temperature sensor is online.

[0006] To achieve the above-mentioned objectives, this utility model adopts the following technical solution: The online temperature sensor indication circuit includes a temperature detection module, a comparison voltage setting module, and a fault diagnosis indication module; the temperature detection module and the comparison voltage setting module are both electrically connected to the fault diagnosis indication module. The temperature detection module is used to detect and obtain the output voltage U. t℃ ; The comparison voltage setting module is used to obtain the comparison voltage U by voltage division. f ; The fault diagnosis and indication module is used to determine the fault based on the output voltage U. t℃ And compare voltage U fTo determine whether the temperature sensor is online.

[0007] Preferably, the temperature detection module includes a configuration resistor Rs and a resistor Rt; one end of the configuration resistor Rs is connected to the positive terminal of the power supply, and the other end is electrically connected to the resistor Rt and the fault identification indicator module respectively; the other end of the resistor Rt is connected to the negative terminal of the power supply and ground; the voltage applied by the power supply is U.

[0008] Preferably, the comparison voltage setting module includes a potentiometer Rp; the input terminal of the potentiometer Rp is connected to the positive terminal of the power supply; the output terminal of the potentiometer Rp is connected to the negative terminal of the power supply and ground; the adjustable terminal of the potentiometer Rp is electrically connected to the fault diagnosis indication module; and the voltage applied by the power supply is U.

[0009] Preferably, the fault diagnosis and indication module includes a comparator, a pull-up resistor R, a DIP switch K, an AND gate, a light-emitting diode LED1, and a current-limiting resistor R1. The non-inverting input of the comparator is electrically connected to the configuration resistor Rs and the resistor Rt, respectively. The inverting input of the comparator is electrically connected to the adjustable terminal of the potentiometer Rp. The output of the comparator is electrically connected to input 1 of the AND gate. Input 2 of the AND gate is electrically connected to one end of the pull-up resistor R and one end of the DIP switch K, respectively. The other end of the pull-up resistor R is electrically connected to the positive terminal of the power supply. The other end of the DIP switch K is grounded. The output of the AND gate is electrically connected to the positive terminal of the light-emitting diode LED1. The negative terminal of the light-emitting diode LED1 is electrically connected to one end of the current-limiting resistor R1. The other end of the current-limiting resistor R1 is grounded.

[0010] Preferably, the non-inverting input terminal of the comparator inputs and outputs voltage U. t℃ The inverting input of the comparator receives the comparison voltage U. f .

[0011] Preferably, the system also includes a comprehensive discrimination indicator module; the comprehensive discrimination indicator module is electrically connected to the fault discrimination indicator module.

[0012] Preferably, the fault diagnosis indication module includes an OR gate, a light-emitting diode (LED0), and a current-limiting resistor R0; the OR gate includes n input terminals; the output terminal of the AND gate in the fault diagnosis indication module is electrically connected to one input terminal of the OR gate; the output terminal of the OR gate is electrically connected to the positive terminal of the LED0; the negative terminal of the LED0 is electrically connected to one end of the current-limiting resistor R0; and the other end of the current-limiting resistor R0 is grounded.

[0013] Compared with the prior art, the advantages of this utility model are: (1) The circuit structure of this utility model is simple and the cost is low. It can intuitively indicate whether the temperature sensor is online and can distinguish between sensor disconnection and sensor wire breakage. Attached Figure Description

[0014] Figure 1This is a schematic block diagram of an online temperature sensor indicating circuit according to the present invention. Figure 2 This is a circuit diagram of the temperature detection module in this utility model; Figure 3 This is a circuit diagram of the voltage comparison setting module in this utility model; Figure 4 This is a circuit diagram of a fault diagnosis and indication module in this utility model; Figure 5 This is a circuit diagram of the integrated discrimination indication module in this utility model. Detailed Implementation

[0015] To more clearly illustrate the embodiments of this utility model, the specific implementation methods of this utility model will be described below with reference to the accompanying drawings. Obviously, the drawings described below are merely some embodiments of this utility model. For those skilled in the art, other drawings and other implementation methods can be obtained based on these drawings without any creative effort.

[0016] Example: like Figure 1 As shown, this utility model provides an online temperature sensor indication circuit, including a temperature detection module, a comparison voltage setting module, and a fault diagnosis indication module; the temperature detection module and the comparison voltage setting module are both electrically connected to the fault diagnosis indication module. The temperature detection module is used to detect and obtain the output voltage U. t℃ ; The comparison voltage setting module is used to obtain the comparison voltage U by voltage division. f ; The fault diagnosis and indication module is used to determine the fault based on the output voltage U. t℃ And compare voltage U f To determine whether the temperature sensor is online.

