阅读说明：本技术 一种变压器绕组温度的检测电路 (Detection circuit for temperature of transformer winding ) 是由 祝祥林 于 2020-12-30 设计创作，主要内容包括：本申请实施例提供了一种变压器绕组温度的检测电路,本电路包括第一信号转换电路和第二信号转换电路,第一信号转换电路包括串联的第一温度继电器和导线,第一温度继电器的动作温度为预设的第一温度,第一温度继电器放置于预设的被测热点处,第一信号转换电路环绕变压器绕组的铁芯放置。第二信号转换电路包括第一发光二极管。第一温度继电器响应于被测热点的温度达到第一温度动作,第一温度继电器两端电压发生变化,第一发光二极管在不同的电压下的状态不同。本电路利用铁芯的磁通变化取电,将温度信号转换为电压信号,避免外部供电设备和被测热点的绕组电压压差过大导致电气元件损坏甚至电击事故,提高安全性,特别是在高压应用场合。(The embodiment of the application provides a detection circuitry of transformer winding temperature, this circuit includes first signal conversion circuit and second signal conversion circuit, and first signal conversion circuit is including the first temperature relay and the wire of series connection, and first temperature relay's action temperature is predetermined first temperature, and first temperature relay places in predetermined surveyed hot spot department, and first signal conversion circuit places around transformer winding's iron core. The second signal conversion circuit includes a first light emitting diode. The first temperature relay responds to the fact that the temperature of the hot spot to be measured reaches a first temperature action, the voltage at two ends of the first temperature relay changes, and the states of the first light emitting diode under different voltages are different. The circuit utilizes the magnetic flux change of the iron core to obtain electricity, converts a temperature signal into a voltage signal, avoids electric element damage and even electric shock accidents caused by overlarge voltage difference of windings of external power supply equipment and a measured hot spot, improves safety, and is particularly suitable for high-voltage application occasions.)

1. A circuit for detecting a temperature of a winding of a transformer, comprising:

a first signal conversion circuit and a second signal conversion circuit;

the first signal conversion circuit comprises a first temperature relay and a lead which are connected in series, the action temperature of the first temperature relay is a preset first temperature, and the first temperature relay is placed at a preset detected hot point on a transformer winding; the first signal conversion circuit is arranged around the iron core of the transformer winding;

the second signal conversion circuit comprises an electric signal conversion device, the electric signal conversion device comprises a first light emitting diode, the first end of the first light emitting diode is connected with the first end of the first signal conversion circuit, and the second end of the first light emitting diode is connected with the second end of the first signal conversion circuit.

2. The circuit of claim 1, wherein the first signal conversion circuit further comprises a second temperature relay in series with the first temperature relay, and a first diode in parallel with the first temperature relay;

the action temperature of the second temperature relay is a preset second temperature, and the first temperature is not equal to the second temperature;

the first end of the first temperature relay is connected with the second end of the first diode, the second end of the first temperature relay is connected with the first end of the first diode, and the first end of the second temperature relay is connected with the second end of the first temperature relay.

3. The circuit of claim 2, further comprising an equipotential circuit;

the equipotential circuit comprises a preset conductor, the potential difference value between the potential of the preset conductor and the measured hot spot is smaller than a preset value, and the preset conductor is connected to any point in the first conversion circuit or any point in the second conversion circuit through a lead.

4. The circuit of claim 2 or 3, wherein a first terminal of the first light emitting diode is connected to a first terminal of the first temperature relay and a second terminal of the first light emitting diode is connected to a second terminal of the second temperature relay.

5. The circuit of claim 2 or 3, further comprising a rectifying circuit comprising a second diode, a third diode, a fourth diode, and a fifth diode; the first end of the second diode is connected with the second end of the second temperature relay, the second end of the second diode is connected with the second end of the third diode, the first end of the third diode is connected with the first end of the first temperature relay, the second end of the fourth diode is connected with the second end of the second temperature relay, the first end of the fourth diode is connected with the first end of the fifth diode, and the second end of the fifth diode is connected with the first end of the first temperature relay.

6. The circuit of claim 5, further comprising: a jamming circuit, the jamming circuit comprising: a first anti-jamming circuit and/or a second anti-jamming circuit;

the first anti-jamming circuit comprises a first resistor, the first end of the first resistor is connected with the first end of the first temperature relay, and the second end of the first resistor is connected with the second end of the second temperature relay;

the second anti-interference circuit comprises a first capacitor, wherein the first end of the first capacitor is connected with the second end of the third diode, and the second end of the first capacitor is connected with the first end of the fifth diode.

7. The circuit of claim 5 or 6, wherein a first terminal of the first light emitting diode is connected to a second terminal of the third diode, and a second terminal of the first light emitting diode is connected to a first terminal of the fifth diode.

8. The circuit of claim 5 or 6, further comprising: a current limiting circuit comprising a second resistor;

and the first end of the second resistor is connected with the second end of the third diode, and the second end of the second resistor is connected with the first end of the first light-emitting diode.

9. The circuit of claim 8, further comprising: a constant current circuit;

the constant current circuit includes: the third resistor, the fourth resistor, the voltage stabilizing diode and the triode;

the first end of the third resistor is connected with the second end of the second resistor, the second end of the third resistor is connected with the second end of the zener diode, the first end of the zener diode is connected with the first end of the fourth resistor, the second end of the fourth resistor is connected with the second end of the triode, and the first end of the triode is connected with the second end of the zener diode;

the third end of the triode is connected with the second end of the first light-emitting diode, and the first end of the voltage stabilizing diode is connected with the first end of the fifth diode;

the first end of the triode is a base electrode, the second end of the triode is an emitting electrode, and the third end of the triode is a collector electrode.

