Arnau Sans, Lead Engineer, HyTEPS
Supraharmonics refer to disturbances in electrical systems that occur within a specific frequency range: for 50 Hz European systems, this range is from 2.5 kHz to 150 kHz, while in 60 Hz systems, the range starts at 3.0 kHz. Not all electronics are the same, especially when it comes to how they convert AC to DC, or between AC systems. The differences lie in the type of electronics and semiconductors used, particularly their switching speeds. Most devices switch at a standard frequency of 16-20 kHz, but some operate at 3 kHz, which can pose safety risks. Some newer technologies work at even higher frequencies of 40-60 kHz.

Why does this matter? Higher switching frequencies enable the use of smaller, more advanced passive components – potentially increasing costs. However, they are also easier to filter using EMI filters, which are ineffective at low frequencies like 3 kHz and only minimally effective at 16-20 kHz. Ultimately, the choice of technology affects both performance and cost, as all systems inject certain frequencies into the environment.
Supraharmonics are becoming increasingly common in electrical installations for various reasons. Modern electrical systems are more complex. Basically, today’s processes require a more controllable load in order to adapt the power and rotation of a motor to exactly what is needed. In the past this couldn’t be controlled, but thank to electronics, it now can be. The higher the switching frequency, the more compact devices can be, since passive components become smaller. This leads to device interference, causing malfunctions, unintended activation of alarms, or power supply failures as capacitors (passive components) tend to absorb higher frequencies.
A major driver of increased supraharmonics is the widespread use of electronic equipment relying on power electronics with higher switching frequencies. Electronics have always been essential for solar panels, storage systems, and electric vehicles, as they operate on DC. These technologies didn’t exist previously. The challenge today is the growing number of such loads being connected across various systems. Modern electronic devices tend to be more sensitive to supraharmonics. Interference-related disturbances can lead to production losses (as a result of system shutdowns), as well as audible noise and vibrations in transformers, switchgear, and other electrical components. Noise in transformers is normally audible if the switching frequency is within the human hearing range (approximately from 20Hz to 16 kHz. However, some people can hear up to kHz-20 kHz and even higher frequencies. Persistent electromagnetic interference (EMI), voltage distortions and fluctuations, and harmonic resonances degrade component lifespans, system stability, and Power Quality.
Challenges in managing Supraharmonics
Historically, systems contained minimal electronics or none at all, and there was hardly any awareness that higher frequencies could cause problems. As a result, there is currently no comprehensive standardization or regulation regarding supraharmonic limits and mitigation. This means devices and systems are not always designed with adequate measures in mind.
Every device injects a certain level of supraharmonic current. When six identical loads are installed, higher harmonics will typically emerge. Ultimately, the degree of disturbance is affected by the extent to which the current builds up on the voltage waveform or the proximity of power cables to communication cables.
As power electronics become more prevalent, issues with supraharmonics are increasingly observed. Auxiliary loads, such as those close to battery inverters, can be more sensitive to disturbances. Supraharmonics can also propagate through a common ground, affecting loads such as computers and monitors. While traditional harmonic issues can be mitigated with techniques such as passive and active filters or intelligent electrical system designs, supraharmonics require different solutions since they cannot be addressed using conventional harmonic filters.
Solutions: smart analysis and specialized techniques
Measuring and mitigating supraharmonics requires specialized equipment. Standard power quality analyzers and harmonic meters are often inadequate for analyzing waveforms in this range. Addressing supraharmonic issues in electrical installations involves specialized methods and extensive expertise. Supraharmonics can vary significantly between installations, necessitating advanced monitoring, analysis tools, and specific training.
Experience, appropriate Power Quality meters, oscilloscopes, spectrum analyzers, and data collection and analysis, make it possible to identify supraharmonic frequencies and magnitudes and locate their sources and patterns. Based on this analysis, solutions such as EMI filters, shielding, and grounding can be implemented to attenuate unwanted frequencies and mitigate issues such as resonance.
The need for expertise and proactive measures
A thorough understanding of power quality issues, including supraharmonics, is essential to grasp the complex interactions between electrical system components and map the way in which these interactions cause or amplify supraharmonics. With the right expertise, it becomes possible to ensure that solutions comply with current and emerging regulations and best practices.
Working with specialists ensures that every step is executed effectively, resulting in improved Power Quality and reliable, long-lasting operation of electrical systems.