[0017] Furthermore, such as Figure 2 As shown, the temperature detection module includes a configuration resistor Rs and a resistor Rt; one end of the configuration resistor Rs is connected to the positive terminal of the power supply, and the other end is electrically connected to the resistor Rt and the fault judgment indicator module respectively; the other end of the resistor Rt is connected to the negative terminal of the power supply and ground; the voltage applied by the power supply is U.

[0018] Furthermore, such as Figure 3 As shown, the comparison voltage setting module includes a potentiometer Rp; the input terminal of the potentiometer Rp is connected to the positive terminal of the power supply; the output terminal of the potentiometer Rp is connected to the negative terminal of the power supply and ground; the adjustable terminal of the potentiometer Rp is electrically connected to the fault diagnosis indication module; the voltage applied by the power supply is U.

[0019] Furthermore, such as Figure 4 As shown, the fault diagnosis and indication module includes a comparator, a pull-up resistor R, a DIP switch K, an AND gate, an LED1, and a current-limiting resistor R1. The non-inverting input of the comparator is electrically connected to the configuration resistor Rs and the resistor Rt, respectively. The inverting input of the comparator is electrically connected to the adjustable terminal of the potentiometer Rp. The output of the comparator is electrically connected to input 1 of the AND gate. Input 2 of the AND gate is electrically connected to one end of the pull-up resistor R and one end of the DIP switch K, respectively. The other end of the pull-up resistor R is electrically connected to the positive terminal of the power supply. The other end of the DIP switch K is grounded. The output of the AND gate is electrically connected to the positive terminal of the LED1. The negative terminal of the LED1 is electrically connected to one end of the current-limiting resistor R1. The other end of the current-limiting resistor R1 is grounded.

[0020] Furthermore, the non-inverting input terminal of the comparator receives the output voltage U. t℃ The inverting input of the comparator receives the comparison voltage U. f .

[0021] Furthermore, it also includes a comprehensive discrimination indication module; the comprehensive discrimination indication module is electrically connected to the fault discrimination indication module.

[0022] Furthermore, such as Figure 5 As shown, the fault diagnosis indication module includes an OR gate, a light-emitting diode (LED0), and a current-limiting resistor (R0); the OR gate includes n input terminals; the output terminal of the AND gate in the fault diagnosis indication module is electrically connected to one input terminal of the OR gate; the output terminal of the OR gate is electrically connected to the positive terminal of the LED0; the negative terminal of the LED0 is electrically connected to one end of the current-limiting resistor (R0); the other end of the current-limiting resistor (R0) is grounded.

[0023] The working principle of this utility model is as follows: The system includes a temperature detection module, a comparison voltage setting module, a fault diagnosis indicator module, and a comprehensive diagnosis indicator module to indicate that the temperature sensor is offline (disconnected) during a fault.

[0024] Typically, the detection circuit (temperature detection module) of an NTC sensor is based on... Figure 2 Wiring, output voltage U t℃ =U*Rt / (Rs+Rt). The requirement is that at the lowest detection temperature (e.g., -20℃), U... t℃ = (0.9-0.95)U, where Rs is the resistance value.

[0025] The operating voltage U is divided by potentiometer Rp to obtain the comparison voltage U. f U f Adjustable within the range of (0.9-1)U, and within the temperature testing range, U f Greater than U t℃ .

[0026] U f and U t℃ The positive and negative inputs of the comparator are connected to the positive and negative inputs respectively, and the output of the comparator is connected to input 1 of the AND gate.

[0027] The input terminal 2 of the AND gate is connected to a pull-up resistor R and a DIP switch K; one end of the pull-up resistor R is connected to the positive terminal of the working voltage, and one end of the DIP switch K is connected to the working ground terminal; when the temperature sensor is not connected, the DIP switch K is set to the closed position.

[0028] The output of the AND gate is connected to LED1, and LED1 is connected to the current-limiting resistor R1.

[0029] When the temperature sensor is correctly connected and working properly, U f >U t℃ When the comparator outputs a low level, AND gate input 1 is low, AND gate input 2 is high, and AND gate output is low, the LED does not light up.