10. The circuit of claim 2 or 3, further comprising: a first current limiting resistor and a rectifier diode;

the first end of the first current-limiting resistor is connected with the second end of the second temperature relay, the second end of the first current-limiting resistor is connected with the first end of the rectifier diode, and the second end of the rectifier diode is connected with the first end of the first temperature relay;

the first end of the first light emitting diode is connected with the second end of the rectifier diode, and the second end of the first light emitting diode is connected with the first end of the rectifier diode.

11. The circuit according to claim 2 or 3, wherein the electric signal conversion device further comprises: a second current limiting resistor and a second light emitting diode;

the first end of the second current-limiting resistor is connected with the second end of the second temperature relay; the first end of the first light emitting diode and the first end of the second light emitting diode have the same polarity;

the first end of the first light-emitting diode is connected with the first end of the first temperature relay, and the second end of the first light-emitting diode is connected with the second end of the second current-limiting resistor;

and the second end of the second light-emitting diode is connected with the first end of the first temperature relay, and the first end of the second light-emitting diode is connected with the second end of the second current-limiting resistor.

Technical Field

The application relates to the technical field of automatic detection, in particular to a detection circuit for the temperature of a transformer winding.

Background

At present, the medium-high voltage frequency converter is commonly used in industrial and mining enterprises, the phase-shifting transformer can be used in the medium-high voltage frequency converter, particularly in a cascade frequency converter, in the prior art, the high-temperature phenomenon of the phase-shifting transformer is timely found through overheat detection of the phase-shifting transformer, and the damage and even the burning of the transformer induced by high temperature are avoided.

In the traditional overheat detection circuit, a temperature relay or a sensor is placed in an air passage of a high-voltage winding or a low-voltage winding, one end of a probe is close to a heating coil by wrapping a high-voltage resistant insulating tube, and the other end of the probe is connected to a PLC (or other temperature control devices). Due to the fact that an insulating tube with high thermal resistance is used, and the probe is arranged in the air channel, the detection circuit is difficult to accurately measure the temperature of the transformer winding. Meanwhile, once the quality problem occurs to the insulating tube, the high voltage of the transformer can be connected in series to the PLC (or other temperature control devices) through the temperature probe and even to a power supply network for supplying power to the PLC. Serious threats to the security of the measuring equipment and other equipment and personnel using the power supply network.

Disclosure of Invention

The invention provides a detection circuit for the temperature of a transformer winding, which aims to improve the precision and the safety of the detection of the temperature of a transformer, and comprises the following steps:

a circuit for detecting the temperature of a transformer winding, comprising:

a first signal conversion circuit and a second signal conversion circuit;

the first signal conversion circuit comprises a first temperature relay and a lead which are connected in series, the action temperature of the first temperature relay is a preset first temperature, and the first temperature relay is placed at a preset detected hot point on a transformer winding; the first signal conversion circuit is arranged around the iron core of the transformer winding;

the second signal conversion circuit comprises an electric signal conversion device, the electric signal conversion device comprises a first light emitting diode, the first end of the first light emitting diode is connected with the first end of the first signal conversion circuit, and the second end of the first light emitting diode is connected with the second end of the first signal conversion circuit.

Optionally, the first signal conversion circuit further comprises a second temperature relay connected in series with the first temperature relay, and a first diode connected in parallel with the first temperature relay;

the action temperature of the second temperature relay is a preset second temperature, and the first temperature is not equal to the second temperature;

the first end of the first temperature relay is connected with the second end of the first diode, the second end of the first temperature relay is connected with the first end of the first diode, and the first end of the second temperature relay is connected with the second end of the first temperature relay.

Optionally, an equipotential circuit is further included;

the equipotential circuit comprises a preset conductor, the potential difference value between the potential of the preset conductor and the measured hot spot is smaller than a preset value, and the preset conductor is connected to any point in the first conversion circuit or any point in the second conversion circuit through a lead.

Optionally, a first end of the first light emitting diode is connected to a first end of the first temperature relay, and a second end of the first light emitting diode is connected to a second end of the second temperature relay.

Optionally, the power supply further comprises a rectifying circuit, wherein the rectifying circuit comprises a second diode, a third diode, a fourth diode and a fifth diode; the first end of the second diode is connected with the second end of the second temperature relay, the second end of the second diode is connected with the second end of the third diode, the first end of the third diode is connected with the first end of the first temperature relay, the second end of the fourth diode is connected with the second end of the second temperature relay, the first end of the fourth diode is connected with the first end of the fifth diode, and the second end of the fifth diode is connected with the first end of the first temperature relay.

Optionally, the method further comprises: a jamming circuit, the jamming circuit comprising: a first anti-jamming circuit and/or a second anti-jamming circuit;

the first anti-jamming circuit comprises a first resistor, the first end of the first resistor is connected with the first end of the first temperature relay, and the second end of the first resistor is connected with the second end of the second temperature relay;

the second anti-interference circuit comprises a first capacitor, wherein the first end of the first capacitor is connected with the second end of the third diode, and the second end of the first capacitor is connected with the first end of the fifth diode.

Optionally, a first end of the first light emitting diode is connected to a second end of the third diode, and a second end of the first light emitting diode is connected to a first end of the fifth diode.

Optionally, the method further comprises: a current limiting circuit comprising a second resistor;

and the first end of the second resistor is connected with the second end of the third diode, and the second end of the second resistor is connected with the first end of the first light-emitting diode.

Optionally, the method further comprises: a constant current circuit;

the constant current circuit includes: the circuit comprises a third resistor, a fourth resistor, a voltage stabilizing diode and a triode.

The first end of the third resistor is connected with the second end of the second resistor, the second end of the third resistor is connected with the second end of the zener diode, the first end of the zener diode is connected with the first end of the fourth resistor, the second end of the fourth resistor is connected with the second end of the triode, and the first end of the triode is connected with the second end of the zener diode;

the third end of the triode is connected with the second end of the first light-emitting diode, and the first end of the voltage stabilizing diode is connected with the first end of the fifth diode;

the first end of the triode is a base electrode, the second end of the triode is an emitting electrode, and the third end of the triode is a collector electrode.

