1
GATE EE 2009
+2
-0.6
For the $${Y_{bus}}$$ matrix of a $$4$$-bus system given in per unit, the buses having shunt elements are $${Y_{BUS}} = j\left[ {\matrix{ { - 5} & 2 & {2.5} & 0 \cr 2 & { - 10} & {2.5} & 4 \cr {2.5} & {2.5} & { - 9} & 4 \cr 0 & 4 & 4 & { - 8} \cr } } \right]$$A $$3$$ and $$4$$ B $$2$$ and $$3$$ C $$1$$ and $$2$$ D $$1,2$$ and $$4$$ 2 GATE EE 2006 MCQ (Single Correct Answer) +2 -0.6 The Gauss Seidel load flow method has following disadvantages. Tick the incorrect student. A Unreliable convergence B Slow convergence C Choice of slack bus effects convergence D A good initial guess for voltages is essential for convergence 3 GATE EE 2006 MCQ (Single Correct Answer) +2 -0.6 For a power system the admittance and impedance matrices for the fault studies are as follows. \eqalign{ & {Y_{bus}} = \left[ {\matrix{ { - j8.75} & {j1.25} & {j2.50} \cr {j1.25} & { - j6.25} & {j2.50} \cr {j2.50} & {j2.50} & { - j5.00} \cr } } \right] \cr & {Z_{bus}} = \left[ {\matrix{ {j0.16} & {j0.08} & {j0.12} \cr {j0.08} & {j0.24} & {j0.16} \cr {j0.12} & {j0.16} & {j0.34} \cr } } \right] \cr}

The pre-fault voltages are $$1.0$$ $$p.u.$$ at all the buses. The system was unloaded prior to the fault. A solid $$3$$ phase fault takes place at bus $$2.$$

The post fault voltages at buses $$1$$ and $$3$$ in per unit respectively are

A
$$0.24,0.63$$
B
$$0.31, 0.76$$
C
$$0.33, 0.67$$
D
$$0.67, 0.33$$
4
GATE EE 2006
+2
-0.6
For a power system the admittance and impedance matrices for the fault studies are as follows. \eqalign{ & {Y_{bus}} = \left[ {\matrix{ { - j8.75} & {j1.25} & {j2.50} \cr {j1.25} & { - j6.25} & {j2.50} \cr {j2.50} & {j2.50} & { - j5.00} \cr } } \right] \cr & {Z_{bus}} = \left[ {\matrix{ {j0.16} & {j0.08} & {j0.12} \cr {j0.08} & {j0.24} & {j0.16} \cr {j0.12} & {j0.16} & {j0.34} \cr } } \right] \cr}\$

The pre-fault voltages are $$1.0$$ $$p.u.$$ at all the buses. The system was unloaded prior to the fault. A solid $$3$$ phase fault takes place at bus $$2.$$

The per unit fault feeds from generators connected to buses $$1$$ and $$2$$ respectively are

A
$$1.20, 2.51$$
B
$$1.55, 2.61$$
C
$$1.66, 2.50$$
D
$$5.00,2.50$$
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