CN215932107U - Poor contact detection circuit in capacitor leakage current and insulation resistance test - Google Patents
Poor contact detection circuit in capacitor leakage current and insulation resistance test Download PDFInfo
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- CN215932107U CN215932107U CN202122230713.5U CN202122230713U CN215932107U CN 215932107 U CN215932107 U CN 215932107U CN 202122230713 U CN202122230713 U CN 202122230713U CN 215932107 U CN215932107 U CN 215932107U
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Abstract
The utility model discloses a detection circuit for poor contact in a capacitor leakage current and insulation resistance test in the field of capacitor detection, which comprises a charging power supply PS, wherein the positive electrode of the charging power supply PS is connected with the positive electrode of a capacitor Cx to be detected, and the detection circuit is characterized in that: the tested capacitor Cx is connected with a poor contact detection circuit, and the poor contact detection circuit is connected with a sampling amplification conversion processing circuit through a current limiting resistor RL; according to the capacitance value of the capacitor to be detected, the appropriate alternating current frequency is matched, the alternating current impedance of the loop is ensured to be in a relatively low state, then the alternating current signal is quantized and calculated, and whether the loop has poor contact or an open circuit state can be conveniently distinguished; the measurement of the alternating-current impedance, the measurement of the leakage current and the insulation resistance are synchronously carried out, the transient loop state change caused by mechanical vibration can be avoided, the judgment reliability is high, and the method can be used for detecting the poor contact in the leakage current test of the capacitor.
Description
Technical Field
The utility model relates to a detection circuit in the field of electronic detection.
Background
In the measurement of the leakage current and insulation resistance of the capacitor, the measurement result is generally less than a predetermined upper limit as a good product. In production practice, particularly in automated testing, if the measurement circuit has poor contact or even open circuit, the measurement result is smaller or tends to 0, resulting in fatal error for judging the defective product as a qualified product. Most of the bad contacts are hidden and are difficult to be found manually in time, so that the phenomena of customer complaints, goods returning, rework and the like caused by measurement misjudgment are often caused, and the product quality and the economic benefit of enterprises are further influenced.
The current leakage current and insulation resistance measuring instrument in the market does not have the function of directly performing online real-time inspection on whether the measuring loop is in poor contact or not. Some instruments have the function of setting a lower limit, have no effect on poor contact, and only can roughly judge the complete open circuit state, and if the input end has electromagnetic interference (which often occurs in an industrial field) or the input stage of the instrument has accumulative zero drift, misjudgment is easy to occur.
SUMMERY OF THE UTILITY MODEL
The utility model aims to provide a poor contact detection circuit in capacitor leakage current and insulation resistance tests, which can conveniently distinguish whether a circuit has poor contact or an open circuit state.
In order to achieve the above object, the present invention provides a circuit for detecting poor contact in a capacitor leakage current and insulation resistance test, which comprises a charging power supply PS, wherein the positive electrode of the charging power supply PS is connected with the positive electrode of a capacitor Cx to be tested, and the circuit is characterized in that: the tested capacitor Cx is connected with a poor contact detection circuit, and the poor contact detection circuit is connected with a sampling amplification conversion processing circuit through a current limiting resistor RL.
Compared with the prior art, the utility model has the advantages that the AC impedance of the loop is ensured to be in a relatively low state by matching proper AC frequency according to the capacity value of the capacitor to be detected, and then the AC signal is quantized and calculated, so that whether the loop has poor contact or open circuit state can be conveniently distinguished; the measurement of the alternating-current impedance, the measurement of the leakage current and the insulation resistance are synchronously carried out, the transient loop state change caused by mechanical vibration can be avoided, the judgment reliability is high, and the method can be used for detecting the poor contact in the leakage current test of the capacitor.