[0030] When the temperature sensor is poorly connected, open-circuited, or disconnected, U f <U t℃ When the comparator outputs a high level, AND gate input 1 is high, AND gate input 2 is high, and AND gate output is high, the LED lights up.

[0031] When the temperature sensor is not connected, closing the DIP switch K will lower the input level of the AND gate and keep the output level low, so the LED1 will not light up.

[0032] For multi-channel temperature detection, each channel is structured as described above, corresponding to an LED for indication. Simultaneously, the outputs of each AND gate are connected to the inputs of a multi-input OR gate, and the output of the OR gate is connected to LED0, with LED0 connected in series with a current-limiting resistor R0. When one sensor is disconnected, a high level is detected at one of the OR gate inputs, causing the OR gate to output a high level, LED0 to illuminate, indicating a sensor disconnection. LED0 serves as a general fault indicator.

[0033] This utility model has a simple circuit structure and low cost. It can intuitively indicate whether the temperature sensor is online and can distinguish between sensor not connected and sensor disconnection fault.

[0034] The above description is only a detailed explanation of the preferred embodiments and principles of this utility model. For those skilled in the art, there may be changes in the specific implementation methods based on the ideas provided by this utility model, and these changes should also be considered within the protection scope of this utility model.

Claims

1. An online temperature sensor indication circuit, characterized in that, It includes a temperature detection module, a comparison voltage setting module, and a fault diagnosis indication module; the temperature detection module and the comparison voltage setting module are both electrically connected to the fault diagnosis indication module; The temperature detection module is used to detect and obtain the output voltage U. t℃ ; The comparison voltage setting module is used to obtain the comparison voltage U by voltage division. f ; The fault diagnosis and indication module is used to determine the fault based on the output voltage U. t℃ And compare voltage U f To determine whether the temperature sensor is online.

2. The online temperature sensor indicating circuit according to claim 1, characterized in that, The temperature detection module includes a configuration resistor Rs and a resistor Rt; one end of the configuration resistor Rs is connected to the positive terminal of the power supply, and the other end is electrically connected to the resistor Rt and the fault identification indicator module respectively; the other end of the resistor Rt is connected to the negative terminal of the power supply and ground; the voltage applied by the power supply is U.

3. The online temperature sensor indicating circuit according to claim 2, characterized in that, The comparison voltage setting module includes a potentiometer Rp; the input terminal of the potentiometer Rp is connected to the positive terminal of the power supply; the output terminal of the potentiometer Rp is connected to the negative terminal of the power supply and ground; the adjustable terminal of the potentiometer Rp is electrically connected to the fault diagnosis indication module; the voltage applied by the power supply is U.

4. The online temperature sensor indicating circuit according to claim 3, characterized in that, The fault diagnosis and indication module includes a comparator, a pull-up resistor R, a DIP switch K, an AND gate, an LED1, and a current-limiting resistor R1. The non-inverting input of the comparator is electrically connected to the configuration resistor Rs and the resistor Rt, respectively. The inverting input of the comparator is electrically connected to the adjustable terminal of the potentiometer Rp. The output of the comparator is electrically connected to input 1 of the AND gate. Input 2 of the AND gate is electrically connected to one end of the pull-up resistor R and one end of the DIP switch K, respectively. The other end of the pull-up resistor R is electrically connected to the positive terminal of the power supply. The other end of the DIP switch K is grounded. The output of the AND gate is electrically connected to the positive terminal of the LED1. The negative terminal of the LED1 is electrically connected to one end of the current-limiting resistor R1. The other end of the current-limiting resistor R1 is grounded.

5. The online temperature sensor indicating circuit according to claim 4, characterized in that, The non-inverting input terminal of the comparator receives and outputs voltage U. t℃ The inverting input of the comparator receives the comparison voltage U. f .

6. The online temperature sensor indicating circuit according to claim 4, characterized in that, It also includes a comprehensive discrimination indicator module; the comprehensive discrimination indicator module is electrically connected to the fault discrimination indicator module.

7. The online temperature sensor indicating circuit according to claim 6, characterized in that, The fault diagnosis and indication module includes an OR gate, a light-emitting diode (LED0), and a current-limiting resistor (R0); the OR gate includes n input terminals; the output terminal of the AND gate in the fault diagnosis and indication module is electrically connected to one input terminal of the OR gate; the output terminal of the OR gate is electrically connected to the positive terminal of the LED0; the negative terminal of the LED0 is electrically connected to one end of the current-limiting resistor (R0); the other end of the current-limiting resistor (R0) is grounded.

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