Final Exam Tutorial Session Problems and Solutions Summer 2023

PwnHero Tutorial Session - Final Exam ELE637: Energy Conversion Summer 2023 1- A 400-MVA, 240-kV/24-KV, three-phase Y- Δ transformer has an equivalent series impedance of 1.2 + j6 - per phase referred to the high-voltage side. The transformer is supplying a three-phase load of 400 MVA, 0.8 power factor lagging at a terminal voltage of 24 kV (line to line) on its low-voltage side. The primary is supplied from a feeder with an impedance of 0.6 + j1.2 - per phase. Determine the line-to-line voltage at the high-voltage terminals of the transformer and the sending-end of the feeder. 2-A Δ-Y connected bank of three identical 100-kVA, 2400-V/120-V, 60-Hz transformers is supplied with power through a feeder whose impedance is 0.065 + j0.870 Ω per phase. The equivalent series impedance of each 1φ transformer referred to the low-voltage side is 0.0012+j0.003 Ω. The voltage at the sending end of the feeder is held constant at 2400 V line-to-line. The load can be modeled as three equal impedances connected in Δ from. Each phase impedance ZL is equal to 0.410+j0.135 Ω. Determine: (a) The load line-to-line voltage, (b) The transformer windings currents, (c) The efficiency (ignore the core losses but consider the feeder losses). 3- The magnetization characteristic of a DC generator running at 1000 rpm is shown below. This machine has armature resistance of 0.5 Ω and field resistance of 100 Ω. The machine is driven as a shunt DC generator by a diesel engine and is connected to a load of 5 Ω. The engine speed is adjustable. The generator is required to deliver 2kW to the load, calculate: (a) Output voltage of the DC machine. (b) Field current and armature current of the machine. (c) EMF of DC machine and speed of diesel generator. PwnHero.com