The Analysis of the Effectiveness of Standard Protection Devices in Supply Systems Fed from Synchronous Generator Sets

摘要

The paper analyses the effectiveness of the human protection against electric shock in circuits fed from the generator, especially from the backup generation set. Several protection devices of different characteristics were tested in laboratory and new approach to the protection was proposed in TN type wiring (earthed neutral point arrangement). This happened due to the fact that measurements showed that actually used devices do not satisfy protection criteria when full power of the generator is used. This criteria include time criterion - the maximum time of the occurrence of touching overvoltage can occur in less than 0.4 s time period. The proposal include new approach to the short circuit detection, where not only current but also voltage sensing is used. For a IT wiring (system insulated from the ground) “ 0 ” symmetrical component sensing an insulation testing devices are proposed.