Surge – also known as impulse voltage—describes sudden, brief but significant high-energy voltage increases in the electrical grid. These surges are usually caused by lightning strikes, switching operations in the power grid, or electrical disturbances that are fed into the system in an uncontrolled manner. Surge damage can then occur, particularly in sensitive electronic devices, and can even lead to total failure of the devices.

Lightning discharges are the most common cause of surge events. When lightning strikes near a power line, the voltage rises briefly to several thousand volts. These sudden surges spread along the line and can destroy electrical devices if they are not adequately protected.

Overvoltages are also caused by switching operations in the power grid, such as when large consumers are switched on or off or during switching operations at transmission stations. Such events are usually less extreme, but occur more frequently and can have a cumulative effect on the devices.

In addition to protecting the hardware, compliance with EMC directives and standards is also important. These standards, such as IEC 61000-4-5, specify test methods and limit values for surge events to ensure electromagnetic compatibility. They test how well an electrical system or device is protected against sudden voltage surges and whether a stable and defined operating state is maintained.

In the future, the importance of surge protection in EMC will continue to grow, especially with the expansion of renewable energies, smart grids, and the increasing networking of devices. This requires a combination of robust technical solutions and intelligent control to detect overvoltage peaks at an early stage and prevent damage to devices.

Conducted immunity is an important aspect of electromagnetic compatibility (EMC), which tests a system's ability to withstand electromagnetic interference coupled through cables without malfunctioning. In this context, the standards IEC 61000-4-6, IEC 61000-4-16 and IEC 61000-4-19 play a central role in the standardized evaluation and assurance of immunity.

IEC 61000-4-6 describes the environmental conditions and test methods for measuring strong fields coupled into wired devices. The aim is to evaluate resistance to high-frequency signals induced by electromagnetic fields in cable systems. Simulation and field tests are carried out in which interference in various frequency ranges is coupled into the cables in order to check the behavior of the devices under electromagnetic influences.

IEC 61000-4-16 covers the requirements for electromagnetic shielding and filtering of power and signal lines in the case of continuous disturbances. It specifies how tests are to be carried out to measure immunity to conducted, asymmetrical disturbances in the frequency range from 0 Hz to 150 kHz. The aim is to develop devices in such a way that interference from external electromagnetic fields, for example in industrial environments, does not affect their function. Measures such as filters, shielding, and grounding concepts are evaluated in this context.

Finally, IEC 61000-4-19 specifies the test procedures for conducted immunity at AC mains connections against conducted symmetrical disturbances and disturbances from signal transmission in the frequency range from 2 kHz to 150 kHz. These tests simulate real-world loads and test whether systems and devices can withstand these impulses without permanent damage or functional impairment.

In practice, these standards form the basis for the design, testing, and certification of electronic systems with regard to their resistance to conducted electromagnetic interference. Protective measures such as filter circuits, grounding concepts, or soft switching tactics are essential in this context. Compliance with these standards plays a decisive role in minimizing interference and ensuring operational safety in electromagnetically stressed environments.