Links to the Plug-In applet:

Your browser has JavaScript turned off!


You need to enable JavaScript to use the applet.
Open your browser preferences, enable JavaScript,
and then click "Reload" or "Refresh."

            New features!

            Overview

            How the applet works

            About Java applets and JavaScript

            Browser requirements

            Using the applet effectively

            Limitations and Cautionary Notes

            Legal Disclaimer



 

New Features!

Cornell Dubilier now offers Spice models of many of its wet aluminum electrolytic capacitors. We have a new online impedance modeling applet that allows the user to select any standard catalog part number among 16 types. The capacitance, ESR, and impedance are then graphed versus frequency at several temperatures. A Spice simulation program listing is available with a mere click of a button, and this model is readily cut and pasted into a Spice simulator. This is a new offering from Cornell Dubilier, and we will be refining the models and adding new types over the coming months.

The latest version of Java offers new capabilities. New Java version 1.4 replaces the old Java 1.1 to offer a user interface that's easier to use. Tool Tips explain the purpose of each button or field in the applets as they are pointed to with the mouse. Once the user gains familiarity, this feature may be turned off by unchecking the Tool Tips checkbox in the applets. Message boxes are more informative and easier to read and to close.

Plug-in Types 4CMC, 400C, 420C, 450C, and 401C offer extended capabilities. For the ultimate robust package in medium-size aluminum electrolytic capacitors, check out our plug-in capacitor ratings. These capacitors have been completely re-designed with the industry's best anode foil and extended cathode construction for superior thermal resistance. Offering up to 50% more capacitance than a comparable screw-terminal capacitor, these caps boast low ESR, high ripple, and long life. Mechanically robust, ultra-pure headers have three heavy-gauge pins (positive, negative, and dummy) to prevent incorrect polarity insertion and to provide mechanical stability during vibration. If you are already familiar with our screw-terminal capacitor families, you will feel right at home with the part-numbering system for our plug-in capacitors. Just replace the first letter of a screw-terminal type with a "4" and Presto! that's the corresponding plug-in type. Therefore, the 4CMC is the base plug-in which corresponds to the DCMC, and higher performance is achieved with the 400C (related to the 500C), the 420C is even heavier-duty, and the 450C is the ultimate medium-size high-performance 'lytic on the market. The 401C also has high performance, but is limited to 250 VDC due to its special -55 ºC rated electrolyte.


New sizes and voltages extend our screw-terminal line-up. We now offer 550V rated capacitors (600V surge) in types DCMC and 500C. We also now offer 500V/105 ºC rated type 550C. In addition, we have added a new length, 7.625", to all of our 3" and 3.5" diameter screw-terminal capacitors. This length is the most ecomonical for many high-volume applications for large screw-terminal capacitors.

A wide range of competitive Snapmounts. 380LQ, 381LQ and 380LR offer high value! The LQ series offer 10-20% higher volumetric capacitance density, and the 381LR type offers extremely high ripple capability. The L series are still supported but due to their lower capacitance, are not recommended for new designs.

There is a feature in the double applets that allows you to copy the information from the left pane to the right or vice-versa; just click the arrow button corresponding to the desired copy direction.

The java snapmount applet looks up the latest catalog capacitances, case sizes, and typical ESR's automatically with the applet's automatic database search feature for the current catalog types. Just choose the type, rated voltage, capacitance, case size, and part number in sequence as prompted. Or first choose the competitor's type, and the applet will find the CDE equivalent type.

The database search occurs across the internet automatically in the background. When a new capacitor type is accessed, there will be a delay of 2 to 20 seconds during which time the database for that type is downloaded into your browser. After that time, the information is readily available.

You can type over and replace the calculated ESR at either or both frequencies at the calculated core temperature. This feature can enhance the applet's accuracy if you have measured the actual ESR of our capacitor at the temperature and frequency. The applet displays its automatically-calculated ESR's so you can see the effects of frequency and temperature.



Overview:

This is a Java applet that calculates temperature rise above ambient from the capacitor's thermal resistances and the ripple-current power. Then it calculates the expected operating life for the core temperature, adjusted for ESR increase over life.


How the applet works

The applet calculates core temperature based on CDE's 7-R Thermal Model. This is a lumped-parameter model based on extensive thermal tests and finite element analysis thermal models. First, the applet calculates axial and radial thermal resistances from the core of the capacitor element using the capacitor element size, can size and type of construction. It also calculates the thermal resistance from the can wall and bottom to the ambient air and to an attached heatsink, if any. It expresses the thermal loop equations in terms of these resistances, the generated power, and the air and heat sink temperatures to obtain the core temperature.

To calculate ripple power the applet first calculates the ESRs at Frequency 1 and Frequency 2 at room temperature. Then it calculates the power and ESRs at average core temperature as an iterative loop because the ESR depends on the core temperature, the core temperature depends on the power and the power depends on the ESR. The total power is the sum of the two ripple-current powers.

