Episode 5 Column
Episodes 5 and 6 (next episode) will focus on understanding “range” in DC power supplies. In episode 4, Minami learns the primary differences between “switching” and “linear” DC power supplies. Even after understanding these concepts, she was confused by new words thrown her way including “wide range”, “constant power”, and “single range” when going to provide support to her fellow engineer (Mr. Takabe). “Are there other DC power supply types apart from switching and linear?” This is something that often confuses beginners, as “switching” and “linear” are different circuit types, whereas “wide range” and “single range” are different methods of output. It’s important not to confuse these terms because they are identifying completely different power supply functions.
Now, the voltage and current range of a laboratory DC power supply is tied to its specifications. For example, a product like the PAS40-9 with “(0-40V, 0-9A)” on its front panel can output up to 40V of voltage and flow up to 9A of current. You probably think that this is incredibly obvious, but these trends are slowly changing. For example, a product like the PWR401L is specified at 0-40V, 0-40A, 400W. Traditionally, this would mean that the power supply can output 40V of voltage and 40A of current. However, this is not necessarily the case. Take a close look at the “400W” specification. The most important concept to understand when it comes to power supply range is the watt (or W, representing power).
When looking back at the history of laboratory DC power supplies, the concept of “range” didn’t even exist. Or rather, the vast majority of power supplies were “single range,” meaning that classification wasn’t even necessary. As some of you may remember from school: Power = Voltage x Current, meaning that the max output power for a power supply specified at (0-40V, 0-9A) would be [40 x 9 = 360 (W)], and there would be no reason to go out of your way to include this on the front panel. However, there are new products that have emerged in the 21st century that don’t follow this formula. These are commonly known as “wide ranging” DC power supplies. We refer to them as “wide range” power supplies, whereas other manufacturers refer to them as “zoom”, “auto-ranging”, or “turbo” power supplies; but the concept remains the same.
People who understand the concept behind wide-range power supplies will understand just how useful they are, but the uninitiated are likely to wonder why we have to go and make things so complicated. What’s wrong with the user-friendly, easy to understand single range DC power supplies anyway? Are manufacturers simply trying to push new products onto us!? To be completely honest, wide-ranging supplies are quite convenient from a manufacturer standpoint (they make for a much simpler product line-up), but the fact remains that many factors make these power supplies extremely convenient for the user. In the next episode (episode 6), we talk not only about the differences between the range types, but also discuss the advantages of wide-range and its developmental background.