The 'IEC 61000-2-4' standard sets limits for industrial and non-public power distribution systems. It forms a guideline standard for many product and mechanical engineering standards and defines immunity levels of voltage distortion that machines and systems in industrial companies must comply with in all operating states. Exceeding these levels - especially over longer periods of time - leads to failures, unnecessary repair costs and possible production downtime. In order to ensure error-free operation of the installed system and machines, the voltage quality in all technical systems must be continuously monitored in accordance with IEC 61000-2-4. The Janitza app 'IEC 61000-2-4 WATCHDOG' automatically carries out the complex analysis of the measurement data for the user according to the limit values of the standard. The integrated visualization, which was designed according to the traffic light principle, allows immediate detection of violations of the limit values of the standard.