Power Electronics

The Payoffs and Perils of Power-Supply Crossover

Power supplies like many other components, often find a life beyond their intended applications. Customers in search of supplies for their niche designs frequently discover that off-the-shelf power supplies will work adequately in their designs. Sometimes a whole new set of applications is found for a particular type of power supply.

I discovered this recently while speaking to makers of DIN rail-mounted power supplies. Several vendors noted that these supplies, which were first developed to power industrial devices such as PLCs, have begun to appear in telecom, transportation and aerospace applications. System designers in those fields appreciated the DIN rail supply's ease of assembly, full-power output over temperature with only convection cooling, and low cost. These same designers were willing to sacrifice some power density to get those benefits.

Intrigued by the DIN rail supply's crossover from industrial to other fields, I asked supply manufacturers about similar trends among other power-supply types.

At Artesyn Technologies, it was noted that ac-dc supplies developed for computing equipment were making their way into storage switch or test equipment because of a similar power architecture using a 12-V bus and similar environmental specifications.

Meanwhile, several vendors pointed out that dc-dc converters designed primarily for telecom have migrated into other areas with the transition from centralized power architectures to distributed power. SynQor's Eric Olson enumerated some of the non-telecom applications for the board-mounted power converters: industrial process controls, automatic test equipment, transportation systems, agricultural and mining equipment, marine products, broadcasting, medical monitors, and military applications.

At Artesyn, Conor Quinn noted that some of the dc-dc converters developed for telecom have been adopted in blade servers. As in the telecom designs, low profile and high efficiency makes these converters suitable for the densely packed blade servers. In contrast, the dc-dc converters developed for use in rack-mount and pedestal servers were designed to operate with greater airflow and were therefore optimized more for cost than efficiency.

Of course, attempts to redirect existing power-supply products into new applications are not always successful. David Norton of Lambda recalled how one customer designed out a convection-cooled “light-industrial” 5-V 10-A supply in favor of another vendor's 250-W PC supply. According to Norton, “The new supply came fully enclosed and fan cooled with wiring harnesses included at a fraction of the cost. Six months later we got a call asking for a quantity buy of our supply for a field retrofit as they were experiencing high field failures of the PC supply.”

Supply chain considerations also can override the potential benefits of using an otherwise mainstream product outside its intended application. As Norton observed, this has occurred as some industrial users tried “to ride the coattails of the PC power-supply industry,” despite discrepancies in the expected life spans of the end products. Industrial equipment may have a life expectancy of 8 to 10 years versus 18 to 24 months for many PC products. “Often, by the time the industrial customer has approvals on a product, the PC power supply is no longer available!”

Ultimately, the ability of one type of supply to migrate from one field to another will hinge on the customer's acceptance of the necessary tradeoffs, particularly when an existing supply is ordered “as is.” The design often hinges on the expected production levels. As Quinn says, “If you're going to be successful in high-volume applications, you have to go with optimization. It always comes back to cost versus volume.”

Despite the potential pitfalls, redirecting power supplies for one application into another has many potential benefits for both suppliers and customers. In addition to growing the business for a given product type and satisfying customer requirements, it may ultimately lead to customization of existing power supplies and create new standard products. What do you think? E-mail your comments to [email protected].

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