The core temperature is determined from the thermal loop equations and loop parameters. The applet calculates average core temperature over life by bumping the temperature rise up 20% to adjust for possible ESR increase during life. While room-temperature ESR can more than double during a capacitor's life, the hot ESR increases much more slowly and 20% is a reasonable approximation to the expected average increase in the hot ESR.

The applet calculates expected life as Lb x Mv x 2^((Tmax-Tcore)/10) where Lb is the base life, Tmax is the maximum permitted core temperature, Mv is a voltage-derating multiplier and Tcore is the average core temperature over life. See the Application Guide in our Aluminum Electrolytic Capacitors catalog and on our website for a full discussion of this approach.


About Java applets and JavaScript

Java was developed by Sun Microsystems to allow a single program to run cross-platform (e.g., on IBM-PC-compatible, MacIntoshes, under Unix and OS/2 and Windows NT and Windows 95, etc.) and is supported by Netscape, Internet Explorer, and other browsers. The implementation occurs through a Java Virtual Machine, which is native code local to your browser that recognizes the universal java bytecode of our applet. The applet itself is downloaded to your computer and the execution and modeling takes place locally on your computer. Java has tight security restrictions, and our applet cannot access your hard drive except in an extremely restricted way. Due to these built-in security restrictions, Java cannot even access your printer or printer functions.

Now even though the purpose of Java is to allow 'write once, run anywhere,' universal code, the appearance and behavior of Java applets vary from one machine/screen/OS/browser combination to another. These variations are generally in applet appearance (e.g., sizes of fonts and textboxes) and should not yield different life predictions. We have tested a small but varied subset of these combinations and are confident that this applet will be functional in almost all systems with Java capability. However, the font spacing and centering may not be perfect in your browser window.

JavaScript is completely different from Java, and is a C-like language that is incorporated directly into the web page HTML code. The JavaScript code is therefore completely public and cannot be held proprietary. In fact, most browsers will let you examine the web page code directly. Try 'View/Source' or similar command to examine the web page code, including JavaScript. Our applet pages use JavaScript to provide an applet-printer interface.


Hints:

Browser requirements

This applet requires a recent browser for full performance. We recommend Netscape 4.05 or later and Internet Explorer 4.0 or later.

You may get one or more of these error messages if your browser is not recent enough or is missing the necessary Java capability:

Correct the problem by installing a new browser.

As mentioned above, our applet web pages use JavaScript to provide the 'Printable Form' command button below the applet so that the applet results can be printed. This is necessary because Java cannot provide printer functionality directly. If your browser allows enabling and disabling of JavaScript, this setting must be enabled.


SPECIAL NOTES FOR AOL 5 AND AIM (AOL'S INSTANT MESSENGER): Most users of the AOL 5.x browser will have problems running the applet due to JavaScript incompatibilities. We suggest that you use Internet Explorer 4.0 (or later) or Netscape 4.05 (or later). Some users have had problems from AIM setting the Java VM (Virtual Machine) browser options to an incompatible state. If you have AIM or have used AIM in the past, and you receive a java-related error message when trying to open the applet with Internet Explorer, check your Java VM settings as follows. For IE4.x, select the View menu, and for IE5.x, select the Tools menu. Then select Internet Options / Advanced / Java VM. Make sure that the checkbox labeled "Java JIT Compiler enabled" is unchecked.

Using the applet effectively

The applet is useful not only in comparing different capacitor types such as the 381L vs 380L, but also in determining what ESR and life characteristics are needed. For example, if the typical ESR is 58 milliohms and the life of a 380EL in your conditions is too low, you may play what-if and lower the hot ESR's by up to 50% and advise us that you need the lower ESR. You can fax or e-mail (cde@cde.com) your design to us using copy/paste from the Printable Form. Be sure to include your name, company name, address, phone and fax number in your inquiry, along with your specific questions. We'll promptly propose a capacitor for your requirements.

Air is assumed to contact the entire can. Adjust air speed if a significant portion of the can is insulated.

Use 50 lfm for free convection cooling.

When using CDE snap-in capacitors in high ripple applications, some extra measures are necessary when the ripple is greater than 20 amps per lead set. Large solder pads and traces without thermal relief are recommended, along with at least 2 oz copper, sufficient to dissipate 1 watt of heat from each active lead while maintaining a lead temperature below 115 ºC or a rise of 30 ºC above ambient, whichever is less. For the 50 mm capacitors, both pairs of terminals should be connected to share the current equally.

Press the F11 key in Internet Explorer to toggle full-screen mode. It's more convenient.

Use the 'Printable Form' command button located just below the applet to create a text-only window from which the model results can be printed or cut/paste as text into another application.

