CN213067984U - Constant current circuit for temperature measurement and circuit breaker mechanical characteristic monitoring device - Google Patents
Constant current circuit for temperature measurement and circuit breaker mechanical characteristic monitoring device Download PDFInfo
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- CN213067984U CN213067984U CN202020550192.4U CN202020550192U CN213067984U CN 213067984 U CN213067984 U CN 213067984U CN 202020550192 U CN202020550192 U CN 202020550192U CN 213067984 U CN213067984 U CN 213067984U
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Abstract
The utility model provides a constant current circuit for temperature measurement, circuit breaker mechanical characteristic monitoring devices, the output of the first amplifying circuit of the constant current circuit for temperature measurement is connected with the input of the second amplifying circuit through the second resistor, the two ends of the first resistor are respectively connected with the reference voltage end and the input of the second amplifying circuit; the output end of the second amplifying circuit is connected with the input end of the first amplifying circuit through a third resistor, one end of the thermocouple is grounded, and the other end of the thermocouple is connected with the input end of the first amplifying circuit. The utility model discloses a cooperation of first amplifier circuit and second amplifier circuit produces a invariable pressure differential irrelevant with voltage ripple, thermocouple resistance between output and the input of first amplifier circuit of second amplifier circuit to utilize this pressure differential to produce a invariable electric current, calculate the resistance of thermocouple through the voltage that this electric current produced on the thermocouple, and then calculate the current temperature, avoided the undulant influence of external voltage, improved temperature measurement's accuracy.
Description
Technical Field
The utility model relates to a circuit breaker mechanical characteristics monitoring field especially relates to a constant current circuit, circuit breaker mechanical characteristics monitoring devices for temperature measurement.
Background
With the rapid development of electric power industry and the rapid advance of electric power automation systems in China, the regular maintenance work of power supply equipment of the electric power system is not more and more suitable for the actual needs of electric power production. The online monitoring of the equipment state is gradually introduced into the field of power system production research.
The breaker is an important executive component of the power system, is a large-scale power device which is only second to a generator and a transformer, completes switching operation when the breaker is normally operated, and accesses the device or a line into a power grid or quits the operation to play a role in operation control; when equipment and a line have faults, the fault line can be quickly cut off, normal operation of a fault-free part is ensured, and the operation protection effect is achieved. However, the circuit breaker is also an important power device with the most frequent failure, maintenance and parameter measurement, and has a high failure rate in the operation process, which easily causes grid accidents and causes large economic loss, so that a very high requirement is provided for the reliability of the circuit breaker.
In the prior art, the reliability of the circuit breaker is detected by using a mechanical characteristic monitoring mode of the circuit breaker, and the temperature of the circuit breaker needs to be measured during the mechanical characteristic monitoring. Thermocouples are often used to measure the temperature. However, the measurement accuracy of the thermocouple is easily affected by voltage fluctuation, while the conventional resistance voltage division method is adopted to supply power to the thermocouple, and the voltage provided by the resistance voltage division method is not only low in accuracy, but also easily affected by external voltage fluctuation, so that the temperature measurement of the thermocouple is affected, and the temperature is difficult to accurately measure.
SUMMERY OF THE UTILITY MODEL
In order to overcome prior art not enough, the utility model provides a constant current circuit is used in temperature measurement, circuit breaker mechanical characteristic monitoring devices, cooperation through first amplifier circuit and second amplifier circuit, produce one and voltage ripple between the output of second amplifier circuit and first amplifier circuit's input, the invariable pressure differential that the thermocouple resistance is irrelevant, and utilize this pressure differential to produce a invariable electric current, the resistance of thermocouple is calculated to the voltage that produces on the thermocouple through this electric current, and then calculate the current temperature, the undulant influence of external voltage has been avoided, the accuracy of temperature measurement has been improved.
