Assignment

Assignment No. 1

Course : AC Machines | Course Code: EE 2223 |

Instructor: Prof. Riaz Ahmad Rana | Sections: F09 – A, D & G |

Assignment Date: March 15, 2011 | Submission Date: March 31, 2011 |

Question # 1

A 3-phase, 2000KVA, 11 KV, star-connected alternator has armature resistance of 1 Ω/phase and a synchronous reactance of 10 Ω/phase. The speed and the excitation current remain unchanged.

Find the percentage change in terminal voltage when the rated output of 2000 KVA is switched on at :

(1) 0.8 PF Lagging Load?

(2) Unity PF Load?

(3) 0.8 PF Leading Load?

(4) EA from equivalent circuit?

Problem # 2

A 3-phase, 2300 V, 1000 KVA, 50 Hz, star connected synchronous generator has the following parameters:

p.f.= 0.8 Lagging, Poles = 2, Ra / phase = 0.15 Ω, Xs / phase = 1.1 Ω, PF&W = 24 KW, PCORE = 18 KW, VF = 200 V, IF = 10 A, R F = 20 – 200 Ω

a) Internal generated voltage of this generator at rated current?

b) Torque angle?

c) Generator’s prime mover output?

d) Generator efficiency?

e) % age Voltage Regulation?

f) Approximate power of generator?

g) Static Stability Limit?

h) Phasor Diagrams?

Problem # 3

A 3-phase, 2300 V, 1000 KVA, 50 Hz, star connected synchronous generator has the following parameters:

p.f.= 1, Poles = 2, Ra / phase = 0.15 Ω, Xs / phase = 1.1 Ω, PF&W = 24 KW, PCORE = 18 KW,

VF = 200 V, IF = 10 A, R F = 20 – 200 Ω

a) Internal generated voltage of this generator at rated current?

b) Torque angle?

c) Generator’s prime mover output?

d) Generator efficiency?

e) % age Voltage Regulation?

f) Approximate power of generator?

g) Static Stability Limit?

h) Phasor Diagrams?

Problem # 4

A 3-phase, 2300 V, 1000 KVA, 50 Hz, star connected synchronous generator has the following parameters:

p.f.= 0.8 Leading, Poles = 2, Ra / phase = 0.15 Ω, Xs / phase = 1.1 Ω, PF&W = 24 KW, PCORE = 18 KW, VF = 200 V, IF = 10 A, R F = 20...