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| Treatment of filter electrolytic capacitor damage in inverter maintenance experience |
| Date of issue：2015-01-05 15:50:07 see： |
| Filter electrolytic capacitor is also one of the components that are often damaged in frequency converter. Here for you to say, how to judge the filter electrolytic capacitor damage and replacement method. 1、 Damage judgment method of filter electrolytic capacitor 1. Observation Check whether there are cracks, explosions, bulging of aluminum shell, electrolyte outflow, safety valve opening or being pressed out, split crack at the top, serious corrosion of terminal, deformation and falling off of cover plate. 2. Use a multimeter to measure the open circuit or short circuit, whether there is obvious reduction of capacity and serious leakage (refers to whether the resistance value after final stability is small). 2、 Causes of electrolytic capacitor damage 1. Quality issues 2. The rectifier bridge is damaged, resulting in direct AC current entering the capacitor. 3. The breakdown of a capacitor is caused by the damage of the divider resistance and the uneven voltage distribution, followed by chain breakdown. 4. Poor installation, such as insulation damage, shell connected to the potential should not be, poor electrical connection and welding, resulting in poor contact and heat damage. 5. Poor cooling environment 3、 Replace electrolytic capacitor 1. Alternative electrolytic capacitor selection. It is better to use the same model. If not, the voltage withstand, leakage current, capacity, overall dimension, polarity and installation method should be the same when choosing the substitute, and the variety that can withstand large ripple current and long life should be selected. 2. The electrical connection shall be firm and reliable, and the positive and negative electrodes shall not be wrongly connected. The clamp for fixing shall be able to fix firmly and shall not damage the outer insulation cover of capacitor. The partial voltage resistance shall be connected as it is, and the resistance value shall be measured to make the partial voltage uniform. 3. The leakage current value of electrolytic capacitor which has been placed for more than one year should be measured, and the leakage current should not be too large. Before installation, add DC aging first, and then increase the voltage when the leakage current decreases. Finally, when the leakage current is at the rated voltage, the leakage current value shall not exceed the standard value. 4. Because the size of the capacitor is not suitable, and the repaired and replaced capacitor can only be installed in other positions, it must be noted that the bus from the inverter module to the capacitor cannot be longer than the original bus, and the area surrounded by two + and - buses must be as small as possible, and the twisted pair method is preferred. This is because the extension of the capacitor connection bus or the enclosed area of the + and - bus will increase the bus inductance and cause the rise of impulse Overvoltage on the power module, resulting in damage to the power module or overvoltage absorption device. In case of no alternative, the high-frequency and high-voltage surge absorption capacitor is added to the inverter module with short wires to help absorb the over-voltage of the bus and make up for the harm caused by the extension of the capacitor bus. |
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