Document Type

Thesis - Open Access

Award Date


Degree Name

Master of Science (MS)


Electrical Engineering


All the electrical equipment involved in the generation, transmission, and distribution of electrical energy is exposed to switching surges and the effects of lightning voltages to some degree. Even the most modern protective devices, such as lightning arrestors, require a finite time to operate. Thus the insulation in generators, transformers, and switchgear must withstand high impulse voltages for the very short time required for protective devices to conduct the lightning voltages and switching surges to ground. The use of gases as insulation in electrical equipment offers certain advantages over the more conventional liquids and solids. In recent years attempts to utilize gases in such applications has led to the investigation and development of gases with particularly high electric strength as compared to air. Testing has been carried on with such gases as C3F8, C4F8, SF6, and NF3. These tests have been done in the areas of lightning impulses and 60 cycles. The next stop is to extend the work by using wave shapes between these two extremes and compare their breakdown strengths to the two extremes. Very little has been done in this intermediate range with gases. This intermediate range covers switching surges which can cause extensive damage to electrical equipment and is currently receiving considerable attention insulation evaluation.

Library of Congress Subject Headings

Electric discharges through gases
Electric conductivity
Ionization of gases




South Dakota State University