Grounding problems and unwanted noise in electrical systems can often lead to insanity. It can seem like there’s no method to the madness when an electrical “gremlin” caused by one of these things pops its head out. When looking more closely, however, these issues have a way of becoming more obvious. In a recent video, [Fesz Electronics] shows us how to investigate some of these problems by looking at a small desktop power supply, modelling it in LTSpice, and reducing the noise on the power supply’s output.
While everything in this setup is properly grounded, including the power supply and oscilloscope, the way the grounding systems interact can contribute to the high amount of noise. This was discovered by isolating the power supply from earth ground using electrical tape (not recommended as a long-term solution) and seeing that the noise was reduced. However, the ripple increased substantially, so a more permanent fix was needed. For that, the power supply was modelled in LTSpice. This is where a key discovery was made: since all the parts of the power supply aren’t ideal, noise can be introduced from the actual real-life electrical behavior of some of the parts. In this case, it was non-ideal capacitance in the transformer.
According to the model, this power supply could be improved by adding a larger capacitor across the output leads, and also by increasing their inductance. A large capacitor was soldered in the power supply and an iron ferrule was added, which decreased the noise level from 100 mV to around 20. Still not perfect, but a much needed improvement to the simple power supply. If, on the other hand, you want to make sure you eliminate that transformer’s capacitance completely, you can always go with a transformerless power supply. That carries other risks, though.
Renewable energy has long been touted as a major requirement in the fight to stave off the world’s growing climate emergency. Governments have been slow to act, but prices continue to come down and the case for renewables grows stronger by the day.
However, renewables have always struggled around the issue of availability. Solar power only works when the sun is shining, and wind generators only when the wind is blowing. The obvious solution is to create some kind of large, grid-connected battery to store excess energy in off-peak periods, and use it to prop up the grid when renewable outputs are low. These days, that’s actually a viable idea, as South Australia proved in 2017.
As the global climate emergency continues to loom over human civilization, feverish work is underway around the world to find technical and political solutions to the problem. Much has been gained in recent years, but as global emissions continue to increase, there remains much left to do to stave off the most catastrophic effects of climate change.
Renewable energy has led the charge, allowing humanity to continue to enjoy the wonders of electricity with a reduced environmental impact. The future looks promising, with renewable sources becoming cheaper than traditional fossil fuel energy plants in many cases, both in the USand abroad. At the same time, the rise of renewable technologies has brought new and varied challenges to the fore, which must be dealt with in kind. Take wind energy, for instance. Continue reading “What Will We Do With The Turbine Blades?”→
[Practical Engineering] is ready to explain how power substations get electricity to you in his latest video, which you can see below. One of the things we always notice when talking to people either in our community or outside it is that most people have no idea how most of the modern world works.
Ask your non-technical friend to explain how a cell phone works or how a hard drive stores data and you aren’t likely to get a very good answer. However, even most of us are only focused on some particular aspect of electronics. There are a lot of people who hack on robots or radios. The AC power grid,though isn’t something a lot of people work with as a hobby. Do you know exactly what goes on in that substation you pass every day on your commute? If you don’t, you’ll learn something in the video.
Of all the fictional cyborgs who turn against humanity to conquer the planet, this is as far from that possibility as you can get. These harmless mushrooms seem more interested in showing off their excellent fashion sense with a daring juxtaposition of hard grid lines with playful spirals. But the purpose of this bacteria-fungus-technology hybrid is to generate electricity. The mushrooms are there to play nurse to a layer of cyanobacteria, the green gel in the photo, while the straight black lines harvest electricity.
Cyanobacteria do not live very long under these kinds of conditions, so long-term use is out of the question, but by giving the cyanobacteria somewhere it can thrive, the usefulness grows. The interplay between bacterial and supportive organics could lead to advances in sensors and hydrogels as well. At some point, we may grow some of our hardware and a green thumb will be as useful as a degree in computer science.
Current. Too little of it, and you can’t get where you’re going, too much and your hardware’s on fire. In many projects, it’s desirable to know just how much current is being drawn, and even more desirable to limit it to avoid catastrophic destruction. The humble current shunt is an excellent way to do just that.
To understand current, it’s important to understand Ohm’s Law, which defines the relationship between current, voltage, and resistance. If we know two out of the three, we can calculate the unknown. This is the underlying principle behind the current shunt. A current flows through a resistor, and the voltage drop across the resistor is measured. If the resistance also is known, the current can be calculated with the equation I=V/R.
This simple fact can be used to great effect. As an example, consider a microcontroller used to control a DC motor with a transistor controlled by a PWM output. A known resistance is placed inline with the motor and, the voltage drop across it measured with the onboard analog-to-digital converter. With a few lines of code, it’s simple for the microcontroller to calculate the current flowing to the motor. Armed with this knowledge, code can be crafted to limit the motor current draw for such purposes as avoiding overheating the motor, or to protect the drive transistors from failure.
In fact, such strategies can be used in a wide variety of applications. In microcontroller projects you can measure as many currents as you have spare ADC channels and time. Whether you’re driving high power LEDs or trying to build protection into a power supply, current shunts are key to doing this.
After two massive hurricanes impacted Puerto Rico three months ago, the island was left with extensive damage to its electrical infrastructure. Part of the problem was that the infrastructure was woefully inadequate to withstand a hurricane impact at all. It is possible to harden buildings and infrastructure against extreme weather, and a new plan to restore Puerto Rico’s power grid will address many of these changes that, frankly, should have been made long ago.
Among the upgrades to the power distribution system are improvements to SCADA systems. SCADA allows for remote monitoring and control of substations, switchgear, and other equipment which minimizes the need for crews to investigate problems and improves reliability. SCADA can also be used for automation on a large scale, in addition to the installation of other autonomous equipment meant to isolate faults and restore power quickly. The grid will get physical upgrades as well, including equipment like poles, wire, and substations that are designed and installed to a more rigorous standard in order to make them more wind- and flood-tolerant. Additional infrastructure will be placed underground as well, and a more aggressive tree trimming program will be put in place.
The plan also calls for some 21st-century improvements as well, including the implementation of “micro grids”. These micro grids reduce the power system’s reliance on centralized power plants by placing small generation facilities (generators, rooftop solar, etc) in critical areas, like at hospitals. Micro grids can also be used in remote areas to improve reliability where it is often impractical or uneconomical to service.
While hurricanes are inevitable in certain parts of the world, the damage that they cause is often exacerbated by poor design and bad planning. Especially in the mysterious world of power generation and distribution, a robust infrastructure is extremely important for the health, safety, and well-being of the people who rely on it. Hopefully these steps will improve Puerto Rico’s situation, especially since this won’t be the last time a major storm impacts the island.