Power Supplies

Almost every piece of equipment—from a computer to an oscilloscope and beyond—uses a power supply. Scientists expect power supplies to keep going and going. Luckily, most of them do. Those power plants inside devices, though, come in a wide assortment.

Although the primary job of power supplies is making power, scientists want them using less of it. “There’s a dramatic shift in interest, from a cost perspective, toward power reduction and understanding the power requirements,” says Mark Swift, marketing manager at Universal Electric Corporation (Canonsburg, PA). “There’s lots of power-monitoring equipment being installed.”

In many cases, improving power efficiency spurs more funding. As Swift explains, “Lots of funding is tied to reductions in power usage, so there’s a need to see where you’re starting from before you can put together a plan to reduce it.” That plan often includes selecting new power supplies that are more efficient.

Beyond efficiency, Swift encourages customers to buy flexible power systems. “A myriad of power requirements for supplies exist in almost every lab,” he says. “Plus you need to be able to repurpose a lab for different kinds of work.”
Specific specs

In a lab, scientists often build one-off devices. Maybe it’s an experimental device or a prototype for a production concept. Either way, such devices almost always need power. EMCO High Voltage Corporation (Sutter Creek, CA) makes power supplies for those applications—putting a supply in other instruments. Those might go to companies making thousands of one type of device or to a bench scientist working on one experimental instrument. “A lot of our customers are the instrument manufacturers themselves,” says Joel Huang, applications engineer at EMCO High Voltage Corporation.

As described by Huang, “Our power supplies provide a high voltage from a low voltage,” which is frequently needed. For example, Huang says, “High voltage is required in equipment for sorting cells or separating compounds or DNA.” Many chemical applications also need high voltage.

Huang says, “Our products produce fairly low power, but they come in a wide range of input and output voltages." The EMCO power supplies use 5–24 volts as inputs and produce 100–33,000 volts as output. Huang says, “We have about 5,000 models, because for a given series there’s a model that takes in 12 volts and gives 300, then one that takes 5 volts and gives 800, and so on.” He adds, “The power levels vary from 0.5 to 15 watts. The smaller supplies can be treated as [printed circuit board] components.”
Keep putting out the power

Overall, power supplies don’t need much attention. “Once a power supply is in the system, unless you overstress it significantly, you don’t need to take care of it in any way,” Huang says. “It just works.”

Bruce Land, senior lecturer at Cornell University’s school of computer and electrical engineering (Ithaca, NY) says, “For teaching student labs, good voltage regulation and easy controls are useful, but bulletproof current limiting is very important.” He adds, “Students do the weirdest things, like short the 5-volt supply to the 12-volt supply.” As an example, he says, “One power supply we used years ago failed in this mode by melting the solder holding the 12-volt regulator on the board!” So, super-robust power supplies make the best choices.

Article courtesy of Lab Manager Magazine.

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