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Aluminum Electrolytic Capacitor The Higher The Withstand Voltage, The Higher The Ambient Temperature
- Jun 06, 2017 -

Aluminum Electrolytic Capacitor  are electronic devices on the circuit board is a very common passive electronic components, mainly in the electronic circuit for energy storage filter to smooth the voltage. In most cases Aluminum Electrolytic Capacitor  have polarity, can not be used anti. But whether or not it is a polar aluminum electrolytic capacitor, can not be used in the AC voltage circuit.

Aluminum electrolytic capacitor after the first charge, after discharge and short-circuit the two ends of the capacitor (to confirm the voltage at both ends of 0V), remove the short circuit, the aluminum electrolytic capacitor voltage will gradually rise at both ends and reach a certain value of the voltage, this phenomenon Called the voltage regeneration phenomenon, the corresponding voltage value for the regeneration voltage (or recovery voltage), some literature also known as the residual voltage (residual voltage), or called the redundant voltage. Personally feel that the regenerative voltage is more appropriate than the residual voltage or the redundant voltage, because from the outside, Aluminum Electrolytic Capacitor  have been completely discharged, the voltage is 0V, there is no remnants, if not put 0V called on the reasonable point; I have extra meaning, from a certain point of view than the remnants of a more reasonable point. Through the experiment found that aluminum electrolytic capacitor charge needs to be sufficient, that is, to have a certain time, and a charge and discharge process, in order to exist regenerative voltage phenomenon, if it is in a very short period of time to charge the capacitor to a certain voltage immediately after discharge and do Short circuit action, generally do not appear regenerative voltage phenomenon.

The size of the regenerative voltage and the capacity of the aluminum electrolytic capacitor, the withstand voltage, the thickness of the aluminum foil, the manufacturing process, the standing time and the standing ambient temperature. The larger the capacity, the thicker the foil, the higher the pressure, the higher the ambient temperature, the higher the regenerative voltage will be. According to the relevant information recorded in the 25 ℃ temperature environment, the regeneration voltage in the standing time 100S ~ 1000S will reach the discharge before the voltage (non-capacitance standard voltage) of 10%, the maximum may reach 40 ~ 50V. The regenerative voltage increases with the lengthening of the standing time, reaches the peak at 10 to 20 days, and then decreases gradually. I actually experiment test found that in the standing 4 to 9 days the regeneration voltage will reach the highest point, if the capacitor is not placed on the circuit board, because there is no discharge circuit loss, and then increase the voltage will remain for a long time. Manufacturers to help do the experimental data, the eighth day to reach the highest, then basically remain unchanged, to 27 days or so almost no change. But if it is installed on the circuit board, due to the existence of the relevant circuit of the discharge effect, the voltage reaches the peak will slowly discharge and reduce, and there are some small fluctuations. Aluminum Electrolytic Capacitor  in the actual board test data (the highest voltage of the day). Another experiment found that after a night, the regeneration voltage will be reduced, the next day and gradually increased. That is, every morning test the voltage will be higher than the previous afternoon, the voltage is much higher, and then gradually increased to 14:00 to 17:00 between the day will reach the highest voltage, should be the main reason for the change in ambient temperature.

What is the energy of this regenerative voltage? I designed an experiment, that is, through the Aluminum Electrolytic Capacitor  connected to both ends of a small resistance to discharge, and then measure the voltage across the two resistors, according to the voltage to calculate its energy. Is the waveform when the regenerative voltage is 7.6V. After calculation, the energy generated on the resistor is about 1.86mJ; the waveform when the regenerative voltage is 14V is calculated, and the energy generated on the resistor is about 7.14mJ. So as long as the discharge is complete, even if the regeneration voltage is relatively high, but its energy is limited.

Although the regenerative voltage is limited, the regenerative voltage may be relatively high. If the production process is not prevented and handled, it may cause damage to some low-voltage drive components (such as CPU / memory and other integrated modules), and even direct breakdown failure ; On the RC timing circuit trigger system and phase mobile network caused by malfunction; Aluminum Electrolytic Capacitor  connected to the circuit, the moment may produce spark anomalies, some sensitive people may be frightened and other heart effects; if the staff direct contact, some people There may be a slight electric shock.

Therefore, for the use of Aluminum Electrolytic Capacitor  need to pay attention to the regeneration of the voltage problem, especially high-voltage large-capacity capacitors. As the aluminum electrolytic capacitor manufacturers in the production process need to do the aging of the charging action, so the factory after the existence of voltage regeneration problem, so the packaging, the general terminal will be covered with a layer of aluminum foil or conductive silicone to Aluminum Electrolytic Capacitor  at both ends Has been in a short-circuit discharge state, that is, short-circuit state packaging method. And found in the use of regenerative voltage, it is recommended to discharge and then use. Discharge is generally not a direct short-circuit discharge, because the instantaneous short-circuit discharge may cause damage to the capacitor itself, it is recommended to use a discharge resistor for discharge, the resistance between 100Ω ~ 1KΩ is appropriate. In the electronic circuit design, high-voltage large-capacity Aluminum Electrolytic Capacitor  should be designed in parallel discharge resistance, in order to avoid the generation of renewable voltage and hazards. Electric power capacitors on the early switching power supply are designed to bleed the resistor, and later because of standby power requirements more stringent and other reasons were canceled, so the production line on the switching power supply pre-commissioning or functional test after the need for the relevant electrolytic capacitors Discharge action is very necessary, otherwise there will be trouble.