Field application of a dynamic thermal circuit rating method

The thermal capacity of power equipment has been traditionally based on simultaneous occurrence of worst case weather conditions and peak loadings. A dynamic thermal rating method has been developed where the thermal capacity of power equipment is based on actual realtime weather conditions and circuit loadings. This normally results in higher thermal ratings which may allow the power utility to postpone replacement of underground cables and substation equipment or reconstruction of overhead lines. It may also allow immediate increased access to low cost power sources. This paper describes the technical philosophy and field data collection plan necessary to apply the EPRI Dynamic Thermal Circuit Rating Methods to overhead lines within the PECO Energy transmission area. It also briefly describes field test management for a power transformer and an underground cable in the same transmission system.