Optionally, the method further comprises: a first current limiting resistor and a rectifier diode;

the first end of the first current-limiting resistor is connected with the second end of the second temperature relay, the second end of the first current-limiting resistor is connected with the first end of the rectifier diode, and the second end of the rectifier diode is connected with the first end of the first temperature relay;

the first end of the first light emitting diode is connected with the second end of the rectifier diode, and the second end of the first light emitting diode is connected with the first end of the rectifier diode.

Optionally, the electrical signal conversion device further comprises: a second current limiting resistor and a second light emitting diode;

the first end of the second current-limiting resistor is connected with the second end of the second temperature relay; the first end of the first light emitting diode and the first end of the second light emitting diode have the same polarity;

the first end of the first light-emitting diode is connected with the first end of the first temperature relay, and the second end of the first light-emitting diode is connected with the second end of the second current-limiting resistor;

and the second end of the second light-emitting diode is connected with the first end of the first temperature relay, and the first end of the second light-emitting diode is connected with the second end of the second current-limiting resistor.

It can be seen from the above technical solutions that the circuit for detecting the temperature of the transformer winding provided in the embodiments of the present application includes a first signal conversion circuit and a second signal conversion circuit, where the first signal conversion circuit includes a first temperature relay and a wire connected in series, and the first signal conversion circuit is disposed around an iron core of the transformer winding, so when the transformer is powered on and operated, magnetic flux generated by the iron core generates an electromagnetic effect, so that an alternating voltage is generated at two ends of the first signal conversion circuit when the first temperature relay is closed, and no voltage is generated at two ends of the first signal conversion circuit when the first temperature relay is opened, because the operating temperature of the first temperature relay is a preset first temperature and the first temperature relay is disposed at a preset detected hot spot on the transformer winding, the first temperature relay operates in response to the temperature of the detected hot spot, the voltage at two ends of the first temperature relay is changed, and therefore the temperature signal is converted into the voltage signal. And because the second signal conversion circuit comprises the electrical signal conversion device which comprises the first light emitting diode, it can be understood that the states of the first light emitting diode under different voltages are different, thereby realizing the conversion of the voltage signal into the optical signal, therefore, the circuit realizes the self-power supply of the first signal conversion circuit, converts the temperature signal into the voltage signal and further converts the voltage signal into the optical signal.

Drawings

In order to more clearly illustrate the embodiments of the present application or the technical solutions in the prior art, the drawings used in the description of the embodiments or the prior art will be briefly described below, it is obvious that the drawings in the following description are only some embodiments of the present application, and for those skilled in the art, other drawings can be obtained according to the drawings without creative efforts.

Fig. 1 is a schematic structural diagram of a detection circuit for detecting a temperature of a transformer winding according to an embodiment of the present disclosure;

FIG. 2a is a schematic voltage waveform provided by an embodiment of the present application;

FIG. 2b is a schematic diagram of another voltage waveform provided by an embodiment of the present application;

FIG. 2c is a schematic diagram of another voltage waveform provided by an embodiment of the present application;

fig. 3 is a schematic structural diagram of a detection circuit for detecting a temperature of a winding of a transformer according to an embodiment of the present disclosure;

fig. 4a is a schematic structural diagram of a first signal conversion circuit according to an embodiment of the present disclosure;

fig. 4b is a schematic structural diagram of another first signal conversion circuit according to an embodiment of the present disclosure;

fig. 5a is a schematic structural diagram of a signal transmission conversion circuit according to an embodiment of the present disclosure;

fig. 5b is a schematic structural diagram of another signal transmission conversion circuit according to an embodiment of the present disclosure;

fig. 6 is a schematic structural diagram of a detection circuit for detecting a temperature of a winding of a transformer according to an embodiment of the present disclosure;

fig. 7 is a schematic structural diagram of a circuit for detecting a temperature of a transformer winding according to an embodiment of the present application.

Detailed Description

The technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the drawings in the embodiments of the present application, and it is obvious that the described embodiments are only a part of the embodiments of the present application, and not all of the embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present application.

The detection circuit of transformer winding temperature that this application embodiment provided belongs to well high-voltage inverter safety design, temperature detection and protection field, is applied to but not limited to and carries out overheat detection to the winding (high-voltage winding or low-voltage winding) of phase-shifting transformer. Fig. 1 is a schematic structural diagram of a circuit for detecting a transformer winding temperature according to an embodiment of the present disclosure, and as shown in fig. 1, the circuit for detecting a transformer winding temperature includes a first signal conversion circuit, a signal transmission circuit, and a second signal conversion circuit. The specific structure and the working principle of each component circuit of the detection circuit for the temperature of the transformer winding are shown in the following 1-3.

1. The structure and the working principle of the first signal conversion circuit are as follows:

the first signal conversion circuit includes: a first temperature relay SW1, a second temperature relay SW2, and a first diode D1.

Wherein SW1 is connected in parallel with D1, SW1 is connected in series with SW2, specifically, the first terminal of SW1 is connected to the second terminal (cathode) of D1, the second terminal of SW1 is connected to the first terminal (anode) of D1, and the second terminal of SW1 is connected to the first terminal of SW 2.

In this embodiment, the first terminal of the SW1 is referred to as the a terminal, the second terminal of the SW2 is referred to as the B terminal, and the voltage difference between the a terminal and the B terminal is referred to as the output voltage of the first signal conversion circuit.

It is understood that the diode is characterized by unidirectional conduction, in this embodiment, the anode of any diode is referred to as the first terminal, and the cathode of the diode is referred to as the second terminal, that is, current can only flow from the first terminal to the second terminal of the diode.