In order to solve the above problem, the utility model discloses a technical scheme do: the utility model provides a constant current circuit is used in temperature measurement, constant current circuit is used in circuit breaker mechanical characteristics monitoring for the temperature measurement, constant current circuit is used in the temperature measurement includes: the thermocouple comprises a first amplifying circuit, a second amplifying circuit, a first resistor, a second resistor, a third resistor and a thermocouple, wherein the resistance values of the first resistor and the second resistor are the same, the voltage of an output end of the first amplifying circuit is equal to that of an input end, the voltage of the output end of the second amplifying circuit is twice of that of the input end, and the currents of the input ends of the first amplifying circuit and the second amplifying circuit are zero; the output end of the first amplifying circuit is connected with the input end of the second amplifying circuit through a second resistor, and two ends of the first resistor are respectively connected with the reference voltage end and the input end of the second amplifying circuit; the output end of the second amplifying circuit is connected with the input end of the first amplifying circuit through the third resistor, one end of the thermocouple is grounded, and the other end of the thermocouple is connected with the input end of the first amplifying circuit.
Furthermore, the first amplifying circuit comprises a first operational amplifier, wherein the homodromous input end of the first operational amplifier is connected with the thermocouple, and the inverting input end and the output end of the first operational amplifier are connected with the second resistor.
Furthermore, the second amplifying circuit comprises a second operational amplifier, a fourth resistor and a fifth resistor, wherein the homodromous input end of the second operational amplifier is connected with the output end of the first amplifying resistor through the second resistor, the inverting input end of the second operational amplifier is grounded through the fourth resistor, and two ends of the fifth resistor are respectively connected with the inverting input end and the output end of the second operational amplifier.
Further, the resistance value of the fourth resistor is equal to the resistance value of the fifth resistor.
Further, the voltage of the reference voltage terminal is 2.5V.
Based on the same inventive concept, the utility model also provides a circuit breaker mechanical characteristics monitoring devices, circuit breaker mechanical characteristics monitoring devices includes: the device comprises a reference voltage generating chip, a constant current circuit for temperature measurement and an analog-to-digital converter; the reference voltage end of the reference voltage generating chip is connected with the constant current circuit for temperature measurement, and the reference voltage is input to the constant current circuit for temperature measurement through the reference voltage generating chip; the analog-to-digital converter is connected with a thermocouple in the constant current circuit for temperature measurement, and the voltage value of the thermocouple is obtained through the analog-to-digital converter; the constant current circuit for temperature measurement includes: the thermocouple comprises a first amplifying circuit, a second amplifying circuit, a first resistor, a second resistor, a third resistor and a thermocouple, wherein the resistance values of the first resistor and the second resistor are the same, the voltage of an output end of the first amplifying circuit is equal to that of an input end, the voltage of the output end of the second amplifying circuit is twice of that of the input end, and the currents of the input ends of the first amplifying circuit and the second amplifying circuit are zero; the output end of the first amplifying circuit is connected with the input end of the second amplifying circuit through a second resistor, and two ends of the first resistor are respectively connected with the reference voltage end and the input end of the second amplifying circuit; the output end of the second amplifying circuit is connected with the input end of the first amplifying circuit through the third resistor, one end of the thermocouple is grounded, and the other end of the thermocouple is connected with the input end of the first amplifying circuit.
Furthermore, the first amplifying circuit comprises a first operational amplifier, wherein the homodromous input end of the first operational amplifier is connected with the thermocouple, and the inverting input end and the output end of the first operational amplifier are connected with the second resistor.
Furthermore, the second amplifying circuit comprises a second operational amplifier, a fourth resistor and a fifth resistor, wherein the homodromous input end of the second operational amplifier is connected with the output end of the first amplifying resistor through the second resistor, the inverting input end of the second operational amplifier is grounded through the fourth resistor, and two ends of the fifth resistor are respectively connected with the inverting input end and the output end of the second operational amplifier.
Further, the resistance value of the fourth resistor is equal to the resistance value of the fifth resistor.
Further, the voltage of the reference voltage terminal is 2.5V.
Compared with the prior art, the beneficial effects of the utility model reside in that: through the cooperation of the first amplifying circuit and the second amplifying circuit, a constant differential pressure irrelevant to voltage ripples and thermocouple resistance is generated between the output of the second amplifying circuit and the input of the first amplifying circuit, a constant current is generated by utilizing the differential pressure, the resistance of the thermocouple is calculated through the voltage generated by the current on the thermocouple, the current temperature is calculated, the influence of external voltage fluctuation is avoided, and the accuracy of temperature measurement is improved.
