A leakage detection alarm system for an induction electric stove
By employing sampling circuits, control circuits, and display circuits in the induction furnace, combined with components such as current transformers and Hall sensors, accurate detection and alarm of leakage current in the induction furnace are achieved, solving the problem of poor reliability in existing systems and ensuring stable and safe operation of the equipment.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- SHANGHAI ZHAOLI ELECTRICAL APPLIANCE MFG CO LTD
- Filing Date
- 2025-04-30
- Publication Date
- 2026-06-02
AI Technical Summary
Existing induction furnace leakage detection and alarm systems have poor reliability and cannot accurately determine whether the induction furnace is leaking electricity, which may lead to unstable operation or endanger personnel safety.
The system employs sampling circuits, control circuits, and display circuits. It collects leakage current signals in real time through current transformers, Hall sensors, and isolation transmitters. It uses a current controller to determine the leakage current value and combines a test circuit to periodically simulate leakage current conditions, thereby achieving accurate leakage current detection and alarm.
It enables accurate detection and timely alarm of leakage current in induction furnaces, ensuring stable equipment operation and improving safety.
Smart Images
Figure CN224317759U_ABST
Abstract
Description
Technical Field
[0001] This application relates to the technical field of metallurgical equipment testing, and in particular to a leakage current detection alarm system for induction furnaces. Background Technology
[0002] An induction furnace is a high-efficiency smelting device that melts magnetically conductive charge within the furnace chamber using the principle of electromagnetic induction. It is commonly used in steel smelting enterprises. During operation, induction furnaces may experience electrical system leakage due to changes in operating conditions. Possible causes of leakage include: prolonged use leading to aging of insulating components and decreased insulation performance; thinning of the furnace lining, reducing insulation resistance; changes in the cooling water quality for electrical components, increasing conductivity; and others. These factors can cause induction furnace leakage, potentially leading to instability in operation or damage to components. In more dangerous situations, it can even endanger the lives of operators.
[0003] Current leakage current detection alarm systems generally rely on manual, intermittent observation and experience-based judgment based on fluctuations in the voltage and current of the intermediate frequency power supply. However, both of these methods have poor reliability.
[0004] In view of the above-mentioned related technologies, since the existing technology cannot accurately determine whether an induction furnace is leaking current, this application provides a leakage detection alarm system for induction furnaces. Utility Model Content
[0005] To more accurately determine whether an induction furnace is leaking electricity, this application provides a leakage detection alarm system for induction furnaces.
[0006] This application provides a leakage current detection and alarm system for induction furnaces, which adopts the following technical solution:
[0007] A leakage current detection and alarm system for an induction furnace includes a sampling circuit and a control circuit. The input terminal of the sampling circuit is electrically connected to the sampling terminal of a resonant load, and the output terminal of the sampling circuit is electrically connected to the input terminal of the control circuit. The output terminal of the control circuit is electrically connected to a subsequent alarm circuit. The control circuit includes a current controller, the input terminal of which is electrically connected to the output terminal of the sampling circuit, and the output terminal of the current controller is electrically connected to the subsequent alarm circuit.
[0008] By adopting the above technical solution, the sampling circuit collects the leakage current signal of the resonant load in real time, and the leakage current signal is simultaneously transmitted to the control circuit and the display circuit. In the control circuit, after the current controller receives the test leakage current signal, if it determines that the test leakage current value is greater than the alarm current value, an alarm signal is generated; if it determines that the test leakage current value is less than the alarm current value, no alarm signal is generated. This can more accurately determine whether the induction furnace has leakage current.
[0009] Preferably, the sampling circuit includes a grounding line, a current transformer CTCT, a Hall sensor H, and an isolation transmitter. The primary side of the current transformer CT is connected to the grounding line, and the secondary side of the current transformer CT is connected to the first sensing terminal of the Hall sensor H. The output terminal of the Hall sensor H is electrically connected to the input terminal of the isolation transmitter, and the output terminal of the isolation transmitter is electrically connected to the input terminal of the control circuit.
