Influence of serial choke on damping of switching transients in distribution transformers

Distribution transformers operating in modern system grids or in industrial networks are subjected to many switching transients. They may occur due to routine operations, network reconfigurations or reaction on protection signals. Depending on the network configuration and parameters such events my lead to external overvoltages and result in additional stresses on the insulation system. The paper presents influence of serial choke on damping of switching transients in distribution transformers. The suppression of transient rise time will be shown in configuration involving distribution transformers connected to low loss cable lines and medium voltage breaker. Such phenomena are especially typical for industrial networks where switching operations are very frequent. The protection of distribution transformers with a serial choke is a new approach dedicated to environment prone to transients characterized by high steepness. The impact of the choke will be assessed by both amplitude and rise time reduction.