As a further improvement of the utility model, the poor contact detection circuit comprises an AC alternating current signal source, a pin 1 and a pin 2 of the AC alternating current signal source are respectively connected with two ends of an isolation transformer B, the pin 1 of the AC alternating current signal source is grounded, one end of the isolation transformer B is connected with a cathode of a charging power supply PS, the other end of the isolation transformer B is connected with one end of a blocking capacitor C, the other end of the blocking capacitor C is respectively connected with a cathode of a capacitor Cx to be detected and one end of a current limiting circuit RL, the other end of the current limiting resistor RL is connected with a sampling amplification conversion processing circuit, so that in a parallel mode, direct current measurement (the current value is directly obtained by measuring current, the insulation resistance measurement is calculated by the ratio of the PS voltage value and the current value) flowing in the Cx can be simultaneously carried out due to the existence of the blocking capacitor C, the isolation transformer B does not form a loop for the direct current, so that the measurement of the direct current is not influenced.
As a further improvement of the utility model, the poor contact detection circuit comprises an AC alternating current signal source, a pin 1 and a pin 2 of the AC alternating current signal source are respectively connected with two ends of an isolation transformer B, the pin 1 of the AC alternating current signal source is grounded, one end of the isolation transformer B is connected with the negative electrode of a capacitor Cx to be detected, the other end of the isolation transformer B is connected with one end of a current limiting resistor RL, and the other end of the current limiting resistor RL is connected with a sampling amplification conversion processing circuit, so that direct current measurement (electric leakage) flowing through the Cx can be simultaneously carried out in a series mode (the electric leakage is measured)
Directly taking the current value by current measurement; insulation resistance measurement is calculated from the ratio of the PS voltage value and this current value). The primary circuit of the isolation transformer B does not form a loop for the direct current, so that the measurement of the direct current is not influenced.
As a further improvement of the present invention, the sampling, amplifying and converting processing circuit includes a protection diode D1, the anode of the protection diode D1 is connected to the other end of the current-limiting resistor RL and the cathode of the protection diode D2, the cathode of the protection diode D1 is grounded, the anode of the protection diode D2 is grounded, the cathode of the protection diode D2 is connected to the cathode of the amplifier OP, the anode of the amplifier OP is grounded, the cathode and the output end of the amplifier OP are connected to the two ends of the compensation capacitor C1, the compensation capacitor C1 is connected in parallel to the sampling resistor Rf, the output end of the amplifier OP is connected to the ADC circuit, the ADC circuit is connected to the microprocessor MCU, the microprocessor MCU is connected to the input/output controller IO, so that the current signal is converted into the voltage signal by the amplifier OP and the sampling resistor Rf and then converted into the digital quantity by the ADC circuit, and the microprocessor MCU outputs a processing result through the input/output control module IO after calculation processing.
Drawings
FIG. 1 is a schematic diagram of a leakage current and insulation resistance measuring circuit according to the present invention.
FIG. 2 is a schematic diagram of a sampling, amplifying, converting circuit according to the present invention.
FIG. 3 is a schematic diagram of a parallel contact failure detection circuit according to the present invention.
Fig. 4 is a schematic diagram of a series-connected poor contact detection circuit according to the present invention.
Detailed Description
The utility model is further described below with reference to the accompanying drawings:
example 1
The circuit for detecting poor contact in the leakage current and insulation resistance tests of the capacitor shown in fig. 1-3 comprises a charging power supply PS, wherein the positive electrode of the charging power supply PS is connected with the positive electrode of a capacitor Cx to be tested, the capacitor Cx to be tested is connected with a poor contact detection circuit, and the poor contact detection circuit is connected with a sampling amplification conversion processing circuit through a current-limiting resistor RL.
The poor contact detection circuit comprises an AC (alternating current) signal source, a pin 1 and a pin 2 of the AC signal source are respectively connected with two ends of an isolation transformer B, the pin 1 of the AC signal source is grounded, one end of the isolation transformer B is connected with the negative electrode of a charging power supply PS, the other end of the isolation transformer B is connected with one end of a blocking capacitor C, the other end of the blocking capacitor C is respectively connected with the negative electrode of a capacitor Cx to be detected and one end of a current limiting circuit RL, and the other end of the current limiting resistor RL is connected with a sampling amplification conversion processing circuit.