[0010] By adopting the above technical solution, during operation, the leakage current signal on the grounding line is obtained through the current transformer. If the resonant load has no leakage, there is almost no leakage current flowing through the grounding line. If the resonant load has leakage, that is, the resistance value of the equivalent leakage resistor decreases, and there is leakage current flowing through the grounding line. According to the principle of current conservation, the grounding terminal will flow into the resonant load with a reverse leakage current of equal value to the leakage current. This reverse leakage current is used to represent the leakage current of the resonant load to ground.
[0011] Preferably, the input signal of the resonant load is connected to the voltage output of the intermediate frequency power supply VCC1, and the sampling end of the resonant load is grounded through a dedicated grounding line.
[0012] By adopting the above technical solution, the voltage output terminal of the intermediate frequency power supply VCC1 can provide a stable intermediate frequency power supply for the resonant load; the sampling terminal of the resonant load is grounded through a dedicated grounding line, providing an accurate and stable reference potential for the signal detection and processing of the load.
[0013] Preferably, the current controller is electrically connected to both the isolation transmitter and the operating power supply VCC2, wherein the operating power supply VCC2 is a power signal that provides stable power to the current controller.
[0014] By adopting the above technical solution, the isolation transmitter provides an isolation signal for the current controller, and the operating power supply provides a continuous and stable power supply for the control circuit.
[0015] Preferably, the system further includes a display circuit, wherein the input terminal of the display circuit is electrically connected to the output terminal of the sampling circuit, and the output terminal of the display circuit is electrically connected to the input terminal of the sampling circuit.
[0016] By adopting the above technical solution, the display circuit presents the magnitude of the leakage current, making it convenient for operators to obtain the leakage status of the resonant load in a timely manner.
[0017] Preferably, the display circuit includes an ammeter A, the two ends of which are electrically connected to the output terminal of the sampling circuit.
[0018] By adopting the above technical solution, the leakage current flows from the sampling circuit to the display circuit, and the display circuit displays the magnitude of the leakage current, making it convenient for operators to obtain the leakage status of the resonant load in a timely manner.
[0019] Preferably, it also includes a test circuit, which is electrically connected to the sampling circuit.
[0020] By adopting the above technical solution, the test circuit can periodically simulate leakage current and test the operation status of the entire system by injecting test leakage current. Once an abnormality is found in the resonant load, an alarm can be issued in time to prompt the operator to perform corresponding maintenance and adjustment.
[0021] Preferably, the test circuit includes a test transformer T, a current-limiting resistor R2, and a test button SB. One end of the primary side of the test transformer T is electrically connected to the positive terminal of the test power supply VCC3, and the other end of the primary side of the test transformer T is electrically connected to the negative terminal of the test power supply VCC3. One end of the secondary side of the test transformer T is electrically connected to one end of the current-limiting resistor R2; the other end of the current-limiting resistor R2 is electrically connected to one end of the test button SB, and the other end of the test button SB is electrically connected to the other end of the secondary side of the test transformer T; the secondary side of the test transformer T is connected to the second sensing terminal of the sampling circuit.
[0022] By adopting the above technical solution, when the test button is pressed, the test circuit is connected, and a test leakage current appears on the secondary side of the test transformer T. The test leakage current flows to the current controller through the sampling circuit. If the leakage current detection alarm system is working normally, after the current controller receives the test leakage current signal, if it determines that the test leakage current value is greater than the alarm current value, an alarm signal will be generated; if it determines that the test leakage current value is less than the alarm current value, no alarm signal will be generated.
[0023] In summary, this application includes at least one of the following beneficial technical effects:
[0024] 1. The sampling circuit collects leakage current signals in the grounding line in real time. The leakage current signals are simultaneously transmitted to the control circuit and the display circuit. The control circuit analyzes and processes the leakage current signals according to preset parameters. If the leakage current signal is greater than the preset parameters, an alarm signal is issued. The display circuit displays the magnitude of the leakage current, which makes it convenient for operators to obtain the leakage current status of the resonant load in a timely manner and can accurately determine whether the induction furnace has leakage current.
