Recently, Sprague Electric has been developing a new energy discharge capacitor family type for intermittent duty, the 682P. This energy discharge capacitor takes advantage of the high dielectric constant of polyvinylidence difluroide and the silicone oil impregnated soggy-foil design to produce an extremely high energy density capacitor, which is finding application in portable laser range finders, portable medical equipment and as an energy source in ballistic missiles. Table IV provides a size comparison of 54.0?F energy discharge capacitor rated at 4000VDC of the 382P and 682P constructions. A more graphic comparison of the dramatic size reduction realized by the 682P design is provided in Photograph 4.

While the ultimate peak current, duty cycle and life of this capacitor design has yet to be determined, some data is available for review. One group of capacitors has been tested for 5000 charge/discharge cycles at 25 degrees C with 4000 VDC applied. The peak discharge current was 60 amperes at a duty cycle of one pulse per second for six seconds followed by a fifteen minute rest period. Table V provides the mean capacitance, dissipation factor and insulation resistance initially and at the completion of 5,000 cycles. Graph 5 provides the RC product initially and as the test progresses.

Communication = Success

When describing the application and specifying the design criteria for energy discharge capacitors, the user should have some important parameters established. They are:

1. Operating duty Cycle and Rep Rate.
   The maximum repetition rate should be specified, and whether the capacitor will be used intermittently or continuously.
2. Operating Temperature Range.
   Since degradation due to thermal aging is one of the major causes of capacitor dielectric deterioration, the temperature for both non-operating and operating conditions should be specified. It is simplest to specify the minimum and maximum case temperatures at which the capacitor shall operate, since the user may be employing heat sinks, forced air cooling, or liquid transfermedia, etc.

3. Voltage and Current Requirements.
   These parameters let the designer select, based on knowledge and experience, the dielectric system and end connection type best suited for the application.
4. Life Expectancy
   How many charge/discharge cycles are required?
5. Mechanical Requirements.
   The vibration and shock requirements should be specified, since severe stresses may require special internal construction. The size and mounting requirements should be specified with the necessary dimensions and tolerances. Marketing requirements are important as well.
6. Environmental Conditions.
   The environment the device will be subjected to is critical in design work. Is heremeticity required? Will the device be subjected to any corrosive conditions?

When the user has a general understanding of the capabilities and limitations of the energy discharge capacitor (hopefully supplied by these discussions), and clearly describes the application, he and the capacitor Design Engineer can work more effectively together toward the optimum design and use of these special capacitors types.

Acknowledgements
The author wishes to express his appreciation to Mr. Leonard Adelson, Mr. Charles Heinrich, Mr. Daniel Mannheim and Mrs. Donna Meister. Mr. Mannheim performed the initial feasibility studies of the 682P design. Iw ould like to thank Mr. Leonard Adelson for many valuable consultations during the preparation of this paper. The extensive manufacturing and testing experience of Mr. Heinrich were invaluable. Mrs. Meister, with her artistic abilities, is responsible for the diagrams.

References

1. Edgerton, Harold e., Electronic Flash, Strobe, McGraw-Hill, 1970
2. Final Report, N. Agostinelli, United States Army Electronic Command, Fort Monmouth, New Jersey, July 1970.
3. Rondeau Ernest B., Metallized Energy Storage Capacitors, October 1962.
4. Sprague Electric Engineering bulletins Numbers 2148B, 2152, and 2151B.

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