Switchgear with advanced surge protection in 40 kV network

In order to optimize future investments in the Swedish 40 kV distribution network, Vattenfall Distribution decided to investigate the possibility to lower the insulation level of substation equipment by advanced surge protection. Historically, Vattenfall´s 40 kV substations in Sweden have the rated voltage 52 kV which is a rare voltage. As equipment for 36 kV and 40.5 kV is more frequently used, Vattenfall wanted to know the possibility to use equipment for these voltages in the network and, if so, identify necessary adaptions. Insulation studies have been performed with positive result. Substations with switchgears of new design were built and are successful in operation.