B-State the steps to obtain zero power factor characteristic of synchronous generator? A- i- ii- iii- For synchronous machines :- Define with plot the V-curves of synchronous motor? State the equation of power developed by three phase salient pole synchronous generator and draw the power angle characteristic for it? Discuss the hunting of synchronous motor?

4. For a general DC generator, we aim to achieve constant output voltage at different rotating speeds. (1) List two factors influencing the output voltage for a given DC generator. (2) How does the change of the load (assuming the load is the current flowing though the resistor) will impact on the generated voltage for (a) separately excited DC generator, (b) Shunt DC generator, and (c) cumulative compound DC generator?

Please solve this problem step by step and illustrate your answer properly. Write your answer in a piece of paper please. Box the final answer.

2.A 10-MVA 4.6-kV 60-Hz 6-pole three phase synchronous generator has armature resistance of 2 ohms and synchronous reactance of 6 ohms. It is operated at rated frequency to supply rated load at rated voltage at a power factor of 0.9 lagging. Assume mechanical losses are negligible. a.Determine the magnitude of the line-to-line excitation voltage. b.Determine the input power for the generator, in MW. (Please compute in W or kW before converting to MW)

A three-phase, 1 MVA, 2.3 kV, 60 Hz, star-connected, salient pole synchronous generator has the d- and q-axis synchronous reactances are 1.1 and 0.8 Q respectively. Its armature has a resistance of 0.15 §. The machine is operating at full load at a power factor of 0.8 lagging. Determine the excitation voltage Ę and draw the generator phasor diagram using actual values.

A 300 KW and 600 V Long shunt compound DC generator has shunt field resistance = 100 2 armature resistance = 0.05 Q series field resistance = 0.02 Q commutating field winding resistance = 0.015 N connected in series with armature winding and diverter resistance = 0.03 N connected in parallel with commutating field. When the generator is delivering half full load, calculate power generated by the armature.

3

With the aid of diagrams describe the basic topology of a wound field 3 phase synchronous generator and outline the relationship between the excitation voltage and rotor current. Q2 (a) (b) Outline with the aid of a suitable diagram the necessary power conversion stages required to interface a small permanent magnet (PM) generator to a stand alone DC system. A star connected 3 phase wound field synchronous generator with a synchronous reactance of 20 N is connected to a 6.6 kV (phase voltage) grid and supplies 1.5 MW at 0.95 lagging power factor at its terminals. Calculate the phase current and resultant voltage across the synchronous reactance (Vxs), and from a scaled phasor diagram graphically determine the required excitation voltage (Eph) and load angle (8). (c) The load is now increased to 3 MW with the Excitation Voltage kept constant. Using the phasor diagram drawn in part (c) graphically determine the resultant phase current, power factor and load angle. (d)

hele Ish 0.05 50 A To R 30 A

Single phase induction motor performance characteristics 6. Explain double revolving field theory.