Drawings
Fig. 1 is a circuit diagram of an embodiment of the constant current circuit for measuring temperature of the present invention;
FIG. 2 is a circuit diagram of another embodiment of the constant current circuit for measuring temperature of the present invention;
fig. 3 is a structural diagram of an embodiment of the device for monitoring mechanical characteristics of a circuit breaker of the present invention.
In the figure: r1: a first resistor; r2, a second resistor; r3, third resistor; r4, fourth resistor; r5, fifth resistor; r6, thermocouple; u1, a first operational amplifier; u2, a second operational amplifier.
Detailed Description
The present invention will be further described with reference to the accompanying drawings and the detailed description, and it should be noted that the embodiments or technical features described below can be arbitrarily combined to form a new embodiment without conflict.
Referring to fig. 1-2, fig. 1 is a circuit diagram of an embodiment of a constant current circuit for measuring temperature according to the present invention; fig. 2 is a circuit diagram of another embodiment of the constant current circuit for temperature measurement according to the present invention. The constant current circuit for temperature measurement of the present invention will be described in detail with reference to fig. 1-2.
In this embodiment, the constant current circuit for temperature measurement is applied to monitoring the mechanical characteristics of the circuit breaker, and includes: the constant current circuit for temperature measurement includes: the circuit comprises a first amplifying circuit, a second amplifying circuit, a first resistor R1, a second resistor R2, a third resistor R3 and a thermocouple R6, wherein the resistance values of the first resistor R1 and the second resistor R2 are the same, the voltage of an output end of the first amplifying circuit is equal to that of an input end, the voltage of the output end of the second amplifying circuit is twice of that of the input end, and the currents of the input ends of the first amplifying circuit and the second amplifying circuit are zero; the output end of the first amplifying circuit is connected with the input end of the second amplifying circuit through a second resistor R2, and two ends of a first resistor R1 are respectively connected with the reference voltage end and the input end of the second amplifying circuit; the output end of the second amplifying circuit is connected with the input end of the first amplifying circuit through a third resistor R3, one end of the thermocouple R6 is grounded, and the other end of the thermocouple R6 is connected with the input end of the first amplifying circuit.
In other embodiments, the constant current for measuring temperature may also be used for measuring water temperature, furnace temperature, and other object temperatures, which is not limited herein.
In a specific embodiment, the first resistor R1 and the second resistor R2 both have a resistance of 20K Ω, and the third resistor R3 has a resistance of 2.5K Ω. In other embodiments, the resistances of the first resistor R1, the second resistor R2, and the third resistor R3 may be other values, and only the resistances of the first resistor R1 and the second resistor R2 are equal, which is not limited herein.
In this embodiment, the first amplifying circuit includes a first operational amplifier U1, the first operational amplifier U1 has a unidirectional input connected to the thermocouple R6, and an inverted input and an output connected to the second resistor R2.
In one specific embodiment, the first operational amplifier U1 is a voltage follower having a voltage at the non-inverting input equal to the voltage at the output.
In this embodiment, the second amplifying circuit includes a second operational amplifier U2, a fourth resistor R4, and a fifth resistor R5, wherein the inverting input terminal of the second operational amplifier U2 is connected to the output terminal of the first amplifying resistor through the second resistor R2, the inverting input terminal is connected to ground through the fourth resistor R4, and two ends of the fifth resistor R5 are respectively connected to the inverting input terminal and the output terminal of the second operational amplifier U2.
In this embodiment, the second operational amplifier U2 is a same-direction scaling circuit, and the voltage of the same-direction input terminal of the same-direction scaling circuit is half of the voltage of the output terminal.
In the present embodiment, the resistance of the fourth resistor R4 is equal to the resistance of the fifth resistor R5, and both are 20K Ω.
In this embodiment, the voltage of the reference voltage terminal is 2.5V.
The utility model discloses a feedback cooperation, the differential pressure of guaranteeing on the third resistance R3 of two operational amplifier are stabilized at the fixed value, under the certain circumstances of resistance of third resistance R3, according to ampere theorem electric current I ═ voltage U resistance R, voltage U and resistance R are all fixed now, that is to say the electric current that flows on the third resistance R3 is invariable. While the current flowing through the third resistor R3 continues to flow through the thermocouple R6, the current is independent of the change in resistance of the thermocouple R6. The circuit operating condition did not change due to the change in resistance of thermocouple R6. Therefore, the voltage of the thermocouple R6 is only related to the resistance value of the thermocouple R6, and the accuracy of temperature monitoring is improved.
