Alternator Problems (3 phase and single phase AC Motor)

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SUMMARY

This discussion focuses on solving electrical engineering problems related to alternators, specifically a 4MVA, 13.3kV, 60Hz, 3-phase delta-connected alternator and a 750kVA, 2300V delta-connected alternator. Key calculations include determining full-load generated voltage per phase at various power factors, calculating voltage regulation at 0.8 power factor lagging, and deriving open circuit voltage for a star-connected alternator. The participants express a need for procedural guidance rather than direct answers, emphasizing the importance of understanding the underlying concepts.

PREREQUISITES
  • Understanding of 3-phase alternator operation
  • Knowledge of power factor and its impact on voltage
  • Familiarity with electrical circuit testing methods (open and short circuit tests)
  • Basic principles of synchronous machines and their calculations
NEXT STEPS
  • Study the calculation of full-load generated voltage in alternators
  • Learn about voltage regulation in alternators and its significance
  • Explore the methodology for performing open and short circuit tests on alternators
  • Investigate the effects of power factor on alternator performance
USEFUL FOR

Electrical engineering students, professionals working with alternators, and anyone involved in the design or analysis of electrical power systems.

asteg123
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Homework Statement



1. A 4MVA, 13.3kV, 60Hz, 3 phase, delta-connected alternator has an effective resistance of 5.2 ohm/phase and a combined armature reactance of 54 ohm/phase. Determine the full-load generated voltage per phase, a. At unity pf, b. at 0.8 pf lagging, and at 0.866 leading pf.

2. A 750kVA, 2300V, delta-connected, 3-phase alternator has had open and short circuit tests performed and the following date were obtained:

Short Circuit test

Field current = 31.5A
Line current = rated

Open-circuit test

Field-current = 31.5A
Line voltage=1050V

The dc resistance across the terminals was measured at 0.38 ohm. Calculate the V.R. at 0.8pf lagging.

3. Calculate the open circuit votlage of a 3phase, star-connected alternator, 4 pole, 60Hz, 120 slots with each slot having 6 conductors in two layers. The machine is running at 1800rpm with a flux per pole of 125 milliWeber. The coil span is 12.

4. A single phase alternator, 50kVA, 460V supplies the rated load at 0.88 pf lagging. The dc resistance across the terminals ais 0.5 ohm and the synchronous reactance is 2.5 ohm. Calculate the angle of the power.


Homework Equations





The Attempt at a Solution



I have completely no idea on how to solve these problems...

I don't need the direct answers, I just want you guys to help me solve it, more on the procedure of solving it. Suffice to say, i want you guys to guide me in solving these problems.
 
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you know, I'm also wondering how to solve this exact 4 questions..

are you my classmate or something?!

i hope someone solves this ASAP.. coz I'm really desperate.. i need the solutions by tom.. :cry:
 
1. Find the number of armature conductors in series per phase required for 3 phase, 10 pole alternator when driven at a speed of 600 RPM. Armature has 90 slots and armature winding is star connected to give induced emf of 11KV between lines. Assume flux per pole as 16 mwb?
 
hey guys please help me in above problem...
 

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