The sampling amplification conversion processing circuit comprises a protection diode D1, wherein the anode of the protection diode D1 is respectively connected with the other end of the current-limiting resistor RL and the cathode of the protection diode D2, the cathode of the protection diode D1 is grounded, the anode of the protection diode D2 is grounded, the cathode of the protection diode D2 is connected with the cathode of an amplifier OP, the anode of the amplifier OP is grounded, the cathode and the output end of the amplifier OP are respectively connected with the two ends of a compensation capacitor C1, the compensation capacitor C1 is connected with the sampling resistor Rf in parallel, the output end of the amplifier OP is connected with an ADC circuit, the ADC circuit is connected with a microprocessor MCU, and the microprocessor is connected with an input/output controller IO.
In the utility model, PS is a charging power supply, Cx is a measured capacitor, Rc is a contact resistor possibly existing in a measuring loop, RL is a current limiting resistor, a sampling amplification conversion processing circuit is an ACU circuit, wherein D1 and D2 are protection diodes, C1 is a compensation capacitor, an input current signal is converted into a voltage signal by an amplifier OP and a sampling resistor Rf, then the voltage signal is converted into a digital quantity by an ADC circuit, and then the digital quantity is calculated and processed by a microprocessor MCU and then a processing result is output by an input-output control module IO.
The specific connection relationship of the parallel circuit is as follows: PS is that a charging power supply is connected to the left side of a capacitor Cx to be measured, the right side of Cx is connected to the left side of a current-limiting resistor RL and also connected to the upper end of a blocking capacitor C, the right side of the current-limiting resistor RL is connected to the input of a sampling amplification conversion circuit, the negative pole of the charging power supply PS and the left side of the secondary side (the upper half) of an isolation transformer B are grounded together, and meanwhile, ACU is grounded with PS, the lower end of the blocking capacitor C is connected to the right side of the secondary side of the isolation transformer, and the primary side (the lower half) of the isolation transformer is driven by an alternating current signal source AC.
In parallel mode, the system consists of a PS charging power supply, an AC signal source, a B isolation transformer, a C blocking capacitor, an RL current limiting resistor and a sampling amplification conversion processing circuit, wherein Cx is a capacitor to be detected; AC generates an alternating current signal with adjustable frequency and amplitude and sends the alternating current signal into the primary of an isolation transformer B; the alternating voltage output by the secondary B is added between the point a and the ground wire through a blocking capacitor C; if the capacitor Cx to be measured is normally and reliably connected in the measurement loop, the AC voltage amplitude at the point a is reduced because the C capacity is smaller and the impedance of the Cx and the charging power supply (the internal resistance of the power supply output is lower) after being connected in series is lower, and the reduced amplitude is related to the capacity ratio of the Cx to the C; if the measured capacitor Cx is not connected to the measurement loop, or there is poor contact or even open circuit in the measurement loop, the input impedance of the sampling, amplifying and converting processing circuit connected to RL is very high, so the AC voltage at point a is relatively large. When the measuring loop is in an open circuit state, the voltage of the point a is approximately equal to the output voltage of the secondary B; when the measuring loop has poor contact, the voltage at the point a is related to the ratio of the contact resistance to the capacitance reactance of C. In any case, the ac voltage at point a enters the sampling, amplifying and converting circuit through RL for amplifying and converting, and then the total impedance of the loop is calculated by combining the capacitive reactance values of C and Cx to determine whether there is bad contact or even open circuit.
In the present invention,
example 2
As shown in fig. 4, the circuit for detecting poor contact in the capacitor leakage current and insulation resistance test includes an AC alternating current signal source, pin 1 and pin 2 of the AC alternating current signal source are respectively connected to two ends of an isolation transformer B, pin 1 of the AC alternating current signal source is grounded, one end of the isolation transformer B is connected to the negative electrode of a capacitor Cx to be tested, the other end of the isolation transformer B is connected to one end of a current limiting resistor RL, the other end of the current limiting resistor RL is connected to a sampling amplification conversion processing circuit, and the rest structures are not changed.
