"A countrywide blackout has been caused by a sudden plunge in the frequency in the power transmission system," Pakistan's power minister, Omar Ayub Khan, wrote on Twitter in the early hours of Sunday. He added that the outage occurred after a fault developed at the Guddu power plant in Sindh province shortly before midnight on Saturday (9th Jan 2021). Consider you have to provide consultancy services as Transmission Design Engineer for the transparent investigation , being the technical member of the Investigation Commission in this regard. Following facts & Figures have been provided/claimed to you by NTDC Pakistan. The major Fault developed in Guddu-Power Plant was partially cleared by the Protective Devices and partially not cleared at all , due to which a Switching Surge of (LSD)110 KV travelled in an overhead line (Primary Line) having the Natural Impedance of 500 thereby reaching the junction of the two parallel dividing branch lines as shown in Figure (1). One branch-line known as Guddu-Line, supplying to Guddu-Substation is being terminated with a short piece of Underground-cable having inductance/Km as 2.(LSD) H and capacitance/Km a as 0.(LSD) F while the 2nd branch-line known as Dadu-Line , supplying to Dadu-Substation is connected to a Surge-Arrestor of 40 . Both Guddu Line & Daddu Line has conductors 1.(LSD) cm in diameter 1.(SS) metre apart in equilateral formation. Figure (1): Transmission System for Blackout-Problem Page 3 of 9 Analyze the following Electrical characteristics of the Switching Surges traveling from Primary Overhead T/X line to Guddu Substation & Dadu Substation as follows; (a) The Voltage & Current of Transmitted Surge Waves in both Guddu & Daddu branch Lines (b) The voltage & current of backward Surge Waves in Guddu-Line which are basically reflected from UG-Cable . (c) The Voltage & Current of the surge-waves diverted by the Surge-Arrestor to Ground in Dadu Line Case. (d) The power of Surge-wave diverted to Ground in Dadu Line Case.