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Episode 6 Column
The main focus for this episode will be understanding the output “range” of various DC power supplies. It was not long ago that “single range” instruments were the industry standard and “range” wasn’t given much thought. However, with the advent of “wide range” power supplies, users now have to do a little bit of thinking when looking at the front panel specifications of their DC power supply (Ex: 0-40V/0-40A/400W) to know if they can obtain their desired voltage and current. This involves using the formula: Power (W) = Voltage (V) x Current (A).
Obviously, all DC power supplies have a limit to the amount of electrical energy that they can output. This is known as the rated output power. For example, the Kikusui PWR401L Wide-Range DC power supply has a rated output power of 400W. Furthermore, the voltage and current output ratings have an upper limit of 40V and 40A respectively. This means that although output at [40V x 10A = 400W] would be possible, [1V x 400A = 400W] would be exceeding the current limit.
Understanding “wide range” power supplies is easier when explained using a graph known as the “constant power curve,” which shows the relationship between current and voltage on the X and Y axes respectively while keeping a constant power. Although it sounds simple enough, it definitely takes some getting used to. After thinking long and hard, we decided to explain this concept with the chewy, elastic Japanese treat known as a “yokan” (a thick, gelatinous dessert made of bean paste and sugar). The yokan itself represents energy (power), whereas its length represents voltage and width represents current (we’ll ignore its weight for now). The average yokan is solid, meaning that its length and width are constant. You can think of this as “single range.” However, it’s difficult to eat as is, and needs to be cut and portioned appropriately. That being said, there are hidden rules dictating that you can’t eat the leftovers, unfortunately (as seen on page 13). So, how can you fully “master” the yokan (use the rated capacity efficiently without waste)?
When going to an amusement park or carnival, you often see stands selling churros, right? The first time I tried an actual churro, it was a bit of a surprise. It’s so much easier to eat than a traditional donut! Likewise, a fully elastic yokan that could flexibly stretch (adjust the voltage/current range) according to the size of your mouth (voltage and current load specifications) would be really easy to eat (use within the rated capacity without waste). This is basically what a “wide range” yokan would look like. So next time you hear about a “wide ranging” (or zoom, turbo, auto-ranging, etc.) power supply, try picturing a fully elastic treat like a Japanese yokan to help make things easier to wrap your head around.
Come to think of it, so many of the concepts throughout this comic book involve explanation through food (especially sweets) that I’m sure a lot of you are wondering whether this is a comic book or a food magazine… But please bear with us! The next episode has a little more of the same…