What is Electrical Noise and How Can You Prevent It?
In music and everyday life, a tone represents a harmonic sound that sounds good to our ears. The noise, however, is the disharmonic sound that’s everything but desirable. When it comes to the electricity, we can only identify with the noise, as it’s something that can cause you a lot of trouble. This noise is sometimes called ‘electromagnetic interference’ and can disrupt the normal workflow of your measuring instruments such as sensors, for example.
Despite the fact that it doesn’t sound too critical or scary, you’ll still need to protect your electrical devices from the noise. Luckily for you, we’re going to explain what exactly is noise and how you can prevent it.
What is Electric Noise?
Simply put, the electric noise is a disturbance in an electric that causes changes in voltage or current. As we’re talking about the unwanted disturbance, its pattern is often random, sporadic, and can’t be foreseen. When the electric noise occurs, we can always notice a sudden, yet a short increase of voltage or current by a small margin – at least, in most cases. The amplitude of electric noise isn’t that high, in fact, it’s very low, but it can easily damage your electronic devices if not remedied as soon as possible.
Causes and Types of Noise
When it comes to the cause of the noise, there are a lot of different causes for it. Sometimes it’s the faulty power supply, sometimes it’s a resistor, and sometimes it’s simply unknown! However, we can identify several types of noise that can help us in mitigating it before it’s too late.
Thermal Noise (Johnson-Nyquist Noise)
Thermal noise is unavoidable and is directly associated with the flow of electrons inside the electrical conductor. Related to resistance, bandwidth, and temperature, this type of noise is manifested as voltage variations that occur randomly.
The thermal noise is always here since conductors have some amount of resistance, unless we speak about superconductors, with much lower values of resistance. Circuits are made of conductors and not superconductors, which is why we have thermal noise.
Flicker Noise (1/f Noise)
Flicker noise or 1/f noise is a type of noise that occurs in the vast majority of electronic devices. The causes of flicker noise are impurities, recombination, and generation noise, especially in transistors. Flicker noise is simply a signal with a frequency spectrum that slowly raises to the higher frequencies. As the frequency increases, the amplitude decreases, which is why it’s called “1/f”, a name which implies to the relationship between amplitude and frequency.
Shot noise is a bit harder to explain, but we’ll do it in the most comprehensive way possible. In electronic devices, the shot noise is a byproduct of random statistical fluctuations of the current when electrons traverse a gap. When an electron crosses a barrier, they always have a discrete arrival time – an effect which produces shot noise.
Much like the thermal noise, shot noise is unavoidable.
Every electronic system consists of various components including semiconductors. Unfortunately, burst noise plagues only these semiconductors which are, needless to say – ubiquitous and obligatory. Usually caused by the imperfection of the semiconductor materials, burst noise represents voltage or current transitions, which can even be heard by amplifying a contaminated signal.
When transferred to a speaker, this signal sounds like popcorn popping, which is why this type of noise is sometimes called ‘popcorn noise’.
How to Prevent Electric Noise?
Despite having some unavoidable noises, you can still protect your electrical installation from the avoidable noises, as well as mitigate the unavoidable ones. Here are some tips on how to do it:
- Route your Cables
- Cable Shielding
- Proper Grounding
Many electricians will work on the electric installation and leave the cables hanging around, which is a terrible thing to do if you want to prevent noise. Let’s say we have a signal cable and an electrical cable. Routing the signal cable next to power sources or even an electrical cable is wrong as it can disrupt the signals and induce electric noises. For example, an electric motor produces a magnetic field which can increase voltages and higher voltages mean higher electric noise.
That being said, never tie your signal and electrical cable together. Any electronic component that produces a magnetic field needs to be distanced from the signal cable.
Cable shielding is something that’s better done by a professional. As much as it’s a simple thing to do, it’s heavily overlooked and is one of the most common causes of electrical noise. A tidy instrumentation wiring is always desirable, especially when we’re talking about shielding your cables in various power outlets and appliances. If you can’t do it alone, you can always play it safe and use recommendations from the manufacturer.
If you are working with a lot of sensors in your electrical installation, you should know that the ground carries a large portion of electrical noise away from the system. A drain wire should be connected to the ground on one side, and on the other, it should have a contact with a drain wire. This allows the noise to travel directly to the ground using a drain wire, instead of the signal wire.
Proper grounding should be your top priority. Not only that it protects from the electrical noise, but also from a power surge, which can completely destroy your electrical system.
Now that we covered everything you need to know about electrical noise, we hope you’ll take the necessary precautions to reduce it. It’s a physical phenomenon that still concerns electrical engineers, yet many people didn’t even hear about it. While some types can be eliminated, most types of electrical noise are present and can only be reduced.
The important thing is to always use a proper grounding technique, shield your cables, and follow proper routing standards. This will ensure that the noise is reduced to a minimum.