CN117310561A - Electrolytic capacitor test positive and negative connection detection method based on leakage current detection - Google Patents

Abstract

The invention discloses a positive and negative connection detection method for an electrolytic capacitor test based on leakage current detection, which belongs to the technical field of capacitor tests and comprises the following steps: establishing a test circuit; the test circuit is used for installing a test ammeter or voltmeter according to the capacitance value of the capacitor; switching on a test circuit switch, and reading current value record data on an ammeter; switching on a test circuit switch, reading voltage value record data on a voltmeter, and calculating a current value according to ohm's law; changing the positive and negative electrode connection mode of the electrolytic capacitor, measuring the current value or the voltage value again and recording data; checking the result; the method has the advantages of high detection and judgment accuracy, simplicity in operation and the like, other problems caused by forward and reverse connection errors can be avoided, and capacitors with different capacitance values can be tested by using an ammeter or a voltmeter respectively, so that the method is wide in adaptability.

Description

A positive and reverse connection detection method for electrolytic capacitor testing based on leakage current detection

Technical field

The invention relates to the technical field of capacitor testing, specifically a positive and negative connection detection method for electrolytic capacitor testing based on leakage current detection.

Background technique

Electrolytic capacitor is an electronic component widely used in circuits. It consists of two electrodes (positive and negative) and an electrolyte, usually a liquid or gel-like substance. The electrodes of an electrolytic capacitor are usually made of metal foil and are separated from the electrolyte. Typical electrolytes include aluminum sulfate, potassium sulfate, etc. When an electric field is present in the electrolyte, a potential difference is created between the positive and negative electrodes, causing the capacitor to store charge. This potential difference can be created by connecting a capacitor to a power source. Compared to other types of capacitors, electrolytic capacitors are characterized by relatively high capacitance and high operating voltage. Because they can store large amounts of charge, electrolytic capacitors are often used in circuits that require large-capacity energy storage, such as power supply filtering, DC power supply voltage stabilization, etc. However, electrolytic capacitors also have some limitations. Due to their internal structure, electrolytic capacitors have fixed polarity and are not suitable for use in AC circuits.

The difference between positive and negative electrolytic capacitor connections lies in the polarity of the two terminals. If the positive terminal is connected to the positive terminal and the negative terminal is connected to the negative terminal, the electrolytic capacitor is connected positively. And if the positive pole is connected to the negative pole and the negative pole is connected to the positive pole, the electrolytic capacitor is reverse-connected. Electrolytic capacitors are one of the commonly used test components in testing equipment. However, in the actual testing process, due to human operating errors or component quality problems, positive and reverse connection errors sometimes occur. In the existing technology, special leakage capacitors are generally used. A current tester is used for testing, but when there is no leakage current tester, a quick test method is needed.

Contents of the invention

The purpose of the present invention is to provide a positive and reverse connection detection method for electrolytic capacitor testing based on leakage current detection, so as to solve the problems raised in the above background technology.

In order to achieve the above objects, the present invention provides the following technical solutions:

A forward and reverse connection detection method for electrolytic capacitor testing based on leakage current detection, including the following steps:

S1. Establish a test circuit;

S2. In the test circuit, install a test ammeter or voltmeter according to the capacitance value of the capacitor;

S3. Turn on the test circuit switch and read the current value record data on the ammeter;

S4. Turn on the test circuit switch, read the voltage value record data on the voltmeter, and calculate the current value according to Ohm's law;

S5. Change the positive and negative connection methods of the electrolytic capacitor, measure the current value or voltage value again and record the data;

S6. Check the results: Compare the changes in current values in steps S4 and S5 to determine the positive and negative connections of the capacitor test.

In the above solution, the principle of leakage current is used to detect whether the capacitor is connected forward or reversely. In the inventor's research, the electrolytic capacitor is a component that stores charges and is often used in circuits such as DC power filtering, coupling, and charge storage. The current can be measured by Use the size and direction to determine the positive and negative connections of the electrolytic capacitor. Normally, current should flow from the positive terminal of the power supply to the positive terminal of the capacitor, and then flow from the negative terminal of the capacitor back to the negative terminal of the power supply. Wrong positive and negative connection will cause the polarization effect inside the capacitor to be reversed, causing the capacitor to produce a large leakage current in the DC circuit. As shown in Figure 4, under ideal circumstances there will be no current between the two plates of the capacitor. However, since the dielectric between them is not completely insulated, a small amount of current will flow under the action of DC voltage, which is called leakage current. The leakage current detection method is based on this principle. Before the formal test, the leakage current at both ends of the electrolytic capacitor is measured to determine whether the positive and negative connections are correct.

In a preferred solution of the present invention, the test circuit in S1 includes a power supply, a resistor, a capacitor to be tested, and an ammeter or voltmeter.

In a preferred solution of the present invention, the power supply, resistor, capacitor to be tested and ammeter are connected in series in sequence.

In a preferred solution of the present invention, the power supply, resistor, and capacitor to be tested are connected in series in sequence, and the voltmeter is connected in parallel on both sides of the circuit.

In a preferred solution of the present invention, in S2, an ammeter installation method is used for capacitors with a capacitance less than 1 μF, and a voltmeter installation method is used for capacitors with a capacitance greater than 1 μF.