The specific connection relationship of the series circuit is as follows: the positive pole of the charging power supply PS is connected to the left side of the capacitor Cx to be measured, the right side of the Cx is connected to the left side of the secondary pole (the upper half) of the isolation transformer B, the right side of the secondary pole B is connected to the left side of the current-limiting resistor RL, the right side of the RL is connected to the input of the sampling amplification conversion circuit unit ACU, the negative pole of the charging power supply PS and the ground wire of the ACU are in common ground, and the primary pole of the isolation transformer is driven by the alternating current signal source AC.
In the series mode, the circuit consists of a PS charging power supply, an AC signal source, a B isolation transformer, an RL current-limiting resistor and a sampling amplification conversion processing circuit, wherein Cx is a capacitor to be detected. AC generates an alternating current signal with adjustable frequency and amplitude and sends the alternating current signal into the primary of an isolation transformer B; the AC voltage output by the secondary B is superposed between Cx and RL in series. If the measured capacitor Cx is normally and reliably connected in the measurement loop, because the secondary resistance of B is very small, and the impedance of Cx and the charging power supply (the internal resistance of the power supply output is very low) after being connected in series is very low, the alternating voltage induced by the secondary side of the isolation transformer B can form a larger alternating current to enter the sampling amplification conversion processing circuit through RL. If the measured capacitor Cx is not connected to the measurement loop or the measurement loop has poor contact or even an open circuit state, the alternating current passing through the RL becomes small, and the reduced amplitude is related to the size of the contact resistance in the loop; if the measuring loop has an open circuit, the alternating current is 0. In any case, the AC current enters the ACU circuit unit through the RL to be amplified and converted, and then the total impedance of the loop is calculated by combining the capacitive reactance value of the Cx, so as to judge whether the contact failure exists or not, and even the open circuit exists.
When the circuit works, the circuit in the parallel mode can be matched with a signal processing circuit in the ACU circuit by adjusting the capacity of the blocking capacitor C, so that the circuit design is simplified, but the sampling, amplifying, converting and processing circuit is required to have higher input internal resistance; the series mode has no requirement on the input internal resistance of the ACU circuit, so that the applicability is wider; but the sampling, amplifying and converting processing circuit is relatively complex; however, the following beneficial effects can be achieved by the circuit in any mode: according to the capacitance value of the capacitor to be detected, the appropriate alternating current frequency is matched, the alternating current impedance of the loop is ensured to be in a relatively low state, then the alternating current signal is quantized and calculated, and whether the loop has poor contact or an open circuit state can be conveniently distinguished. The measurement of the alternating current impedance, the measurement of the leakage current and the insulation resistance are synchronously carried out, the transient loop state change caused by mechanical vibration can be avoided, and the judgment reliability is high. The transformer is used for isolating the alternating current signal, so that the measurement of leakage current and insulation resistance is not influenced at all, and the measurement accuracy under a normal state is ensured. The open circuit problems caused by poor contact caused by dirt of the capacitor lead and the jig, incomplete clamping of the internal broken line of the capacitor and the jig, broken line of a test cable, even falling off of a connecting line of a charging power supply and the like can be effectively avoided.
The utility model is also applicable to capacitor open circuit testing. In practical applications, the polarities of the charging power source and the positive and negative electrodes of the measured capacitance Cx (for the polar electrolytic capacitor) may be opposite to those shown in fig. 1, 3 and 4, as required by the circuit design.
The present invention is not limited to the above embodiments, and based on the technical solutions of the present disclosure, those skilled in the art can make some substitutions and modifications to some technical features without creative efforts according to the disclosed technical contents, and these substitutions and modifications are all within the protection scope of the present invention.
Claims (4)
1. The utility model provides a bad detection circuitry of contact in condenser leakage current and insulation resistance test, includes charging power supply PS, charging power supply PS's positive pole links to each other with the positive pole of surveyed capacitor Cx, its characterized in that: the tested capacitor Cx is connected with a poor contact detection circuit, and the poor contact detection circuit is connected with a sampling amplification conversion processing circuit through a current limiting resistor RL.
