Pulse handling capability of energy storage metallized film capacitors

The aim of this work was to point out the current performance of metallized polypropylene film capacitors. Many tests have demonstrated that the contact between the sprayed terminations and the metallized electrodes is one of the most critical points for capacitors manufactured with this technology, generally when the capacitors are used in impulsive conditions. This is the case of energy storage application. The effects of pulses having high peak current, but short duration (20-40 μs), are compared to the effects of pulses having lower peak current, but higher duration (200-300 μs). The comparison is made between pulses having the same I²·t. The modalities of manufacture and the conditions during metallization, winding, and spraying processes are examined in the context of certain mechanical problems during the pulse transient, with particular attention to the connections on the sprayed terminations. The possibility to detect the beginning of detachment of sprayed ends by the use of photodiodes has been taken into consideration. The result of these studies has been an improvement in the performance of energy storage capacitors meeting the discharge and life requirements of the National Ignition Facility (NIF), Lawrence Livermore Laboratory, class capacitors