The working principle of the constant current circuit for temperature measurement is further explained below.
The reference voltage terminal of the reference voltage generating chip generates 2.5V, because the input impedance of the second operational amplifier U2 is very high, and is in the G ohm level, i.e. the current I5 is very small and can be regarded as 0. According to kirchhoff's current law, the sum of the currents at the Vx points in fig. 2 is 0. I.e. I1+ I2+ I5 is 0. I5 is 0, i.e. I1+ I2 is 0.
Because I1 ═ (Vo' -Vx)/R2; i2 ═ (Vref _2.5v-Vx) R1. And I1+ I2 ═ 0. It can be obtained (Vo' -Vx)/R2+ (Vref _2.5v-Vx) R1 ═ 0. Fig. 2 shows R1 ═ R2. Therefore, (Vo' -Vx) + (Vref _2.5v-Vx) ═ 0 can be obtained; the simplified value can be 2Vx-Vo ═ Vref _2.5 v.
The second operational amplifier U2 in fig. 2 is an in-phase proportional amplifier circuit, i.e., Vx' ═ (1+ R4/R3) Vx (1+20K/20K) Vx 2 Vx. The first operational amplifier U1 is a voltage follower, i.e., Vo' ═ Vo; that is, the voltage drop across resistor R5 is equal to Vx '-Vo — 2 Vx-Vo'. Further, (2 Vx-Vo')/R5 of the current in the third resistor R3 is 2.5V/2.5K is 1 mA. The input impedance of the first operational amplifier U1 is very high, and is in the G ohm level, that is, the input current I4 of the first operational amplifier U1 is very small, and can be regarded as 0 for processing.
Therefore, the current I6, I3, flowing through the thermocouple R6 is 1mA, and the current is generated by feedback cooperation of the operational amplifier U1 and U2, regardless of the resistance value of the thermocouple R6. And inputting Vo to an analog-to-digital converter connected with the constant current circuit for temperature measurement to realize analog-to-digital conversion, calculating the voltage of Uo, dividing the voltage by the current 1mA, calculating the current resistance of the thermocouple R6 in a reverse mode, and finally, reversely calculating the current temperature according to the resistance of R6.
Has the advantages that: the utility model discloses a constant current circuit for temperature measurement passes through the cooperation of first amplifier circuit and second amplifier circuit, produce a invariable pressure differential irrelevant with voltage ripple, thermocouple resistance between the output of second amplifier circuit and the input of first amplifier circuit, and utilize this pressure differential to produce a invariable electric current, the resistance of voltage calculation thermocouple through this electric current production on the thermocouple, and then calculate the current temperature, the undulant influence of external voltage has been avoided, temperature measurement's accuracy has been improved.
Based on the same inventive concept, the utility model discloses still provide a circuit breaker mechanical characteristics monitoring devices, please refer to fig. 3, fig. 3 is the utility model discloses the structure chart of circuit breaker mechanical characteristics monitoring devices embodiment, it is right to combine fig. 3 the utility model discloses a circuit breaker mechanical characteristics monitoring devices does the concrete description.
The circuit breaker mechanical characteristic monitoring device includes: the device comprises a reference voltage generating chip, a constant current circuit for temperature measurement and an analog-to-digital converter; the reference voltage end of the reference voltage generating chip is connected with the constant current circuit for temperature measurement, and the reference voltage is input into the constant current circuit for temperature measurement through the reference voltage generating chip; the analog-to-digital converter is connected with a thermocouple in the constant current circuit for temperature measurement, and the voltage value of the thermocouple is obtained through the analog-to-digital converter; the constant current circuit for temperature measurement includes: the thermocouple comprises a first amplifying circuit, a second amplifying circuit, a first resistor, a second resistor, a third resistor and a thermocouple, wherein the resistance values of the first resistor and the second resistor are the same, the voltage of an output end of the first amplifying circuit is equal to that of an input end, the voltage of an output end of the second amplifying circuit is twice of that of the input end, and the currents of the input ends of the first amplifying circuit and the second amplifying circuit are zero; the output end of the first amplifying circuit is connected with the input end of the second amplifying circuit through a second resistor, and two ends of the first resistor are respectively connected with the reference voltage end and the input end of the second amplifying circuit; the output end of the second amplifying circuit is connected with the input end of the first amplifying circuit through a third resistor, one end of the thermocouple is grounded, and the other end of the thermocouple is connected with the input end of the first amplifying circuit.
