Abnormal switching transients are those transients that arise during unbalanced faults interruption e.g., single-line-to-ground (S.L.G) fault, double-line-to-ground (D.L.G) fault, or three-phase fault. Circuit-breaker is the first line of defense to face these abnormal transients. Whenever a circuit-breaker encounters these abnormal transients, it changes its state from close to open by moving away its closed contacts. Circuit-breaker try to block large amount of fault-current from flowing, and these transients appear in the form of multitude-voltage around circuit-breaker’ open contacts. This large amount of voltage is known as transient recovery voltage (T.R.V). This T.R.V is normally three to five-times of the rated operating voltage. Circuit-breaker failure/damage occurs only when it is unable to withstand this T.R.V for which it is designed. In this research, methodology is developed to correctly find the value of T.R.V by taking care of various abnormal and worst-case switching scenarios. T.R.V curtailment is a serious challenge for the power system experts. This study is a competent effort to address this challenge. Electromagnetic-Alternative Transient Program (EM-A.T.P) software is used for simulation of the test network IEEE-39 bus system.
Rahman Ullah Khan and Abdual Basit Methodology to find and mitigate Transient Recovery Voltages (T.R.V) considering various abnorma A case study of IEEE-39 bus system International Journal of Engineering Works Vol. 6 Issue 12 PP. 556-563 December 2019