2. The circuit for detecting poor contact in capacitor leakage current and insulation resistance test as claimed in claim 1, wherein: the poor contact detection circuit comprises an AC (alternating current) signal source, a pin 1 and a pin 2 of the AC signal source are respectively connected with two ends of an isolation transformer B, the pin 1 of the AC signal source is grounded, one end of the isolation transformer B is connected with the negative electrode of a charging power supply PS, the other end of the isolation transformer B is connected with one end of a blocking capacitor C, the other end of the blocking capacitor C is respectively connected with the negative electrode of a capacitor Cx to be detected and one end of a current limiting circuit RL, and the other end of the current limiting resistor RL is connected with a sampling amplification conversion processing circuit.
3. The circuit for detecting poor contact in capacitor leakage current and insulation resistance test as claimed in claim 1, wherein: the poor contact detection circuit comprises an AC (alternating current) signal source, a pin 1 and a pin 2 of the AC signal source are respectively connected with two ends of an isolation transformer B, the pin 1 of the AC signal source is grounded, one end of the isolation transformer B is connected with the negative electrode of a capacitor Cx to be detected, the other end of the isolation transformer B is connected with one end of a current limiting resistor RL, and the other end of the current limiting resistor RL is connected with a sampling amplification conversion processing circuit.
4. A circuit for detecting a contact failure in a capacitor leakage current and insulation resistance test according to any one of claims 1 to 3, wherein: the sampling amplification conversion processing circuit comprises a protection diode D1, wherein the anode of the protection diode D1 is connected with the other end of the current-limiting resistor RL and the cathode of the protection diode D2 respectively, the cathode of the protection diode D1 is grounded, the anode of the protection diode D2 is grounded, the cathode of the protection diode D2 is connected with the cathode of an amplifier OP, the anode of the amplifier OP is grounded, the cathode and the output end of the amplifier OP are connected with the two ends of a compensation capacitor C1 respectively, the compensation capacitor C1 is connected with a sampling resistor Rf in parallel, the output end of the amplifier OP is connected with an ADC circuit, the ADC circuit is connected with a microprocessor MCU, and the microprocessor MCU is connected with an input/output controller IO.
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| Application Number | Priority Date | Filing Date | Title |
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| CN202122230713.5U CN215932107U (en) | 2021-09-15 | 2021-09-15 | Poor contact detection circuit in capacitor leakage current and insulation resistance test |
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| CN202122230713.5U CN215932107U (en) | 2021-09-15 | 2021-09-15 | Poor contact detection circuit in capacitor leakage current and insulation resistance test |
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Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN114660504A (en) * | 2022-04-08 | 2022-06-24 | 东方电气集团东方电机有限公司 | Detection method and device for insulation monitoring loop, electronic equipment and storage medium |
| CN114993120A (en) * | 2022-04-24 | 2022-09-02 | 上海芯飏科技有限公司 | Detection circuit and method for leakage current of ignition capacitor of electronic detonator |
| CN116699463A (en) * | 2023-07-28 | 2023-09-05 | 珠海禅光科技有限公司 | MLCC capacitor leakage current measuring method, device, control device and medium |
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2021
- 2021-09-15 CN CN202122230713.5U patent/CN215932107U/en active Active
Cited By (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN114660504A (en) * | 2022-04-08 | 2022-06-24 | 东方电气集团东方电机有限公司 | Detection method and device for insulation monitoring loop, electronic equipment and storage medium |
| CN114993120A (en) * | 2022-04-24 | 2022-09-02 | 上海芯飏科技有限公司 | Detection circuit and method for leakage current of ignition capacitor of electronic detonator |
| CN114993120B (en) * | 2022-04-24 | 2023-10-31 | 上海芯飏科技有限公司 | Detection circuit and method for leakage current of ignition capacitor of electronic detonator |
| CN116699463A (en) * | 2023-07-28 | 2023-09-05 | 珠海禅光科技有限公司 | MLCC capacitor leakage current measuring method, device, control device and medium |
| CN116699463B (en) * | 2023-07-28 | 2024-02-06 | 珠海禅光科技有限公司 | MLCC capacitor leakage current measuring method, device, control device and medium |
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