In other embodiments, the constant current for measuring temperature may also be used for measuring water temperature, furnace temperature, and other object temperatures, which is not limited herein.
In a specific embodiment, the first resistor and the second resistor have a resistance of 20K Ω, and the third resistor has a resistance of 2.5K Ω. In other embodiments, the resistances of the first resistor, the second resistor, and the third resistor may be other values, and only the resistances of the first resistor and the second resistor are equal, which is not limited herein.
In this embodiment, the first amplifying circuit includes a first operational amplifier, a same-direction input end of the first operational amplifier is connected to the thermocouple, and an opposite-direction input end and an output end of the first operational amplifier are connected to the second resistor.
In a specific embodiment, the first operational amplifier is a voltage follower, and the voltage of the same-direction input end of the voltage follower is equal to the voltage of the output end of the voltage follower.
In this embodiment, the second amplifying circuit includes a second operational amplifier, a fourth resistor, and a fifth resistor, wherein a non-inverting input terminal of the second operational amplifier is connected to an output terminal of the first amplifying resistor through the second resistor, an inverting input terminal of the second operational amplifier is grounded through the fourth resistor, and two ends of the fifth resistor are respectively connected to an inverting input terminal and an output terminal of the second operational amplifier.
In this embodiment, the second operational amplifier is a same-direction proportional amplifying circuit, and the voltage of the same-direction input end of the same-direction proportional amplifying circuit is half of the voltage of the output end.
In this embodiment, the resistance of the fourth resistor is equal to the resistance of the fifth resistor, and both are 20K Ω.
In this embodiment, the voltage of the reference voltage terminal is 2.5V.
The utility model discloses a feedback cooperation, the differential pressure of guaranteeing on the third resistance of two operational amplifier are stabilized at the fixed value, under the certain circumstances of resistance of third resistance, according to ampere theorem electric current I ═ voltage U resistance R, voltage U and resistance R are all fixed now, that is to say the electric current that flows on the third resistance is invariable. While the current flowing through the third resistor continues to flow through the thermocouple regardless of the change in the resistance of the thermocouple. The working state of the circuit is not changed due to the change of the resistance value of the thermocouple. Therefore, the voltage of the thermocouple is only related to the resistance value of the thermocouple, and the accuracy of temperature monitoring is improved.
The working principle of the constant current circuit for temperature measurement has been described in the above embodiments, and is not described herein.
Has the advantages that: the utility model discloses a circuit breaker mechanical characteristic monitoring devices is through the cooperation of first amplifier circuit and second amplifier circuit, produce a invariable pressure differential irrelevant with voltage ripple, thermocouple resistance between the output of second amplifier circuit and first amplifier circuit's input, and utilize this pressure differential to produce a invariable electric current, the resistance of thermocouple is calculated to the voltage that produces on the thermocouple through this electric current, and then calculate the current temperature, the undulant influence of external voltage has been avoided, the accuracy of temperature measurement has been improved.
The above embodiments are only preferred embodiments of the present invention, and the protection scope of the present invention cannot be limited thereby, and any insubstantial changes and substitutions made by those skilled in the art based on the present invention are all within the protection scope of the present invention.
Claims (10)
1. The constant current circuit for temperature measurement is applied to monitoring of mechanical characteristics of a circuit breaker, and comprises: the thermocouple comprises a first amplifying circuit, a second amplifying circuit, a first resistor, a second resistor, a third resistor and a thermocouple, wherein the resistance values of the first resistor and the second resistor are the same, the voltage of an output end of the first amplifying circuit is equal to that of an input end, the voltage of the output end of the second amplifying circuit is twice of that of the input end, and the currents of the input ends of the first amplifying circuit and the second amplifying circuit are zero;
the output end of the first amplifying circuit is connected with the input end of the second amplifying circuit through a second resistor, and two ends of the first resistor are respectively connected with the reference voltage end and the input end of the second amplifying circuit;
the output end of the second amplifying circuit is connected with the input end of the first amplifying circuit through the third resistor, one end of the thermocouple is grounded, and the other end of the thermocouple is connected with the input end of the first amplifying circuit.