In this embodiment, the first signal conversion circuit is disposed around the iron core of the transformer winding, and the number of turns of the wire around the iron core of the transformer is any preset value.

In this embodiment, SW1 is a normally open temperature relay, SW1 is a first temperature, SW2 is a normally closed temperature relay, and SW2 is a second temperature, where the first temperature and the second temperature are preset values according to actual requirements, and in this embodiment, the first temperature is less than the second temperature. In practical applications, the specific models of SW1 and SW2 may be configured according to the first temperature and the second temperature.

In this embodiment, SW1 is placed at a first detected hot spot preset on the transformer winding, and SW2 is placed at a second detected hot spot preset on the transformer winding, it can be understood that SW1 is used for detecting the temperature of the first detected hot spot, and SW2 is used for detecting the temperature of the second detected hot spot. It should be noted that, the first measured hot spot and the second measured hot spot may be, but are not limited to, located at the same position or at adjacent positions, and since the first measured hot spot and the second measured hot spot are both located at hotter positions of the high voltage winding or the low voltage winding of the transformer, the temperature of the first measured hot spot is generally similar to that of the second measured hot spot, and both are referred to as the temperature of the measured hot spot.

When the transformer is powered on, the iron core generates magnetic flux (namely main magnetic flux of the transformer), the A end and the B end generate voltage difference, and if the SW2 is disconnected, the A end and the B end have no voltage difference.

In this embodiment, in response to a temperature change of the measured hot spot, the first temperature relay or the second temperature relay operates to cause a change in direction or magnitude of an output voltage (i.e., an AB terminal voltage) of the first signal conversion circuit, specifically, the following three conditions are included:

a1, when the temperature of the hot spot is lower than the first temperature, SW1 is open, the first signal conversion circuit is a one-way path, and the AB end voltage in the first signal conversion circuit is discontinuous direct current voltage by utilizing the principle of electromagnetic induction.

A2, when the temperature of the hot spot is not less than the first temperature and less than the second temperature, SW1 is closed, the first signal conversion circuit is a bidirectional path, and the AB voltage is an AC voltage.

A3, when the temperature of the hot spot to be measured is not less than the second temperature, SW2 is disconnected, the first signal conversion circuit is disconnected, and the AB terminal voltage is 0.

Further, the normally open relay and the normally closed relay have different operating temperatures, and according to the unidirectional conductive characteristic of the diode, the first signal conversion circuit provided by the application can trigger the operation of the temperature relay through different temperature thresholds (namely, the first temperature and the second temperature), and then change the voltage of the AB end in the first signal conversion circuit, as can be seen from the above-mentioned A1-A3, in the process of temperature rise, a voltage signal indicating temperature change can be obtained, and it can be understood that, by configuring the first temperature and the second temperature in advance, the temperature of the measured hot spot can be collected to be a voltage signal at a low temperature (less than the first temperature), a high temperature (not less than the first temperature and less than the second temperature), or an overheat (not less than the second temperature).

2. The structure and the working principle of the signal transmission circuit are as follows:

in this embodiment, the first end of the signal transmission circuit is connected to the end a through a wire and is denoted as the end C, and the second end of the signal transmission circuit is connected to the end B through a wire and is denoted as the end D. The signal transmission circuit comprises an equipotential circuit, a rectifying circuit, a current limiting circuit, an anti-interference circuit and a constant current circuit. The structure and the operation principle of each component circuit of the signal transmission circuit can be seen in the following 21-25.

21. The equipotential circuit comprises a preset conductor P, the difference value between the potential of the preset conductor and the potential of the measured hot spot is smaller than a preset value, namely, the potential of the preset conductor is equal to or close to the potential of the measured hot spot (the potential of the first measured hot spot and the potential of the second measured hot spot are the same by default), the preset conductor P is marked as an equipotential point, and the equipotential point can be an output line or an input line of the transformer or a tap arranged on the winding in advance or a small section of conducting wire connected with the winding. In this embodiment, the equipotential point is connected to the B terminal or the a terminal by a wire.

It should be noted that, in the detection circuit for the temperature of the transformer winding provided in the embodiment of the present application, the access position of the equipotential circuit is not limited, for example, an equipotential point may be connected to any position of the detection circuit for the temperature of the transformer winding by a conducting wire, so as to reduce the potential difference between the temperature relay and the detected hot spot, and reduce the requirement for insulation and voltage resistance, thereby reducing thermal resistance, reducing design difficulty and cost, improving temperature sensing accuracy, avoiding suspension of the detection circuit for the temperature of the transformer winding, and improving safety.

22. The rectifier circuit includes four diodes, as shown in fig. 1, a second diode D2, a third diode D3, a fourth diode D4, and a fifth diode D5.

Specifically, the first end of D2 is connected to the D terminal, the second end of D2 is connected to the second end of D3, the first end of D3 is connected to the C terminal, the second end of D4 is connected to the D terminal, the first end of D4 is connected to the first end of D5, and the second end of D5 is connected to the C terminal.

It can be understood that the rectifier circuit takes the AB terminal voltage as an input voltage, and takes the voltage difference between the second terminal (denoted as terminal E) of D3 and the first terminal (denoted as terminal F) of D5 as an output voltage, so as to convert the AB terminal voltage from an ac voltage to a dc voltage when the AB terminal voltage is an ac voltage. The specific working principle can be seen in the prior art.

23. The anti-interference circuit comprises a first anti-interference circuit and a second anti-interference circuit, wherein the first anti-interference circuit comprises a first resistor R1, the first end of R1 is connected to the D end, and the second end of R1 is connected to the C end. That is, the first resistor is connected in parallel with the first signal conversion circuit.

The second anti-interference circuit comprises a first capacitor C1, wherein a first end of a C1 is connected with a second end of D3, and a second end of a C1 is connected with a first end of D5.

