GE Grid Solutions DC Capacitors Product Selection & Application Guide Capacitors for High Current, Power Semiconductor and DC Applications

Product Selection & Application Guide

Capacitors for power electronics require special high performance designs for varied applications. This catalog describes capacitors for a number of demanding applications where high currents and/ or high voltages are common. Given the special nature of these types of applications, care must be taken to ensure that the capacitors are correctly applied. Information is included to help with the more common application conditions. An application data sheet is also provided to enlist the help of GE’s Application Engineers. Please use this sheet if you need assistance or want to verify your own calculations.

Descriptive Information

Film Foil Electrode Construction

GE’s Foil Electrode capacitors are manufactured with sheets of high quality aluminum foil as the electrodes. The dielectric consists of two sheets of polypropylene film. The film is manufactured in GE’s own Capacitor Materials Operation. It is specially designed with a rough surface to allow impregnation by the dielectric fluid. The aluminum foil electrodes extend, one on each end of the capacitor roll, so that a solder connection can be made. Depending on the typical current for the type of capacitor, the internal connections from the roll ends to the terminals are either braided cables or tin-plated copper straps. This construction provides capacitors that are inherently capable of handling high RMS and peak currents.

DIELECTRIC FLUIDS GE’s dielectric fluids are chosen for specific characteristics that match the other components in the capacitor dielectric system and the applications for which the capacitors are intended. Each fluid is based on one or two major constituents and blended with proprietary additives for optimum performance. 

 DIELEKTROL VII A Benzyl Toluene-based fluid used for film/foil high current products.

SCR Commutation Capacitors

A97F8600 / A97F8700 Series 600 to 1500 Volts Peak
This family of capacitors is designed for high-current applications, such as (1) SCR commutation, (2) snubbers for SCRs, GTOs and other power semiconductors, and (3) for any other circuits where the combination of frequency and voltage results in high RMS currents. An Application Note is provided to assist in the proper use of these devices. It is strongly recommended that users refer to GE engineers for assistance if there are any questions as to the correct selection of capacitors. The A97F8600/A97F8700 Series have an all-film dielectric and, due to the much lower dissipation factor, can handle much higher currents than the older film paper designs. Advances in capacitor Dielectric technology have made paint unnecessary, in most cases. This along with GE’s commitment to environmental programs has led to the elimination of painted cases in this product line. Removal of the paint has minimal affect on the RMS current ratings; see the standard ratings charts for proper application.

SCR Commutation Capacitors

97F7500 Series SCR Commutation Capacitors   250 Volts Peak

The 97F7500 Series is a special purpose line designed for applications where a large micro-farad value at low voltage is required in a small size. The dielectric system is self clearing metallized polypropylene. Typical applications are in SCR chopper circuits and low-voltage ac filters. Refer to Application Note on page 12 for assistance in the correct application of these capacitors. Please note that previous offering of these capacitors was with painted cases, to improve heat dissipation. The units will no longer be painted as part of GE’s commitment to environmental programs. Please note the change in RMS current ratings from previous catalogs.

Snubber Capacitors

A28F5000S Series Snubber Capacitors   1000 and 2000 Volts Peak/Max DC

The A28F5000S series of Snubber Capacitors are designed for use in power semiconductor circuits to protect the semiconductor by limiting the rate of voltage rise. The dielectric system is polypropylene with foil electrodes. The RMS currents encountered in these circuits are usually low; however, the peak currents are very high. Refer to the Application Data correct application of these capacitors.

General Purpose DC Capacitors

General Purpose DC Capacitors   1500 and 2500 Volts Peak

This line of General Purpose DC Capacitors is made with film dielectric technology for 1500V and 2500V ratings. These capacitors are typically used in DC filters at voltages above those served by electrolytic type construction.