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Film capacitance current impact test
Jan 10, 2019

Power electronic capacitors are usually used in non-power frequency applications, and their peak current and shock current resistance are the key technical parameters. Since the current resistance is the weakest link of the metallized film capacitors, the products with this index must be tested for their current resistance. A high-power electronic switch is used to form a capacitor charging and discharging circuit, and the discharge current, current attenuation cycle and current and voltage change rate are controlled quantitatively by adjusting charging voltage or discharge circuit parameters.

1. Set the charging voltage value U, which determines the peak discharge current, I=U/R.
2. Set the charging time according to the capacitor capacity C, the internal resistance r of the charging power supply and the required voltage U to determine the charging time.
3. The charging switch s is controlled by an adjustable time relay, s is closed, and the adjustable dc power supply E is used to charge the test capacitor c.
4. When the charging time is up, S turns on and the charging ends, the control circuit sends a pulse to SCR, SCR conducts, and capacitor C starts discharging.
5. Due to the existence of resistance and inductance in the discharge circuit, the discharge process is oscillating attenuation, which ends after being oscillated for several weeks. The SCR is closed with zero current, and the cycle time from the beginning to the end of oscillation is generally much less than 1 s.
6. After the discharge, the charging switch closes and starts charging again. Repeat the above test.

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