[0025] 2. During operation, the leakage current signal on the grounding line is obtained through the current transformer. If the resonant load has no leakage current, there is almost no leakage current flowing through the grounding line. If the resonant load has leakage current, that is, the resistance value of the equivalent leakage current resistor decreases, and there is leakage current flowing through the grounding line. According to the principle of current conservation, the grounding terminal will flow into the resonant load with a reverse leakage current of the same value as the leakage current. This reverse leakage current is used to represent the leakage current of the resonant load to ground.
[0026] 3. When the test button is pressed, the test circuit is connected, and a test leakage current appears on the secondary side of the test transformer T. The test leakage current flows to the current controller through the sampling circuit. If the leakage current detection alarm system is working normally, after the current controller receives the test leakage current signal, if it determines that the test leakage current value is greater than the alarm current value, an alarm signal will be generated; if it determines that the test leakage current value is less than the alarm current value, no alarm signal will be generated. Attached Figure Description
[0027] Figure 1 This is the circuit diagram of this application.
[0028] Reference numerals in the attached diagram: 1. Sampling circuit; 2. Control circuit; 3. Display circuit; 4. Test circuit. Detailed Implementation
[0029] The following is in conjunction with the appendix Figure 1 This application will be described in further detail.
[0030] In practical applications of induction furnaces, a medium-frequency power supply device is typically used to generate the medium-frequency power supply VCC1. First, three-phase AC power is connected and rectified to DC power. The DC power then enters an inverter circuit, where it is inverted back into medium-frequency AC power, thus generating the medium-frequency power supply VCC1. The voltage output from VCC1 excites a resonant load. The positive and negative terminals of VCC1 are electrically connected to the two ends of the resonant load. Changes in the insulation level of the resonant load to ground cause changes in leakage current, which becomes a key indicator for leakage current detection. Specifically, the resonant load includes multiple capacitor banks connected in parallel and an inductor L. Each capacitor bank includes two capacitors C connected in series, with the sampling terminal located at the midpoint between the two series-connected capacitors C.
[0031] The intermediate frequency power supply VCC1 is connected to both ends of the resonant load. The leakage current detection and alarm system is responsible for the energy conversion of the induction furnace, which is the electrical system to be detected for leakage current. For ease of analysis, the insulation level of the leakage current detection and alarm system to ground is represented by equivalent leakage current resistors R1 and R2. One end of the equivalent leakage current resistor R1 is connected to the positive terminal of the intermediate frequency power supply VCC1, and the other end is grounded; one end of the equivalent leakage current resistor R2 is connected to the negative terminal of the intermediate frequency power supply VCC1, and the other end is grounded.
[0032] When the insulation performance of the leakage current detection alarm system is good, i.e., the insulation level to ground is high, the resistance values of the equivalent leakage current resistors R1 and R2 are relatively large. According to Ohm's law I=U / R (where I is the current, U is the voltage, and R is the resistance), with a constant output voltage of the intermediate frequency power supply VCC1, the larger the resistance values of the equivalent leakage current resistors R1 and R2, the smaller the leakage current. Conversely, when the insulation level decreases due to various reasons (such as aging of insulating components, thinning of the furnace lining, etc.), the resistance values of the equivalent leakage current resistors R1 and R2 decrease, and the leakage current increases. Therefore, the insulation level to ground of the leakage current detection alarm system can be inferred by detecting the magnitude of the leakage current.
[0033] This application discloses a leakage current detection and alarm system for induction furnaces.
[0034] Reference Figure 1 A leakage current detection alarm system for an induction furnace includes a sampling circuit 1, a control circuit 2, a display circuit 3, and a test circuit 4. The input terminal of the sampling circuit 1 is electrically connected to the sampling terminal of the resonant load, and the output terminal of the sampling circuit 1 is electrically connected to the input terminal of the control circuit 2. The output terminal of the control circuit 2 is electrically connected to the subsequent alarm circuit. The sampling circuit 1 is electrically connected to the display circuit 3. The test circuit 4 is electrically connected to the sampling circuit 1. The control circuit 2 includes a current controller, the input terminal of which is electrically connected to the output terminal of the sampling circuit, and the output terminal of the current controller is electrically connected to the subsequent alarm circuit.
