Measuring and analysing high frequency currents and voltages.

At HyTEPS, we have noticed an increasing number of complaints from the industry regarding high frequency currents and voltages.  We cannot restrict ourselves to measuring only the regular harmonic voltages and currents, which are defined up to a frequency of 2.5kHz, the 50th harmonic.

A great many power electronic devices (for instance variable frequency drives, Solar panel system inverters and electric vehicle chargers) work at a high switching frequency of tens of kilohertz. Often, these devices operate at switching frequencies of 5kHz, 10kHz, 15kHz or even higher.

Supraharmonic voltages produced by an electric vehicle

Such high frequencies in the current lead to high frequent voltages in the installation, which can affect the proper functioning or control of an installation. In severe cases, it may also lead to a shortened equipment lifespan. Due to the high frequency, problems are often only local. Since the transformers present a high resistance path for high frequencies, high frequency currents tend to find a path through the capacitors in the filters of other devices. Capacitors have a low impedance for high frequency signals.

path of a high frequency current to earth

To measure these high frequency currents, special measurement devices are required. However, the measurement transformers need to be suitable for high frequencies. HyTEPS can find and map these distortions. Subsequently, analysis is performed to find possible solutions to combat the distortions.

Improvements to rules and regulations are also necessary when it comes to ensuring immunity and emission in this frequency range. This provides a clue as to why it is so difficult to find the party responsible for this phenomena.

The most important part is to be conscious of which distortions arise at these high frequencies and what the source of the distortions is. A clear analysis, required to determine the source and where the affected devices are, is the first step.

HyTEPS is expert in problems caused by high frequency harmonics


With the help of advanced simulation software packages HyTEPS can determine the impact of a mitigation, and arrive at the best solution. A major part of the installation should be modelled to gain a clear insight into the path that the high frequency currents can take.

Do not be taken by surprised when it comes to this source of problems - ensure that you have proper insight into what is happening in your installation!

Ask an Power Quality Expert