The problem of electrolytic capacitor selection is solved at once

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The problem of electrolytic capacitor selection is solved at once [Copy link]

The problem of screening electrolytic capacitors. The
electrolytic capacitor is an important component of electronic ballasts and switching power supply products. Its quality problem directly affects the quality of the whole machine. How do you screen and inspect them in your respective companies? I hope to communicate here so that we can jointly improve our respective technical levels and the product quality of the entire industry, and enhance the competitiveness of Chinese products in foreign markets.

Screening Methods for Electrolytic Capacitors

Electrolytic capacitors are a kind of component that is difficult to control the quality of in the electronics industry. There are many product quality problems caused by electrolytic capacitors. Many manufacturers do not know how to check the quality of electrolytic capacitors and have to spend a high price to buy brand-name electrolytic capacitors, which will increase costs a lot. After exploration and practice, I have summarized a set of efficient unconventional screening methods and self-made fixtures to introduce to everyone. Whether it is a famous brand, a miscellaneous brand or a fake brand, you can tell the quality of the product by just trying it. Conventional testing methods are generally available in e-books, so this article will not repeat them. In addition, I am proud that my former electrolytic capacitor supplier also asked me to make several sets for comparing the quality of its own products with those of competitors.

Principle: The main problem with the electrolytic capacitors used in electronic ballasts is that the withstand voltage is not enough or the temperature coefficient is poor during operation, causing damage to the electrolytic capacitors. This method is to detect the quality of the electrolytic capacitors by charging and discharging under the condition of the extreme working withstand voltage of the electrolytic capacitors. If conditions permit, it is better to screen at high temperatures. If the performance of the electrolytic capacitor is not good enough and there is a slight leakage, the charge stored in other electrolytic capacitors will be released through this capacitor, resulting in the capacitors with poor performance being blown up. Electrolytic capacitors with good performance are intact. The circuit diagram is as follows:

Selection of main components: T1 uses a 0-250V/1KW auto-coupled voltage regulator, T2 needs to be customized, the parameters are 500W , 220/380V step-up isolation transformer. The DC voltmeter uses a 1000V range. S1 and S2 use a linked switch, and it is best to use the emergency brake switch on the machine tool instead. The bulb can be an ordinary Angelica bulb. The fuse can be a delayed fuse on a color TV.

Production method: First make a fixture that can fix the pins of many electrolytic capacitors to be tested and can reliably connect them electrically . Then use a box and install everything inside the box. The voltmeter, light bulb, switch and voltage regulating handle are installed on the outer surface of the box. After connecting the electrical circuit, you can start screening electrolytic capacitors.

Instrument debugging method: first adjust the working voltage according to the requirements of the electrolytic capacitor, install the electrolytic capacitor on the fixture, clamp it, close the box cover, and press the power switch. At this time, the light bulb lights up and the pointer of the voltmeter rises, indicating that the circuit is charging the electrolytic capacitor. When the specified voltage is reached, the light bulb goes out. Rotate the switch again to make the switch jump. At this time, the light bulb lights up, indicating that the electrolytic capacitor is discharging, and the pointer of the voltmeter drops. This indicates that the instrument is working normally.

Selection method of rated working voltage: Generally, the rated working voltage is 110-120% of the marked voltage of the electrolytic capacitor . If the marked voltage is 400V , then the working voltage is between 440-480V . If the instrument is used at high temperature, select 440V , and if it is used at low temperature, select 480V .

Screening operation method: first adjust the working voltage according to the mark of the electrolytic capacitor, turn off the power switch, install the electrolytic capacitor, clamp it, and cover the box cover. Turn on the power switch, turn it off, repeat three times, then turn on the power switch, keep it for half an hour, and turn it on and off three times again, and finally turn off the power switch and take out the electrolytic capacitor. This step of screening is completed.

Note: If any electrolytic capacitor explodes, cracks, or leaks during the test, it is considered unqualified. The others can be used as qualified products.

A comprehensive screening method also includes testing of capacitance, leakage current and loss angle.

PMU2007

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bxjiawei

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