[0035] During operation, sampling circuit 1 collects leakage current signals from the resonant load in real time. The leakage current signals are simultaneously transmitted to control circuit 2 and display circuit 3. In control circuit 2, after receiving the test leakage current signal, the current controller generates an alarm signal if it determines that the test leakage current value is greater than the alarm current value; otherwise, it does not generate an alarm signal. Display circuit 3 displays the magnitude of the leakage current, allowing operators to promptly obtain the leakage status of the resonant load. Test circuit 4 can periodically simulate leakage conditions by injecting test leakage current to verify the operation of the entire system. Once leakage is detected in the circuit, it can promptly issue an alarm to prompt operators to perform maintenance.
[0036] Sampling circuit 1 includes a grounding line, a current transformer (CT), a Hall sensor (H), and an isolation transmitter. The primary side of the current transformer (CT) is connected to the grounding line, and the secondary side of the current transformer (CT) is connected to the first sensing terminal of the Hall sensor (H). The output terminal of the Hall sensor (H) is electrically connected to the input terminal of the isolation transmitter. The output terminal of the isolation transmitter is electrically connected to the input terminal of the control circuit 2. The isolation transmitter is electrically connected to the display circuit 3.
[0037] The input signal of the resonant load is connected to the voltage output of the intermediate frequency power supply VCC1, and the sampling end of the resonant load is grounded through a dedicated grounding line.
[0038] Display circuit 3 includes ammeter A, which is electrically connected to the isolation transmitter. Ammeter A is used to display the leakage current value.
[0039] During operation, the sampling terminal of the resonant load is grounded as a zero-potential reference for the resonant load. The leakage current signal on the grounding line is obtained through the current transformer (CT). If the resonant load has no leakage current, almost no leakage current flows through the grounding line. If the resonant load leaks current, i.e., the resistance values of the equivalent leakage resistor R1 and the equivalent leakage resistor R2 decrease, the resonant load leaks to ground. According to the principle of current conservation, a reverse leakage current of equal value will flow into the resonant load from the grounded end of the grounding line. This reverse leakage current represents the ground leakage current of the leakage current detection alarm system. This ground leakage current is output to the Hall sensor H through the current transformer (CT). The Hall sensor H converts the ground leakage current into a standard signal and outputs the standard signal to the control circuit 2 and the display circuit 3.
[0040] The isolation transmitter and the working power supply VCC2 are electrically connected to the current controller. The working power supply VCC2 is the power signal that provides stable power to the current controller. An alarm current is set in the current controller. If the leakage current to ground exceeds the alarm current set on the current controller, the alarm auxiliary point of the current controller closes and an alarm signal is generated. If the leakage current to ground does not exceed the set alarm current, the alarm auxiliary point of the current controller opens and no alarm signal is generated.
[0041] Test circuit 4 includes a test transformer T, a current-limiting resistor R2, and a test button SB. One end of the primary side of test transformer T is electrically connected to the positive terminal of test power supply VCC3, and the other end of the primary side of test transformer T is electrically connected to the negative terminal of test power supply VCC3. One end of the secondary side of test transformer T is electrically connected to one end of current-limiting resistor R2; the other end of current-limiting resistor R2 is electrically connected to one end of test button SB, and the other end of test button SB is electrically connected to the other end of the secondary side of test transformer T. The secondary side of test transformer T is connected to the second sensing terminal of Hall sensor H. Test power supply VCC3 provides power to the primary side of test transformer T.
