High-speed load-disconnects in redundant power system architectures.
Designers of high-availability systems understand that the costs of system down-time can have a devastating impact on their end-customer's business. For critical business and information systems such as data centers and networking and data storage systems, reliable redundant power is essential, and requires a careful analysis of each power stage and each potential mode of failure. In order to achieve up to 100 percent on-time, a design must be able to tolerate the failure of any single device. In some cases, that could include a failure of an output bus.
In basic terms, a redundant power system may consist of two or more power sources that terminate at common or redundant load points driven from the output buses. Higher power systems may consist of multiple conversion stages and/or large numbers of converters connected in parallel. Each conversion stage creates additional "output buses", which could also become shorted. In order to protect against having a shorted output bus potentially damage the other devices in the array, an electronic circuit breaker device can be used. The two most common types of electronic or "smart" circuit breakers include hot-swap and load-disconnect switch.
Comparison of a Load-Disconnect to a Hot-Swap Under a Fault Condition
Hot-swap solutions are designed primarily to limit potentially harmful transient currents of a board during insertion or removal from a live backplane, eliminating the need to shut down the entire system power during the installation. Hot-swap devices sense and limit a current surge for short intervals, but they can also be configured to latch off during a fault. A hot-swap circuit's response time to a short-circuit will depend on the period of time that it takes for the device to change from "normal mode" to "circuit breaker" mode, which is based on the timer circuit of the device.
Be sure to read the complete, online versions of this article at www.ecnmag.com/Design-Talk.aspx
By Chester Firek, Vicor Corporation, www.vicr.com
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|Title Annotation:||Design Innovations|
|Publication:||ECN-Electronic Component News|
|Date:||Nov 15, 2010|
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