It should be noted that the anti-interference circuit is used to filter noise, harmonic, and interference signals, and the anti-interference circuit may have another structure, for example, the second anti-interference circuit is a resistance-capacitance circuit composed of a capacitor and a resistor connected in parallel, and the specific working principle of the anti-interference circuit may be referred to in the prior art.

24. The current limiting circuit includes a second resistor R2.

Specifically, a first terminal of R2 is connected to the second terminal of D3, and a second terminal of R2 is connected to a first terminal (i.e., G terminal) of the second signal conversion circuit.

The current limiting circuit is intended to reduce the current flowing in the second signal conversion circuit and prevent the component in the circuit from being destroyed by an excessive current.

25. The constant current circuit comprises a third resistor R3, a fourth resistor R4, a voltage stabilizing diode D6 and a triode Q1.

Specifically, a first terminal of R3 is connected to a second terminal of R2, a second terminal of R3 is connected to a second terminal of D6, a first terminal of D6 is connected to a first terminal of D5, a first terminal of R4 is connected to a first terminal of D6, a second terminal of R4 is connected to a second terminal of Q1, a first terminal of Q1 is connected to a second terminal of D6, and a third terminal of Q1 is connected to a second terminal (i.e., H terminal) of the second signal conversion circuit.

In this embodiment, the type of the triode is an NPN triode, wherein a first end of the triode is a base, a second end is an emitter, and a third end is a collector.

The constant current circuit is used to limit the current flowing into the second signal conversion circuit within a set current value, and the purpose is to ensure that the current output by the signal transmission circuit is the optimal operating current required by the second signal conversion circuit, thereby improving reliability.

It should be further noted that, in order to implement the functions of the constant current circuit, the constant current circuit may further include various other optional specific structures, for example, a voltage regulator chip is used to replace a voltage regulator diode, which is not described in detail in this embodiment.

In summary, the input voltage signal of the signal transmission circuit provided in the embodiment of the present application is an AB terminal voltage, and the output voltage signal is a voltage signal after passing through the anti-interference circuit, the rectifier circuit, the current limiting circuit, and the constant current circuit.

3. The structure and the working principle of the second signal conversion circuit are as follows:

the second signal conversion circuit includes an electrical signal conversion device, as shown in fig. 1, the electrical signal conversion device is an electrical-to-optical transmitter HFBR1521, and the HFBR1521 includes a light emitting diode, which is denoted as a first light emitting diode L1, it should be noted that, in the circuit, the HFBR-1521 is equivalent to a light emitting diode including a special interface, an a interface of the HFBR-1521 is a G terminal, a K interface of the HFBR-1521 is an H terminal, and the first light emitting diode is turned on under a forward current, that is, when a voltage of the G terminal is greater than a voltage of the H terminal, the first light emitting diode is turned on.

It should be noted that the second signal conversion circuit converts the input voltage signal (i.e., the output voltage signal of the signal transmission circuit) into the optical signal through the electro-optical transducer. The specific structure of the electro-optical transducer can be seen in the prior art

In an optional application scenario, the second signal conversion circuit is connected with the control system, and aims to transmit the optical signal to the control system, convert the optical signal into an electrical signal through photoelectric conversion, and realize electrical isolation transmission.

According to the technical scheme, in the detection circuit of the transformer winding temperature provided by the embodiment of the application, the first signal conversion circuit is used for getting electricity and responding to temperature change to convert the temperature signal into the voltage signal, the signal transmission circuit is used for processing the voltage signal (including but not limited to rectification, current limiting and anti-interference) to obtain the optimized voltage signal, and the second signal conversion circuit is used for converting the optimized voltage signal into the optical signal.

In practical application, the first temperature is preset as a high temperature warning temperature, the second temperature is an overheat warning temperature, and the states of the first light emitting diode include at least three states according to different duty ratios, wherein the duty ratio is divided by lighting time ÷ (lighting time + non-lighting time) x 100%.

Specifically, when the duty ratio of the first light emitting diode is smaller than a preset first duty ratio, the temperature of the detected hot spot is judged to be smaller than a first temperature, and the winding temperature is normal. When the duty ratio of the first light emitting diode is larger than a preset second duty ratio, the temperature of the detected hot spot is judged to be larger than the first temperature and does not reach a second temperature, namely the temperature of the winding is in a high-temperature state. When the duty ratio of the first light emitting diode is 0, that is, the first light emitting diode is continuously extinguished, it can be judged that the temperature of the detected hot spot reaches a second temperature, that is, the temperature of the winding is in an overheat state.

It should be noted that specific values of the first duty ratio and the second duty ratio are related to an actual application scenario, and this embodiment does not limit this.

In this embodiment, an AB terminal voltage, an EF terminal voltage, and a GH terminal voltage in a circuit are exemplified by taking a first duty ratio of 50%, a second duty ratio of 70%, a temperature of a measured hot spot as T, a first temperature as 90 ℃, and a second temperature as 130 ℃.

Fig. 2a illustrates a waveform diagram of each voltage signal when T <90 ℃.

As shown in fig. 2a, when T <90 ℃, SW1 is turned off and SW2 is turned on, the voltage at AB terminal is an intermittent dc voltage, after passing through a rectifying circuit in a signal transmission circuit, the voltage waveform at EF terminal is identical to that at AB terminal, and after passing through a constant current circuit in the signal transmission circuit, the voltage waveform at GH terminal is a square wave or an approximate square wave with a duty ratio of 50% or less, the electro-optical transducer loses or gains power at a certain frequency, that is, the electro-optical transducer exhibits an on state and an off state alternately at a certain frequency. It should be noted that the specific duty ratio is related to the setting parameters of the capacitor C1, the resistor R2 and the constant current circuit, and is not a unique determination value.

FIG. 2b illustrates a waveform diagram for each voltage signal when 90 ℃ ≦ T <130 ℃.

