1.1 What is the per unit system (PU)?

• a) A ratio of actual value in any units to the base or reference value in the same units

• b) A ratio of the base or reference value in any units to the actual value in the same units.

• c) Ratio of the square of the actual value in any units to the square of base or the reference value in the same units

• d) All of these

1.2 Which among these is the major advantage of per unit computations?

• a. Per unit impedance of transformers is the same referred to either side of it.

• b. For simulating steady state and transient models in the computer this method is very useful.

• c. Manufactures usually specify the impedance of an apparatus in per unit system.

• d.all of these

1.3 Single line diagram does not represents:

• a) Star connection of transformer winding

• b) Delta connection of transformer winding

• c) Neutral wire of transmission lines

• d) Ratings of machines

1.4 What is the main purpose of reactance diagram?

• a) Load flow analysis

• b) Fault analysis

• c) Calculation of ratings of Alternators

• d) Calculation of ratings of Transformers

1.5 For n bus power system size of Y bus matrix is

• a) (n-1) × (n-1)

• b) (n-2)×(n-2)

• c) n×n

• d) (n-1)× (n-2)

1.6 What is the formula to calculate the (kV)_B on the HT section?

• a. (kV)_B on HT section * (HT voltage rating) / (LT voltage rating)

• b. (kV)_B on LT section * (HT voltage rating) / (LT voltage rating)

• c. (kV)_B on HT section * (LT voltage rating) / (HT voltage rating)

• d. (kV)_B on LT section * (LT voltage rating) / (HT voltage rating)

1.7 (2 marks) What will be the per unit impedance of a synchronous motor having a rating of 100 kVA, 13.2 kV and having a reactance of 75 Ω / ph?

• a. 0.043 pu

• b. 0.057 pu

• c. 0.036 pu

• d. 0.298 pu

1.8 (2 marks ) If sparsity of a 5 bus transmission line is 0.4. Find the number of transmission lines?

• a) 4

• b) 5

• c) 6

• d) 3

1.9 ( 2 marks) The per unit value of a 2 ohm resistor at 100 MVA and 10 kV base voltage is

• a. 4

• b. 6

• c. 2

• d. 2.3

2.1 Why are load flow studies carried out?

• a. To study of stability of the system

• b. For fault calculations

• c. For planning the power system

• d. All of these