Power

5,000-hour, 105° C electrolytic capacitors offer stable characteristics for full life

28 October 2020

Figure 1: 381LL long-life electrolytics. Source: Cornell DubilierFigure 1: 381LL long-life electrolytics. Source: Cornell Dubilier381LL long-life electrolytics from Cornell Dubilier attack a common design problem encountered when applying aluminum electrolytic capacitors. Cylindrical electrolytics, such as snap mounts and axial-leaded types, lose capacity over their normal lifespan as a result of electrolytic dry-out. A frequently applied solution to this problem is to over-spec the capacitance value, in order to overcome the anticipated lifetime loss and increase in equivalent series resistance (ESR). The new 381LL eliminates the need to over-specify capacitance value, as it provides stable capacitance, ESR and DF over its 5,000-hour operational life.

Capacitance values range from 740 µF to 150,000 µF. Working voltages range from 16 to 250 W V DC. ESR is as low as 0.012 W for 100,000 at 16 V DC/125 Hz. Operating life is 5,000 hours at 105° C, with no derating. As a result, it is estimated that over its lifespan, the 381LL will provide 25% more ripple current than most competitive types.

The performance enhancements provided by the 381LL are the result of a new advanced electrolyte system and the industry’s most stringent test production procedures. As a result, the need to spend more on larger capacity devices has been eliminated. This may also provide a physical size savings.

The 381LL is rated at 10 g for vibration stress, with 10 to 55 Hz applied vibration; two hours on each plane. The full temperature range for operation or storage is -55° C to 105° C.

General applications include any circuit requiring low ESR, high ripple current and long life. This includes holdup, bulk storage, power filtering and DC link circuits. The 381LL is also particularly well-suited for use as motor-drive bus capacitors.

Cornell Dubilier’s 381LL, long-life aluminum electrolytic capacitors are available from Digi-Key, Mouser, TTI and other distributors. For more information on this series visit Cornell Dubilier.

Metalized polypropylene film capacitor modules

Figure 1: 381LL long-life electrolytics. Source: Cornell DubilierFigure 1: 381LL long-life electrolytics. Source: Cornell Dubilier

Cornell Dubilier has also announced a new series of DC link polypropylene film capacitor modules, aimed at high-power inverters. The MDL series offers capacitance values ranging from 100 µF to 1,000 µF, with applied voltages of 900 V DC to 1,300 V DC.

Designed as an alternative for multiple cylindrical bus-mounted capacitors, banked in parallel, these modules have higher energy density and simplify bus connections by reducing the number of terminations. By using a single DC link capacitor in a compact package, smaller inverter topologies, lower costs and enhanced system reliability can be achieved. The MDL series also features extraordinarily long life, meeting a 5,000-hour life test at rated voltage, with a core temperature of 85° C. This translates to an expected life expectancy of 200,000 hours at 60° C without voltage derating.

A key feature of the MDL series is that it provides large bulk capacitance with high ripple current capability. Ratings for some values exceed 500 Arms at a core temperature of 55° C. Combined with their rugged aluminum prismatic cases, the modules are well suited for the types of high-power inverters used in wind, solar and fuel cell systems. Other applications include UPS, switching power supplies and large motor drives.

The series consists of 12 values, with physical sizes varying from 76 x 203 x 163 mm to 101 x 367 x 163 mm, depending on capacitance and voltage. Technology-wise, the internal construction is based on Cornell Dubilier’s well proven DC link film technology. Each capacitor element utilizes low-loss, high-grade polypropylene dielectrics. The internal bus structure exhibits low inductance; and connections to the capacitor elements are made with advanced welding techniques for highest reliability. Each unit passes through Cornell Dubilier’s industry-leading 100% burn-in testing. The series is RoHS-compliant and meets IEC 61071 and UL94V-0.

Cornell Dubilier MDL series modules are available by special order. Visit Cornell Dubilier to learn more.



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