[0042] When the test button SB is pressed, test circuit 4 is activated, and a test leakage current appears on the secondary side of the test transformer T. The test leakage current flows to the current controller through the Hall sensor H. If the test circuit is working properly, after receiving the test leakage current signal, the current controller will generate an alarm signal if it determines that the test leakage current value is greater than the alarm current value; otherwise, it will not generate an alarm signal.
[0043] The implementation principle of this application embodiment is as follows: After the resonant load experiences leakage, the current transformer (CT) acquires the leakage signal and transmits it to the Hall sensor (H). The Hall sensor (H) converts the leakage current to ground into a standard signal and outputs the standard signal to the current controller. If the leakage current to ground exceeds the alarm current set on the current controller, the alarm auxiliary point of the current controller closes, generating an alarm signal. If the leakage current to ground does not exceed the alarm current set on the current controller, the alarm auxiliary point of the current controller opens, and no alarm signal is generated.
[0044] The above are all preferred embodiments of this application, and are not intended to limit the scope of protection of this application. Therefore, all equivalent changes made in accordance with the structure, shape and principle of this application should be covered within the scope of protection of this application.
Claims
1. A leakage current detection and alarm system for induction furnaces, characterized in that, It includes a sampling circuit (1) and a control circuit (2); the input terminal of the sampling circuit (1) is electrically connected to the sampling terminal of the resonant load, the output terminal of the sampling circuit (1) is electrically connected to the input terminal of the control circuit (2), and the output terminal of the control circuit (2) is electrically connected to the subsequent alarm circuit; the control circuit (2) includes a current controller, the input terminal of the current controller is electrically connected to the output terminal of the sampling circuit (1), and the output terminal of the current controller is electrically connected to the subsequent alarm circuit.
2. The leakage current detection and alarm system for induction furnaces according to claim 1, characterized in that, The sampling circuit (1) includes a grounding line, a current transformer (CT), a Hall sensor (H), and an isolation transmitter. The primary side of the current transformer (CT) is connected to the grounding line, and the secondary side of the current transformer (CT) is connected to the first sensing terminal of the Hall sensor (H). The output terminal of the Hall sensor (H) is electrically connected to the input terminal of the isolation transmitter, and the output terminal of the isolation transmitter is electrically connected to the input terminal of the control circuit (2).
3. The leakage current detection and alarm system for induction furnaces according to claim 1, characterized in that, The input signal of the resonant load is connected to the voltage output of the intermediate frequency power supply VCC1, and the sampling end of the resonant load is grounded through a dedicated grounding line.
4. The leakage current detection and alarm system for induction furnaces according to claim 2, characterized in that, The current controller is electrically connected to the isolation transmitter and the working power supply VCC2, respectively. The working power supply VCC2 is a power signal that provides stable power to the current controller.
5. The leakage current detection and alarm system for an induction furnace according to claim 1, characterized in that, It also includes a display circuit (3), the input terminal of which is electrically connected to the output terminal of the sampling circuit (1), and the output terminal of the display circuit (3) is electrically connected to the input terminal of the sampling circuit (1).
6. The leakage current detection and alarm system for induction furnaces according to claim 5, characterized in that, The display circuit (3) includes an ammeter A, the two ends of which are electrically connected to the output of the sampling circuit (1).
7. The leakage current detection and alarm system for induction furnaces according to claim 1, characterized in that, It also includes a test circuit (4), which is electrically connected to the sampling circuit (1).
8. The leakage current detection and alarm system for induction furnaces according to claim 7, characterized in that, The test circuit (4) includes a test transformer T, a current-limiting resistor R2, and a test button SB. One end of the primary side of the test transformer T is electrically connected to the positive terminal of the test power supply VCC3, and the other end of the primary side of the test transformer T is electrically connected to the negative terminal of the test power supply VCC3. One end of the secondary side of the test transformer T is electrically connected to one end of the current-limiting resistor R2. The other end of the current-limiting resistor R2 is electrically connected to one end of the test button SB, and the other end of the test button SB is electrically connected to the other end of the secondary side of the test transformer T. The secondary side of the test transformer T is connected to the second sensing terminal of the sampling circuit (1).