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The novice can solve the frequency converter common fault diagnosis and processing.(4)
- May 08, 2018 -

1.3 the filter electrolytic capacitor is damaged.

1.3.1 judgment

Appearance burst, aluminum shell bulge, plastic outer casing crack, out of the electrolyte, the relief valve open or crushed out, small capacitor top part of the disc cracking, terminal badly corroded, cover plate deformation, fall off, electrolytic capacitor has been damaged.Using multimeter to measure open circuit or short circuit, the capacity is obviously reduced, and the leakage is serious (the resistance is smaller after the final stability is measured by multimeter).

1.3.2 find out the cause of capacitor damage.

(1) the quality of the device itself is not good (large leakage current, large loss, insufficient pressure, chlorine ion and other impurities, poor structure, short life).

(2) the rectifier bridge before filtering is damaged, and the ac power is directly entered into the capacitor.

(3) the partial pressure resistance is damaged, and the partial pressure difference causes the first breakdown of a capacitor, then the relevant other capacitors are also punctured.

(4) the capacitor is not installed properly, such as insulation damage, the shell is connected to the undesired potential, the electrical connection and welding are not good, resulting in bad contact and heating and damage.

(5) the heat dissipation environment is not good, which makes the capacitor temperature rise too high, which is damaged by the long time.

1.3.3 replacement of capacitance.

(1) change the filter capacitors had better choose the same as the original model, in the moment can't get the same model, must pay attention to the following: high voltage, leakage current, capacity and overall dimensions, polarity, the installation should be the same, and choose to withstand large ripple current, long life.

(2) the change in the process of dismantling note electrical connections (screw connection and welding) is firm and reliable, positive and negative can not wrong, fixed with a band to be firmly fixed, and shall not damage the capacitor insulation sheath, bleeder resistor connected as is, and to measure the resistance value, should make partial pressure evenly.

(3) has placed more than a year of electrolytic capacitor, should measure the leakage current value, shall not be too big, put forward first and direct current aging, direct current (dc) and lower first, reduced when the leakage current, voltage rising again, and finally in the rated voltage, the leakage current value shall not exceed the standard value.

(4) because of the size of the capacitor is not appropriate, repair and replacement of the capacitor can only in other position, must pay attention to from the inverter module to the capacitance bus cannot be longer than the original bus, surrounded by two +, - busbar area must be small as far as possible, had better use twisted-pair cable.This is because the capacitor connection bus extension or +, - bus bar surrounded area of the bus bar inductance increases, cause pulse surge up on the power module, damage power module or overvoltage damage absorption device.In case of necessity, and the other to absorb the high frequency high voltage surge capacitor with short line add to the inverter module, help absorb bus over-voltage, make up for the harm done by the capacitor connected bus extension.