5000 amp 60 Hz 3-phase continuous current test of an enclosed 15 kV bus assembly

This paper describes the performance of a continuous current test on an enclosed 5000 amp (nonstandard rating) 60 Hz AC 15 kV bus assembly. The assembly includes terminations, wall penetrations, bus support insulators, and window-type current transformers. During the test procedure considerations for bus impedance (as it affects loading and balancing the current supply), current balancing, and parasitic heating of ferrous steel near the bus were some of the special problems encountered. In addition, the window-type current transformers had to be considered as they affected bus dimensions. Heat shrinkable insulation was used to provide the necessary dielectric insulation for the CTs. Forced air ventilation was used to limit temperature rise inside the enclosure. The quantity and method of ventilation was found to be critical to successful test results.