The effect of inhomogeneous ambient conditions on air clearances in high voltage laboratories

High voltage laboratories are designed to have sufficient clearances to avoid undesired flashovers from generator surfaces. However, numerous factors influence the characteristics of breakdown in air, including ambient conditions such as temperature, pressure, and humidity. If the laboratory environment is not adequately controlled, ambient conditions could deviate as a function of elevation and result in insufficient clearances at the highest points of large generators where voltage stress is also the greatest. Ambient conditions were mapped at the Aalto University high voltage laboratory in Finland and compared with data obtained at the Mississippi State University (USA) laboratory. Both laboratories are of comparable size, however, differences exist in building design and air regulation. Despite these differences, both laboratories showed minimal fluctuations in temperature at different locations and elevations.