Enter an rms current value for Ripple 1 that accounts for all low-frequency harmonics and enter an rms value for Ripple 2 that accounts for all high-frequency harmonics.

If the appearance of the applet becomes garbled during resizing, use the browser's Refresh or Reload command.

Note: The single applet displays one instance of the applet in the browser window and is better for small or low-resolution monitors, while the double applet displays two instances of the applet for side-by-side comparison of results from different capacitor and thermal scenarios. The load time of the double applet is no longer than for the single applet. However, the database information for each capacitor type is downloaded separately for each applet instance.

This applet is only valid for Cornell Dubilier capacitors, as our construction and characteristics are unique.

Bookmark this page and return as often as you like for your capacitor life calculations. We'll be adding features and refinements throughout the coming months.

Special Notes for the Screw-Terminal Capacitor Applet

For assistance in filling out the 'Full Can Capacitance' and 'ESR' fields, you can use our latest catalog ratings, as they are full-can ratings. You can look up these ratings using the applet's new 'Search Catalog' button for our current capacitor types (types ending in 'C'). This feature will populate the 'Capacitance' and 'Full Capacitance' fields with the nominal capacitance, and the 'ESR' field with 70% of the ESR limit, which is generally close to a capacitor's typical initial ESR.

The applet is useful not only in comparing different capacitor types such as the DCMC vs 520C, but also in determining what ESR and life characteristics are needed. For example, if the catalog ESR is 18 milliohms and the life of a DCMC in your conditions is too low, you may play what-if and lower the ESR by up to 50% and advise us that you need the lower ESR. You can fax or e-mail (cde@cde.com) your design to us using copy/paste from the Printable Form. Be sure to include your name, company name, address, phone and fax number in your inquiry, along with your specific questions. We'll promptly propose a capacitor for your requirements.

We recommend types ending in 'C' for new design. In order of increasing life and ripple capability, these types are DCMC, 500C, 101C, 520C, and 550C. These types incorporate our Thermal-Pak construction and run much cooler in high ripple current applications, especially when attached to a heatsink. We included other types to help you with existing designs.

'Heatsink Characteristics' in the applet means: 1. If 'C' is checked: Infinite heatsink (zero thermal resistance) at this heatsink temperature coupled to the capacitor through its bottom insulation, allowing for the mounting hole if it's a stud mount, or 2. If 'C/W' is checked, a heatsink with this thermal resistance coupled to the air at the specified air temperature.

Applet Limitations and Cautionary Notes:

The applet comprises three models: impedance, thermal, and life. None of these models is perfect or exact. Since life is an exponential function of temperature, the error in predicting the life will be an exponential function of the error in predicting the core temperature. The ESR and thermal models (core heat rise above the ambient temperature) are generally each within 10% but have sometimes erred as much as 20%. For most applications where the ripple current is modest, this error does not cause an appreciable reduction in accuracy, but when the initial core rise is over 20 ºC, the possible error in calculating the life can be significant. Another source of error may occur when multiple capacitors are used in a bank or when the capacitors are placed in proximity to other hot components. These effects should be taken into account when entering the ambient air temperature for the capacitor. We encourage you to use the applet as a tool of modeling effects of heatsink, airflow, and capacitor characteristics, but we strongly recommend that you follow up with evaluating actual capacitors with thermocouples, especially if you are designing close to the performance limits.

Also note that there is little or no conservatism built into the applet, and the typical ESR is not a maximum ESR limit (the screw-terminal applet uses 70% of the limit as the typical ESR while the snapmount applet calculates the ESR from the foil surface area and electrolyte-paper properties), so remember to look at what the performance would be if the ESR were 40% higher than typical. Even though today's aluminum electrolytic capacitors are far advanced compared to the glycol-borate capacitors of the 1970's, the physics are essentially the same, and therefore the same old rules of thumb about 'lytics still apply: Derate the voltage and don't run them really hot if you want long life, good reliability, and robustness. Derating the DC voltage allows capacitors to handle line surges in modern systems with poor power quality, even when the capacitors are hot. Ensuring the capacitors run below 85 ºC will not only make them last longer by extending the wearout period, but will also keep your system out of trouble with random capacitor failures. Our aluminum electrolytic capacitors will generally run at failures rates in the 10-30 FIT (failures per billion unit hours) range at rated voltage, 45 ºC, but like wearout (life), the reliability is an exponential function of temperature, and a large bank (say 32 capacitors) running near rated voltage at 100 ºC is a recipe for a high rate of field failure, like 10% per year system failure rate.

Legal Disclaimer:

The CDE Capacitor Thermal/Life Calculator applets are not a contract, license, or authorization of any kind. Specifications and model are subject to change without notice. Cornell Dubilier assumes no liability on accuracy, completeness or suitability for any application. The only warranty is the one-year, application express warranty (copy available upon request).