Dynamic thermal ratings realize circuit load limits

Abstract

As economic pressure builds to fully utilize the capacity of existing power equipment, dynamic rating systems allow for informed decisions about circuit load limits. Dynamic thermal ratings offer a way to increase capacity under most weather- and load conditions while reducing the risk of failure under unfavorable conditions. EPRl's Dynamic Thermal Circuit Rating (DTCR) system makes thermal information readily available and provides a solid basis for higher equipment utilization. DTCR calculates dynamic thermal ratings (real-time ampacities) of power equipment based on actual load and weather conditions that are generally accessed through the utility's SCADA/EMS system. Given series or parallel combinations of equipment, the software determines dynamic circuit ratings by evaluating all equipment ratings on a circuit and finding the most limiting ampacity for each rating scenario. Dynamic ratings offer two key benefits over traditional static ratings: (1) higher loading of equipment is usually possible using actual measured load and weather parameters; traditional static ratings are overly conservative, since they are based on worst-case weather and load assumptions; and (2) a better understanding of equipment thermal response is achieved. This results in increased reliability.