What is the close relationship between leakage current and voltage in electroly...
What is the close relationship between leakage current and voltage in electrolytic capacitors
? The withstand voltage of a capacitor means the voltage that the capacitor can withstand under certain conditions for continuous use. If the working voltage applied to the capacitor exceeds the rated voltage, the insulating medium inside the capacitor may be broken down, causing a short circuit between the pole pieces or serious leakage. Therefore, the operating voltage of the capacitor cannot be greater than its rated withstand voltage to ensure the reliable operation of the circuit.
For electrolytic capacitors, leakage current is an important item in performance indicators. The leakage current of the electrolytic capacitor is closely related to the voltage, and the leakage current increases with the increase of the working voltage. When the working voltage is close to the forming voltage of the anode, the leakage current will rise sharply. By testing the leakage current of the electrolytic capacitor, its ultimate withstand voltage and rated withstand voltage can be calculated, which has direct reference significance for the value of the capacitor withstand voltage in the circuit.
Based on this principle, the author designed and produced a capacitor withstand voltage tester, which has simple circuit, low cost and easy production, which better solves the problem of capacitor withstand voltage test under amateur conditions.
The transformers T1 and T2 are of the same model, but are connected back to back to provide two sets of high and low voltage power supplies, and play a role in isolation. After the low voltage is rectified and filtered, R1, DW1, Q1, Ral~Ral 1 form a constant current source with adjustable current. After being rectified and filtered, the high voltage is divided by Rbl～RblO and DW2, and Q2 outputs an adjustable DC voltage.
When using, select the appropriate voltage Uc and current Jc, and connect the measured capacitor to the two points Cxa and Cxb. At this time, you will see the voltmeter pointer deflection slowly, and it will stop after reaching a certain position. The voltage pointed by the pointer is this The withstand voltage of the capacitor when the leakage current is lc.
Band switches K3 and K4 (11 positions for each single gear) are respectively the test voltage and current (ie leakage current) selection switches, and their test ranges. List of components in the test circuit.