How to create EMC-compliant systems

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Drive Technology | Technology

Tim Schöllmann | 23.07.2026

KEB supports machine builders with EMC questions

In machine engineering, the number of electronic components is constantly increasing. When a wide variety of technical components interact, they can influence one another – leading to challenges regarding electromagnetic compatibility (EMC). Therefore, it is advisable to take EMC requirements into account right from the initial stages of machine design.

Especially in the early phases of machine development, it is cost-effective to ensure an optimal EMC-compliant design. This leads to increased immunity to interference, which has a positive effect on machine availability. It also prevents problems related to the machine’s emission of interference. KEB Automation supports users in various ways to design systems that comply with EMC standards.

Compact high-frequency (HF) filter technology for long cable lengths

KEB offers plant and machine builders drive controllers with internal (COMBIVERT G6, COMBIVERT S6) and external (COMBIVERT F6) filter technology (XXE6T60XXXX series). These solutions enable flexible adaptation to a wide variety of applications. As a result, all regulatory requirements can be met, even for very long motor cable lengths. A distinctive feature of the internal and external filters is that they suppress the differential current generated by the drive converter, allowing the drives to be protected by residual current devices (RCDs). Consequently, KEB’s drive technology enables solutions in the areas of fire protection (≤300 mA) and personal safety.

The external filters are available in various designs. “Under-mount filters,” for example, enable a particularly space-saving installation by mounting the drive on top of the filter. “Side-mount filters,” on the other hand, are used not only for individual interference suppression but also for total interference suppression and as control cabinet filters.

Harmonic Reduction

State-of-the-art drive inverters feature a built-in mains rectifier and a DC link circuit. This configuration results in current distortions (harmonics) that propagate through the power supply network. Power supply networks are designed for operation at their rated frequencies (50/60 Hz). Harmonic currents in the power supply network therefore increase losses in the lines, fuses, power transformers, and loads. The line chokes offered by KEB (XXZ1B0410XX series) are matched to the drive controllers and provide an optimal price-performance ratio for reducing current harmonics. By reducing the ripple current in the mains rectifier and in the DC link capacitors, the maximum service life of the DC link is achieved. If a further reduction in mains harmonics is required, this can be achieved using the KEB harmonic filters.

The KEB harmonic filter (XXZ1C0X10XX) ensures a THD-I ≤ 8 percent. KEB’s patented design offers both economic and technical advantages over the competition. For example, the required inductors are mounted on a single core, which reduces the required installation space and enhances the filter’s performance. With this harmonic filter solution, even high-power drive inverters can be operated on comparatively weak power grids (e.g., generator grids). With both solutions, KEB is always able to offer the most cost-effective solution for every application while ensuring compliance with international standards.

Requirements Due to PWM

Today’s drive inverters feature a pulse-width-modulated (PWM) output signal. KEB drives are configured with a reduced edge steepness to minimize stress on the motor insulation and reduce the occurrence of bearing currents. For special applications with particularly long motor lead lengths, KEB offers a range of motor filters. These include motor chokes and sine wave filters, which are available for all adjustable output frequencies up to 1600 Hz.

These filters can also be used for specific motors that require a reduction in the switching-frequency component of the PWM signal to enable operation with the drive inverter. These components can be completely filtered out of the signal – particularly using sine wave filters – so that the motor is supplied with a pure sine wave signal. As a result, motor losses are significantly reduced.