As shown in fig. 2b, when T is greater than or equal to 90 ℃ and less than 130 ℃, SW1 is closed and SW2 is closed, the voltage at the AB terminal is alternating current voltage, the voltage at the EF terminal is direct current voltage after passing through a rectifying circuit in the signal transmission circuit, the waveform of the voltage is shown in fig. 2b, the waveform at the GH terminal is square wave with duty ratio greater than 70% after passing through a constant current circuit in the signal transmission circuit, it should be noted that, when the duty ratio is greater than 70%, the time for which the electro-optical transducer is lit is much longer than the time for which the electro-optical transducer is extinguished, the electro-optical transducer can also be considered as. It should be noted that the specific duty ratio is related to the setting parameters of the capacitor C1, the resistor R2 and the constant current circuit, and is not a unique determination value.

FIG. 2c illustrates waveforms of the voltage signals when T ≧ 130 ℃.

As shown in FIG. 2c, when T is equal to or higher than 130 ℃, SW2 is turned off, the voltage at AB terminal is 0, the voltage at EF terminal and the voltage at GH terminal are both 0, and the first LED is continuously turned off.

It should be noted that the first signal conversion circuit in fig. 1 is only an optional structure, and the relay properties (normally open or normally closed) of SW1 and SW2 are not limited in this embodiment, for example, the first temperature relay and the second temperature relay are both normally closed temperature relays, and when the first temperature is less than the second temperature, the measured hot spot temperature is less than the first temperature, SW1 is closed and SW2 is closed, and a voltage waveform diagram in the detection circuit of the transformer winding temperature is as shown in fig. 2 b. When the measured hot spot temperature is not less than the first temperature and less than the second temperature, the SW1 is opened and the SW2 is closed, the voltage waveform diagram of the detection circuit of the transformer winding temperature is shown in fig. 2a, the measured hot spot temperature is greater than the second temperature, the voltage at the AB end is 0, and the voltage waveform diagrams are shown in fig. 2 c.

It should be further noted that specific models of the components shown in fig. 1 are configured in advance according to actual needs, which is not limited in this embodiment, and the working principle of each component refers to the prior art, which is not described in detail in this embodiment.

According to the technical scheme, the electro-optical transmitter is driven by the iron core magnetic flux, and the beneficial effects of the electro-optical transmitter comprise but are not limited to:

the first signal conversion circuit and the first signal conversion circuit comprise temperature relays, and the first signal conversion circuit is arranged around an iron core of the transformer winding, so when the transformer is in electric operation, magnetic flux generated by the iron core generates an electromagnetic effect, voltage difference is generated at two ends (namely an end A and an end B) of the first signal conversion circuit, and when the temperature relays sense temperature change actions of the transformer winding, the temperature signals are converted into voltage signals. Furthermore, the second conversion circuit converts the voltage signal into an optical signal, and the first signal circuit can realize self-power-taking without external power supply, so that the safety is improved, and particularly, under a high-voltage application scene, the damage and even electric shock accidents of an electrical element caused by overlarge voltage difference between an external power supply device and a winding of a measured hot spot are avoided.

Second, compared with the method of sensing temperature by wrapping the insulating tube in the prior art, the temperature relay is directly placed at the measured hot spot of the transformer winding, so that the precision of temperature detection is greatly improved, and further, the cost of the circuit is reduced because the circuit does not need to use a temperature control tube for strengthening insulation.

And the AB terminal voltage changes in response to the temperature of the measured hot spot and the height relation between the first temperature and the second temperature (see particularly FIGS. 2 a-2 c), so that the EF terminal voltage waveform and the GH terminal voltage waveform correspondingly change, and the purpose of converting the changed temperature signal into the changed voltage signal is achieved.

Fourthly, because this circuit realizes converting temperature signal into the signal of telecommunication, converts the signal of telecommunication into optical signal again, further realizes passing through optic fibre isolation transmission to control system with the signal. Therefore, the electric connection between the temperature relay and the low-voltage control circuit is avoided through the self-power-taking and optical isolation of the transformer, and the safety is improved.

For example, the detection circuit for the temperature of the winding of the transformer may further include a control system (e.g., a controller) for receiving the level signal output by the electro-optical transducer and determining whether the transformer is overheated according to waveform information (waveform level, duty ratio, or the like) of the level signal, where the level signal is converted from the optical signal obtained by the second signal conversion circuit. It should be noted that, the Controller includes any one of a PLC (Programmable Logic Controller), an MCU (micro Controller Unit), a DSP (digital signal processor), and an FPGA (Field Programmable Gate Array), and the method for determining whether the transformer is overheated according to the waveform information of the level signal by the Logic device may refer to the prior art.

Therefore, the signal received by the controller is the level signal output by the electro-optical transmitter, and the controller directly collects the voltage signal instead of the prior art, so that the safety of the temperature detection circuit is improved.

It should be noted that the circuit shown in fig. 1 is only one specific structure of the detection circuit for the transformer winding temperature provided in the embodiment of the present application, and in other optional application scenarios, the detection circuit for the transformer winding temperature may also be in other optional specific structures.

Fig. 3 illustrates a specific structure diagram of another circuit for detecting the temperature of the transformer winding.

The specific structure of the transformer winding temperature detection circuit shown in fig. 3 is different from that of the transformer winding temperature detection circuit shown in fig. 1 in that:

in the circuit for detecting the temperature of the transformer winding shown in fig. 3, the signal transmission circuit includes an equipotential circuit, a rectifier circuit, and a constant current circuit. That is, the first terminal of R2 is connected directly to the second terminal of D3, without the current limiting circuitry of the immunity circuit.

