5.a. A characteristic common to most steam-turbine alternators is A. belt drive. B. salient-pole rotor construction. C. gear drive. D. cylindrical rotor construction. 5.b. The stator core of an alternator is safeguarded against high short-circuit current by a device called a A. surge capacitor. B. lightning arrester. C. differential protector. D. temperature detector.

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)

6. The relation between the field current and the armature current in an alternator with the armature short-circuited can be shown byA. a rated-current 80% pf saturation curve.B. a synchronous impedance curve.C. an open-circuit saturation curve.D. a zero-power-factor regulation curve.

Find the value:

The ac armature winding of an alternator is   A. Always Star connected.   B. Always delta connected