POWER SYSTEM ANALYSIS
SEM-VI, 2010
B.TECH EXAMINATION
UTTARAKHAND TECHNICAL UNIVERSITY
(UTU)
Time: 3 hours
Total
Marks:100
Attempt any four of
the following:
- One conductor of a three phase line is open. The
current flowing to the connected load through a line is 10A. With the
current in line a as reference and assuming that line c is open, find the
symmetrical components of the line currents.
- The line to ground voltages on the high voltage sides
of a step up transformer are 100 kV, 33 kV and 38 kV on phases a, b and c
respectively. The voltage of phase a leads that of phase b by 100o and
lags that of phase c by 176.5o. Determine analytically the
symmetrical components of voltage.
- The line currents in amperes in phase a, b and c
respectively is 500+j150, 100-j600 and -300+j600 referred to the same
reference vector. Find the symmetrical components of the currents.
- Three identical Y connected resistors from a load bank
with a three phase rating of 2300 V and 500 kVA. If the load bank has
applied voltages |Vab| = 1840 V, |Vbc| = 2760 V and |Vca| = 2300 V, find
the line voltages and currents in per unit into the load. Assume that the
neutral system and select a base of 2300 V, 500 kVA.
- A 25 MVA, 13.2 kV alternators with solidly grounded
neutral has a sub transient reactance of 0.25 pu. The negative and zero
sequence reactance are 0.35 and 0.1 pu. A single line to ground fault
occurs at the terminals of an unloaded alternator, determine the fault
current.
- Draw the zero sequence equivalent circuit of 3 phase transformer for various possible combinations.