It should be noted that the detection circuit for the transformer winding temperature shown in fig. 3 can also be implemented as follows:

the electro-optical transmitter is driven by utilizing the iron core magnetic flux to take electricity, the non-electrical connection between a detection circuit of the temperature of a transformer winding and a control system is realized, the safety is improved, the temperature relay can be directly preset on a hot spot coil, the temperature measurement precision is higher, and a temperature control tube for strengthening insulation is not needed, so the cost is reduced.

It should be further noted that the application scenario of the detection circuit for the transformer winding temperature provided in the embodiment of the present application is not limited to performing overheat detection on the phase-shifting transformer, and may be applied to other optional temperature measurement scenarios on the transformer winding. In addition, in an optional application scenario, the first signal conversion circuit in the detection circuit for the temperature of the transformer winding provided in the embodiment of the present application may also have other specific structures.

For example, an equipotential circuit, a rectifying circuit, a current limiting circuit, an anti-jamming circuit, and a constant current circuit are optional circuit structures. For another example, the first signal conversion circuit or the second signal conversion circuit may have other optional specific structures.

Fig. 4a illustrates yet another alternative specific structure of the first signal conversion circuit.

As shown in fig. 4a, the first signal conversion circuit includes a third temperature relay (abbreviated as SW 3). SW3 is normally closed temperature relay, the operating temperature is the third temperature, and is connected by wire SW3 and placed around the iron core of the transformer. The first terminal of SW3 is terminal A and the second terminal of SW3 is terminal B.

It will be appreciated that the transformer is energized and the core produces magnetic flux, and that at temperatures less than the third temperature, the terminal AB voltage is ac, and at temperatures up to the third temperature, SW3 is off and the terminal AB voltage is 0.

Fig. 4b illustrates yet another alternative specific structure of the first signal conversion circuit.

As shown in fig. 4B, the first signal conversion circuit includes a fifth resistor R5 and a fourth temperature relay SW4, a first terminal of R5 is connected to a first terminal of SW4, a second terminal of R5 is connected to a second terminal of SW4, a first terminal of SW4 is terminal a, and a first terminal of SW4 is terminal B. SW4 is normally open temperature relay, SW4 is the fourth temperature, and SW4 and R5 are connected by wires and placed around the iron core of the transformer.

It can be understood that the transformer is powered on, the iron core generates magnetic flux, when the temperature is lower than the fourth temperature, the voltage at the terminal AB is an alternating voltage at the two ends of R5, when the temperature reaches the fourth temperature, SW4 is closed, the terminal A is directly connected with the terminal B, and the voltage at the terminal A is 0.

In an optional application scenario, the signal transmission circuit in the detection circuit for the temperature of the transformer winding provided in the embodiment of the present application may also have other specific structures.

Fig. 5a illustrates yet another alternative specific structure of the signal transmission circuit.

As shown in fig. 5a, the signal transmission circuit includes a rectification circuit, an equipotential circuit, and a current limiting circuit.

In contrast to the signal transmission circuit shown in fig. 1, the signal transmission circuit shown in fig. 5a does not include a constant current circuit and an anti-interference circuit, and the first end of D5 of the rectifier circuit is directly connected to the F terminal. The structures of the rectification circuit, the equipotential circuit, and the current limiting circuit can be referred to the above embodiments.

It can be understood that the equipotential circuit is used for reducing the potential difference between the temperature relay and the conductor close to the hot point, the rectifying circuit is used for converting alternating-current voltage generated by the end A and the end B into direct-current voltage, and the current limiting circuit is used for limiting the current in the circuit, controlling the current of the light emitting diode and achieving the purpose of protecting the circuit.

Fig. 5b illustrates yet another alternative specific structure of the signal transmission circuit.

As shown in fig. 5b, the signal transmission circuit includes a rectifying diode D7, an equipotential circuit, and a current limiting resistor.

Referring to 21 in the above embodiment, taking the current limiting resistor R2 as an example, the R2 is connected in series between the terminal D and the terminal F, the first terminal of the rectifying diode D7 is connected to the terminal F, and the second terminal of the rectifying diode D7 is connected to the terminal E.

It can be understood that the equipotential circuit is used for reducing the potential difference between the temperature relay and the preset conductor, the current limiting circuit is used for limiting the current in the circuit to achieve the purpose of protecting the circuit, and the rectifier diode is used for limiting the current to flow into the F end from the E end only and flow out from the F end to protect the light emitting diode and improve the safety.

In an optional application scenario, the second signal conversion circuit in the detection circuit for the temperature of the transformer winding provided in the embodiment of the present application may also have other specific structures. For example, the present embodiment does not limit the specific structure of the electrical signal conversion device, the electrical signal conversion device is used for converting the voltage signal into other signals, the specific form of the other signals includes various types, such as optical signals or laser signals, and the specific structure of the electrical signal conversion device may be other structures besides the photoelectric transducer including the light emitting diode shown in fig. 1.

Optionally, the electrical signal conversion device comprises a first light emitting diode and a second light emitting diode.

Fig. 6 shows a specific structure of another detection circuit for detecting the temperature of the transformer winding, as shown in fig. 6, the signal conversion circuit includes an equipotential circuit and a current limiting resistor R2, the second signal conversion circuit includes two electro-optical transducers, it should be noted that, the first electro-optical transducer includes a first light emitting diode, an a interface of the first electro-optical transducer serves as a first end of the first electro-optical transducer, a K interface of the first electro-optical transducer serves as a second end of the first electro-optical transducer, the second electro-optical transducer includes a second light emitting diode, an a interface of the second electro-optical transducer serves as a first end of the second electro-optical transducer, a K interface of the second electro-optical transducer serves as a second end of the second electro-optical transducer, and the specific structure and the operation principle of the electro-optical transducers can refer to.

It should be noted that, the specific method for accessing the circuit by the current limiting resistor R2 may include multiple methods, and optionally, the current limiting resistor R2 may be located in the electrical signal conversion device, which is not described in detail in this embodiment.

