Electrical Engineering Department University of Santo Tomas Transformer Angular

# Electrical engineering department university of santo

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Electrical Engineering Department University of Santo Tomas Transformer Angular Displacement EE 523 – Power System Analysis and Design A B C a b c 1 2 3 4 5 6 V A V B V C V ab 1 2 3 4 V bc 5 6 V ca Vector Group: Yd1 a b c
Electrical Engineering Department University of Santo Tomas Transformer Angular Displacement EE 523 – Power System Analysis and Design A B C a c b 1 2 3 4 5 6 V A V B V C V ab 1 2 5 6 3 4 V bc V ca Vector Group: Yd11 a c
Electrical Engineering Department University of Santo Tomas EE 523 – Power System Analysis and Design INTRODUCTION TO FAULT STUDIES Rotating machineries will contribute fault current to the system. Alternators will continue to contribute at the duration of the fault. Motors (induction and synchronous) will have a decaying fault current at the duration of the fault
Electrical Engineering Department University of Santo Tomas EE 523 – Power System Analysis and Design SHORT CIRCUIT CURRENT CHARACTERISTIC
Electrical Engineering Department University of Santo Tomas EE 523 – Power System Analysis and Design SHORT CIRCUIT CURRENT CHARACTERISTIC Short Circuit Network Cycle ½ Cycle Network Used to calculate momentary SC current and protective devices at the ½ cycle after the fault Also referred as Sub-Transient Network 1. 5 to 4 Cycle Network Used to calculate the interrupting SC current and protective device duties 1.5-4 Cycle after the fault Also referred as Transient Network 30 Cycle Network Used to calculate the steady-state SC current
Electrical Engineering Department University of Santo Tomas EE 523 – Power System Analysis and Design TYPES OF FAULTS Shunt Fault: Unintentional Connection between phases or between phase to ground. Balanced/ Symmetrical Fault Three – phase fault Unbalanced/ Unsymmetrical Fault Singe Line – to – ground fault Double Line –to – ground fault Line – to – line fault Series Fault: Unintentional Opening of phase conductors Simultaneous Fault
Electrical Engineering Department University of Santo Tomas EE 523 – Power System Analysis and Design
Electrical Engineering Department University of Santo Tomas EE 523 – Power System Analysis and Design
Electrical Engineering Department University of Santo Tomas Fault Point EE 523 – Power System Analysis and Design
Electrical Engineering Department University of Santo Tomas Fault Point EE 523 – Power System Analysis and Design
Electrical Engineering Department University of Santo Tomas EE 523 – Power System Analysis and Design
Electrical Engineering Department University of Santo Tomas EE 523 – Power System Analysis and Design FAULT CALCULATION USING NETWORK REDUCTION (EQUIVALENT THEVENIN CIRCUIT AT FAULT POINT)
Electrical Engineering Department University of Santo Tomas EE 523 – Power System Analysis and Design Consider the three bus system shown below. Reduce the system into its equivalent sequence network when fault occurs at (a) bus 1, (b) bus 2, and (c) bus 3.
Electrical Engineering Department University of Santo Tomas EE 523 – Power System Analysis and Design Seatwork 15 MVA 13.8 kV x'' = 0.15 x 0 = 0.05 20MVA 13.8 kV - 115 kV x = 0.10 Z 1 = j500 ohms Z 0 = j800 ohms 15 MVA 115 kV - 13.2 kV x = 0.12 10 MVA 13.2 kV

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