Measurements with respect to the electromagnetic compatibility (EMC) of telecontrol systems in substations of medium-voltage distribution networks

In the construction of substations, electromagnetic compatibility has become more and more important due to the fact that modern microelectronic components are installed in the close surroundings of power engineering systems. Owing to the earthed enclosure of substations, telecontrol systems are installed directly next to the functional unit. Sources of interference, especially the switching operations of circuit breakers and disconnectors in the primary circuit, affect the process environment. The sources of interference (above all transient magnetic fields) endanger modern electronic elements via coupling devices. Secondary cables, current transformers and couplings in the functional units represent characteristic coupling devices. Measurements of 24 kV substations were made in order to determine transient magnetic field strengths in the room. The authors present experimental results and compare the behaviour of conventional and gas-insulated substations in relation to transient interference