1.a. Distinguish between progressive and retrogressive winding.

1.b. An 8 pole wave armature has 300 conductors and run at 800 rpm. Determine the useful flux /pole if the electromotive force generated on open circuit is 500V.

1.c. Distinguish between armature resistance control and field resistance control while controlling the speed of dc shunt motor?

1.d. Why is the starting current in dc motor very high? Describe the need of starter?

1.e. Define efficiency of dc machine and give its losses?

1.f. why is Hopkinson's test is called regenerative test?

1.g. the parameter of 2400/120V, 50hz Transformer are $R_{1}$ =0.1 ohms and $R_{2}$ = 0.035 ohms. Find $\mathrm{R}_{01}$ and $\mathrm{R}_{02}$

1.h. Will the Transformer draw any current from the source when secondary is open? Draw the phaser diagram for actual Transformer on no-load?

1.i. Define energy efficiency and voltage regulation of transformer?

1.j. Distinguish between auto transformer and ordinary 2-winding Transformer in brief?

2.a. What do you understand from the term armature reaction? Describe the role of compensating winding in a dc generator?

2.b. in a DC compound generator the armature, shunt-field winding and series field winding resistance are given by 0.6ohms, 150ohms, and 0.3ohms, respectively. The machine is connected to a load of 15 kW, 200V. Find the I) EMF generated ii) armature current and iii)power generated by armature when the machine is connected in long shunt mode.

3.a. Distinguish between DNA and MNA. Describe the role of interpoles in DC Generator.

3.b. Draw the load characteristics of d.c compound motor and shunt motor.

4 a. explain principal of operation of DC motor with a neat sketch.

4.b. A DC series motor is running with the speed of 100 RPM file tough a current of 30 A from A supply. If the load is changed such that the current drawn by the motor is increased to 70 A, calculate the speed of a motor on new load. The armature and series field winding resistance are 0.25ohms and 0.35ohms respectively. Assume the flux produced is proportional to the current. Take supply voltage as 260V.

5.a. why is dc series motor should never start on no-load? Draw and explain various characteristics of DC series motor.

5.b. list out the advantage of 4-point starter over 3-point starter? Draw and explain the 4-point starter along with protective devices.

6.a. Describe how you find the efficiency of DC motor using break test. What are its disadvantage?

6.b. Explain how the efficiency of DC Machine can be determined using hopkinson's test? Draw the appropriate diagram where ever necessary?

7.a. explain field's test performed on dc machines.

7.b. What are the advantage of swinburne's test over direct loading? Explain the test with relevant expressions.

8.a. "Core losses remain constant in the core irrespective of status of load across the secondary" justify your answer in brief. Draw necessary diagram.

8.b. A single phase transformer with a ratio of 440/110V take no-load current of 5A at 0.2 p.f lagging. If the secondary draws a current of 120A on load at 0.8 p.f lagging, calculate the primary current I1 in primary? Draw the phasor diagram.

9.a. Describe the effect of frequency and supply voltage on losses.

9.b. Obtain the equivalent circuit parameters of 220/400V, 50Hz, 1-phase transformer from the following test data. OC test: 200V, 0.7A, 70W. SC test: 15V, 10A, 85W(with LV short circuit).

10. The OC and SC test data of 4 KVA, 200/400V single phase transformer when supplying full load at 0.8 lagging p.f is given below. OC test: 200V, 0.8A, 70W(HV open circuit) SC test: 20V, 10V, 60W (L V short circuit) calculate efficiency at a) full load b)½ half load c) voltage regulation at full load.

11.a. Explain the working of single phase auto transformer with neat diagram? Drive an expression for saving of copper in it when compared to ordinary two winding transformer?

11.b. What is significance of Y-Y, Y-delta and Delta-Y, Delta-Delta connection in 3-phase transformers? TYPE_QUESTION_HERE