Conference proceedings article
Selection of a switching element to characterise the dynamic behaviour of dc sources

Publication Details
Wiens, C.; Claudi, A.
University of West Bohemia, Pilsen
Publication year:
Pages range:
Book title:
19th International Symposium on High Voltage Engineering
Volume number:

The increasing number of DC-applications demand new requirements to switching elements. Especially for surge protective devices the power which they have to handle is dependent on the different kind of DC sources. For this reason the dynamic behavior of the source has to be determined reliably. This paper describes the important values for switching devices in DC sources. Furthermore the selection of a switching element for DC circuits is described. Due to the low switching times semiconductor switches are suited for determining the time constant of DC circuits. In addition with semiconductor switches there are no arcs during the switch-off moment, whose extinction would cause problems at the DC source. Concurrently the low switching times are also bringing problems. During the switch-off moment large over-voltages occur, which make a determination of the dynamic behavior difficult. To protect the devices a surge protective device must be used. For this purpose a metal oxide varistor is used, it can switch off safely without zero crossings. Investigations, described in this paper are showing that the limiting voltage rise increases with increasing switch-off currents. The duration of the overvoltage increases also, so the dynamic behavior during the switch-off moment can't be determined accurately. Switching devices with longer switching times have to be used, to ensure that no over-voltages can occur. Thus an evaluation of current and voltage can be performed without the influences of the over-voltage and the dynamic behavior can be determined.


Last updated on 2019-25-07 at 11:52