| dc.description.abstract | Working group A3.36 from Cigré is studying to what degree simulations can be used to predict the steady state temperature of MV and HV switchgear. The result of this thesis will be provided to the working group. The aim of the thesis is to assemble a realistic test device, which has a realistic design, power input and number of contacts/connections. The test device consists of a three-phase setup with knife switches inside an enclosure without ventilation.
Tests have been performed on the test device to find the bulk and contact resistance and compared the bulk resistance to the theoretical value, the power loss is estimated, and the steady state temperature is found. Two temperature rise tests have been performed, one with magnetic bolts and washers in the bushings and one with nonmagnetic bolts and washers.
It was found large variations in the contact resistances of the rotating contacts of the knife switches, the steady state temperatures of the current path were found to be higher than the temperatures of similar switchgears, even though the power loss of the test device is less than the power loss in the similar switchgear. The magnetic bolts had an impact of the heat generation of the conductors, when the bolts were replaced with nonmagnetic bolts the steady state temperature decreased and the power loss stayed approximately the same. The IEC temperature limits were exceeded by great extent in both tests. Overall, the temperature of the current path should be reduced for the test device to be more realistic. | nb_NO |
