Ignition of Hydrogen/Air Mixtures through Electric Discharges at High Frequency AC Voltage

The ignition of hydrogen/air mixtures through pre or partial discharges at high‐frequency alternating voltage is still not sufficiently understood. In this contribution, the ignition process is examined with respect to voltage amplitude, gap distance, and number of cycles. It is shown that the energy of several discharges can accumulate, leading to a temperature rise which may cause ignition. It can be concluded that the requirement “transient overvoltages need not be taken into account” is not tenable for all voltage levels. Therefore, the requirements concerning the dimensioning of creepage distances and clearances within the “increased safety” type of protection “e” has to be adjusted with respect to IEC 60079‐7.