Compared with the prior art, the beneficial effects of the present invention are:

By using a test circuit to detect the leakage current of an electrolytic capacitor, you can determine whether the capacitor is connected correctly. Wrong connection will cause a significant increase in leakage current. Therefore, by detecting the leakage current value, you can effectively determine whether the sample is connected correctly. Correct. This method has the advantages of high detection and judgment accuracy and simple operation. It can avoid other problems caused by wrong connection of forward and reverse. For capacitors with different capacitances, an ammeter or voltmeter can be used for testing respectively, which has wide adaptability.

Description of the drawings

Figure 1 is a flow chart of a forward and reverse connection detection method for electrolytic capacitor testing based on leakage current detection;

Figure 2 is a test circuit diagram with an ammeter installed based on the forward and reverse connection detection method of electrolytic capacitor testing based on leakage current detection;

Figure 3 is a test circuit diagram of an installed voltmeter for a forward and reverse connection detection method of electrolytic capacitor testing based on leakage current detection;

Figure 4 is a schematic diagram of the leakage current principle.

Detailed ways

Please refer to Figures 1 to 3. In an embodiment of the present invention, a positive and reverse connection detection method for electrolytic capacitor testing based on leakage current detection includes the following steps:

S1. Establish a test circuit to test the circuit power supply, resistor, and capacitor to be tested. The power supply, resistor, and capacitor to be tested are connected in series in sequence;

S2. The test circuit installs a test ammeter or voltmeter according to the capacitance value of the capacitor. If the capacitance of the capacitor under test is less than 1μF, the ammeter is installed. An ammeter is connected in series between the power supply and the capacitor in the above circuit. For capacitances greater than The 1μF capacitor is installed with a voltmeter, and the voltmeter is connected in parallel on both sides of the resistor;

S3. Turn on the test circuit switch and read the current value record data on the ammeter;

S4. Turn on the test circuit switch, read the voltage value record data on the voltmeter, and calculate the current value according to Ohm's law;

S5. Change the positive and negative connection methods of the electrolytic capacitor, measure the current value or voltage value again and record the data;

S6. Check the results: Compare the changes in current values in steps S4 and S5 to determine the positive and negative connections of the capacitor test.

The test circuit with an ammeter installed is suitable for capacitors less than 1μF. Since low capacitance capacitors have low leakage current, the ammeter can accurately measure the current. If the leakage current is large, the ammeter will not be able to accurately measure due to the noise and instability of the charging capacitor. . Therefore, high-capacitance capacitors should be measured with a voltmeter. After the voltage value on both sides of the resistor is measured, the current value can be calculated through Ohm's law.

In this embodiment, by testing capacitors of different specifications, the positive and negative poles of the test capacitors have been clearly defined, and a test circuit with a parallel voltmeter is used for detection, and the following data are obtained:

Based on the data of the leakage current values of the above multiple groups of samples, it can be concluded that:

When the capacitor is connected positively, the current will drop to a value below tens of microamps within a certain period of time;

When the capacitor is reversely connected, the current will continue to be in a larger range of several hundred microamps or more.

Therefore, incorrect connection will lead to a significant increase in leakage current. This method can determine whether the forward and reverse connections of the capacitor are correct. The judgment accuracy is high and the operation is simple. It can effectively avoid test results caused by incorrect connections. .

Although the embodiments of the present invention have been shown and described, those of ordinary skill in the art will understand that various changes, modifications, and substitutions can be made to these embodiments without departing from the principles and spirit of the invention. and modifications, the scope of the invention is defined by the appended claims and their equivalents.

Claims (5)

1. A positive and reverse connection detection method for electrolytic capacitor testing based on leakage current detection, which is characterized by including the following steps: S1. Establish a test circuit; S2. In the test circuit, install a test ammeter or voltmeter according to the capacitance value of the capacitor; S3. Turn on the test circuit switch and read the current value record data on the ammeter; S4. Turn on the test circuit switch, read the voltage value record data on the voltmeter, and calculate the current value according to Ohm's law; S5. Change the positive and negative connection methods of the electrolytic capacitor, measure the current value or voltage value again and record the data; S6. Check the results: Compare the changes in current values in steps S4 and S5 to determine the positive and negative connections of the capacitor test. 2. A positive and reverse connection detection method for electrolytic capacitor testing based on leakage current detection according to claim 1, characterized in that the test circuit in S1 includes a power supply, a resistor, a capacitor to be tested and an ammeter or voltmeter. 3. A positive and reverse connection detection method for electrolytic capacitor testing based on leakage current detection according to claim 2, characterized in that the power supply, resistor, capacitor to be tested and ammeter are connected in series in sequence. 4. A method for positive and negative connection detection of electrolytic capacitor testing based on leakage current detection according to claim 2, characterized in that the power supply, resistor, and capacitor to be tested are connected in series in sequence, and a voltmeter is connected in parallel on both sides of the circuit. side. 5. A method for positive and negative connection detection of electrolytic capacitors based on leakage current detection according to claim 1, characterized in that in the S2, an ammeter installation method is used for capacitors with a capacitance less than 1 μF, and an ammeter installation method is used for capacitors with a capacitance greater than 1 μF. The capacitor is installed using a voltmeter.