In this embodiment, the interface a of the first electro-optical transducer is connected to the terminal C, and the interface K of the first electro-optical transducer is connected to the second terminal R2. The K interface of the second electro-optical transducer is connected with the C end, and the A interface of the first electro-optical transducer is connected with the second end of the R2. And, the first end of R2 is connected to the D terminal.

As shown in fig. 6, the output end of the signal output circuit is denoted as a GH end, when the voltage of the GH end is an alternating voltage, the duty ratio of the first light emitting diode is smaller than the first duty ratio, and the duty ratio of the second light emitting diode is smaller than the first duty ratio, and when the first electro-optical transducer is turned off, the second electro-optical transducer is turned on, and when the first electro-optical transducer is turned on, the second electro-optical transducer is turned off.

When the GH end is the direct-current voltage, the duty ratio of the first light-emitting diode is smaller than the first duty ratio, and the second light-emitting diode is continuously extinguished, or the duty ratio of the second light-emitting diode is smaller than the first duty ratio, and the first light-emitting diode is continuously extinguished.

In summary, the detection circuit for the transformer winding temperature provided by the embodiment of the present application is summarized as the schematic structural diagram shown in fig. 7, and as shown in fig. 7, the detection circuit for the transformer winding temperature includes a first signal conversion circuit and a second signal conversion circuit.

In this embodiment, the first signal conversion circuit includes a first temperature relay and a wire that are connected in series, the operating temperature of the first temperature relay is a preset first temperature, the first temperature relay is placed at a preset detected hot spot on the transformer winding, the first signal conversion circuit is placed around the iron core of the transformer winding, it should be noted that the number of turns of the wire around the iron core may be one or more, and this embodiment is not limited.

The first signal conversion circuit is used for collecting temperature signals and converting the temperature signals into voltage signals, wherein the temperature signals are the temperature of a detected hot spot, the voltage signals are the voltage difference of two ends of the temperature relay, and the voltage difference is generated by electromagnetic induction.

In this embodiment, the second signal conversion circuit at least includes an electrical signal conversion device, the electrical signal conversion device includes a first light emitting diode, a first end of the first light emitting diode is connected to a first end of the first signal conversion circuit, a second end of the first light emitting diode is connected to a second end of the first signal conversion circuit, specifically, the first end of the first light emitting diode is connected to a first end of the first temperature relay, and the second end of the first light emitting diode is connected to a second end of the first temperature relay. The second signal conversion circuit is used for converting the voltage signal into an optical signal, and the optical signal indicates the state of the light-emitting diode.

In fig. 7, only the light emitting diode provided in the electro-optical transducer is taken as an example of the first light emitting diode.

It will be appreciated that when the transformer is electrically operated, the core generates a magnetic flux (i.e. the main flux of the transformer).

If the first temperature relay is a normally open relay, when the temperature is lower than the first temperature, the first signal conversion circuit is open circuit, no current is generated, and the light-emitting diode is extinguished after power failure. When the temperature reaches (or exceeds) the first temperature, the first temperature relay is closed, the electromagnetic effect induces to generate current, the two ends of the temperature relay generate alternating voltage, and the light-emitting diode is in a flashing state.

If the first temperature relay is a normally closed relay, when the temperature is lower than the first temperature, the first signal conversion circuit is a passage, the electromagnetic effect induces to generate current, and alternating voltage is generated at two ends of the temperature relay, the light-emitting diode is in a flashing state, when the temperature reaches (or exceeds) the first temperature, the first temperature relay is disconnected, the first signal conversion circuit is an open circuit, no current is generated, and the light-emitting diode is extinguished in a power-off state.

It can be seen from the above technical solutions that the circuit for detecting the temperature of the transformer winding provided in the embodiments of the present application includes a first signal conversion circuit and a second signal conversion circuit, where the first signal conversion circuit includes a first temperature relay and a wire connected in series, and the first signal conversion circuit is disposed around an iron core of the transformer winding, so when the transformer is powered on and operated, magnetic flux generated by the iron core generates an electromagnetic effect, so that an alternating voltage is generated at two ends of the first signal conversion circuit when the first temperature relay is closed, and no voltage is generated at two ends of the first signal conversion circuit when the first temperature relay is opened, because the operating temperature of the first temperature relay is a preset first temperature and the first temperature relay is disposed at a preset detected hot spot on the transformer winding, the first temperature relay operates in response to the temperature of the detected hot spot, the voltage at two ends of the first temperature relay is changed, and therefore the temperature signal is converted into the voltage signal. And because the second signal conversion circuit comprises the electrical signal conversion device which comprises the first light emitting diode, it can be understood that the states of the first light emitting diode under different voltages are different, thereby realizing the conversion of the voltage signal into the optical signal, therefore, the circuit realizes the self-power supply of the first signal conversion circuit, converts the temperature signal into the voltage signal and further converts the voltage signal into the optical signal.

Finally, it should also be noted that, herein, relational terms such as first and second, and the like may be used solely to distinguish one entity or action from another entity or action without necessarily requiring or implying any actual such relationship or order between such entities or actions. Also, the terms "comprises," "comprising," or any other variation thereof, are intended to cover a non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements does not include only those elements but may include other elements not expressly listed or inherent to such process, method, article, or apparatus. Without further limitation, an element defined by the phrase "comprising an … …" does not exclude the presence of other identical elements in a process, method, article, or apparatus that comprises the element.

The embodiments in the present description are described in a progressive manner, each embodiment focuses on differences from other embodiments, and the same and similar parts among the embodiments are referred to each other.

The previous description of the disclosed embodiments is provided to enable any person skilled in the art to make or use the present application. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the generic principles defined herein may be applied to other embodiments without departing from the spirit or scope of the application. Thus, the present application is not intended to be limited to the embodiments shown herein but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.