CL wadhwa bits solutions (140-144)

Lesson 5 of 26 • 28 upvotes • 15:00mins

Anvesh Sameer

140. The inertia constant of two groups of machines which do not swing together are M1 and M2 such that M1 > M2. It is proposed to add some inertia to one of the two groups of machines for improving the transient stability of the system. It should be added to: (a) M1 (b) M2 (c) It does not matter whether to add to M1 or M2. 141. Tick out the correct one: (a) Higher the SCR of a machine the heavier is its rotor (b) Higher the SCR of a machine the lighter is its rotor (c) The SCR and size of the rotor are not at all related. 142. A 100 V/10 V, 50 VA transformer is converted to 100 V/110 V auto transformer, the rating of the auto transformer is: (a) 550 VA (b) 500 VA (c) 110 VA (d) 100 VA. 143. A 100 KVA transformer has maximum efficiency of 98% when operating at half full load. Its full load losses are: (a) Cu = 2.04 kW and Iron loss = 0.51 kW (b) Cu = 4.08 kW and Iron loss = 1.02 kW (c) Cu = 3.0 kW and Iron loss = 0.75 kW (d) None of the above. 144. A voltmeter gives 120 oscillations per minute when connected to the rotor. The stator frequency is 50 Hz. The slip of the motor is: (a) 2% (b) 4% (c) 5% (d) 2.5%.