2. The constant current circuit for temperature measurement according to claim 1, wherein the first amplifier circuit includes a first operational amplifier, a homodromous input terminal of the first operational amplifier is connected to the thermocouple, and a reverse input terminal and an output terminal thereof are connected to the second resistor.
3. The constant current circuit for temperature measurement according to claim 1, wherein the second amplification circuit includes a second operational amplifier, a fourth resistor, and a fifth resistor, a same-direction input terminal of the second operational amplifier is connected to an output terminal of the first amplification resistor through the second resistor, an inverted-phase input terminal of the second operational amplifier is grounded through the fourth resistor, and both ends of the fifth resistor are connected to an inverted-phase input terminal and an output terminal of the second operational amplifier, respectively.
4. The constant current circuit for temperature measurement according to claim 3, wherein a resistance value of the fourth resistor is equal to a resistance value of the fifth resistor.
5. The constant current circuit for temperature measurement according to claim 1, wherein a voltage of the reference voltage terminal is 2.5V.
6. A circuit breaker mechanical characteristic monitoring device, comprising: the device comprises a reference voltage generating chip, a constant current circuit for temperature measurement and an analog-to-digital converter;
the reference voltage end of the reference voltage generating chip is connected with the constant current circuit for temperature measurement, and the reference voltage is input to the constant current circuit for temperature measurement through the reference voltage generating chip;
the analog-to-digital converter is connected with a thermocouple in the constant current circuit for temperature measurement, and the voltage value of the thermocouple is obtained through the analog-to-digital converter;
the constant current circuit for temperature measurement includes: the thermocouple comprises a first amplifying circuit, a second amplifying circuit, a first resistor, a second resistor, a third resistor and a thermocouple, wherein the resistance values of the first resistor and the second resistor are the same, the voltage of an output end of the first amplifying circuit is equal to that of an input end, the voltage of the output end of the second amplifying circuit is twice of that of the input end, and the currents of the input ends of the first amplifying circuit and the second amplifying circuit are zero;
the output end of the first amplifying circuit is connected with the input end of the second amplifying circuit through a second resistor, and two ends of the first resistor are respectively connected with the reference voltage end and the input end of the second amplifying circuit;
the output end of the second amplifying circuit is connected with the input end of the first amplifying circuit through the third resistor, one end of the thermocouple is grounded, and the other end of the thermocouple is connected with the input end of the first amplifying circuit.
7. The circuit breaker mechanical characteristic monitoring device of claim 6, wherein the first amplifying circuit comprises a first operational amplifier, a same-direction input end of the first operational amplifier is connected with the thermocouple, and an opposite-direction input end and an output end of the first operational amplifier are connected with the second resistor.
8. The apparatus for monitoring mechanical characteristics of circuit breaker according to claim 6, wherein said second amplifying circuit comprises a second operational amplifier, a fourth resistor and a fifth resistor, wherein a same-direction input terminal of said second operational amplifier is connected to an output terminal of said first amplifying resistor through said second resistor, an inverted-direction input terminal of said second operational amplifier is connected to ground through said fourth resistor, and two terminals of said fifth resistor are connected to an inverted-direction input terminal and an output terminal of said second operational amplifier, respectively.
9. The circuit breaker mechanical characteristic monitoring device of claim 8, wherein the fourth resistor has a resistance equal to the fifth resistor.
10. The apparatus for monitoring the mechanical characteristics of a circuit breaker according to claim 6, wherein the voltage of said reference voltage terminal is 2.5V.
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| CN202020550192.4U CN213067984U (en) | 2020-04-14 | 2020-04-14 | Constant current circuit for temperature measurement and circuit breaker mechanical characteristic monitoring device |
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| CN202020550192.4U CN213067984U (en) | 2020-04-14 | 2020-04-14 | Constant current circuit for temperature measurement and circuit breaker mechanical characteristic monitoring device |
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