Alternator Problems (3 phase and single phase AC Motor)

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Discussion Overview

The discussion revolves around solving various problems related to alternators, specifically focusing on three-phase and single-phase AC motors. The problems include calculating generated voltages, open circuit voltages, and power angles under different power factors, as well as determining armature conductors in a specific alternator configuration.

Discussion Character

  • Homework-related
  • Mathematical reasoning

Main Points Raised

  • One participant expresses a lack of understanding regarding the procedure to solve the alternator problems presented.
  • Another participant indicates they are also struggling with the same set of problems and expresses urgency for solutions.
  • A third participant introduces a different problem related to a three-phase, 10-pole alternator, asking for help in determining the number of armature conductors needed.
  • There is a request for guidance rather than direct answers, indicating a desire to understand the problem-solving process.

Areas of Agreement / Disagreement

Participants generally agree on the need for assistance with the homework problems, but there is no consensus on the solutions or methods to approach them, as multiple participants express confusion and urgency.

Contextual Notes

Participants have not provided specific assumptions or methodologies for solving the problems, and the discussion lacks detailed mathematical steps or definitions that could clarify the context of the problems.

Who May Find This Useful

Students studying electrical engineering or related fields, particularly those focusing on alternators and AC motor theory, may find this discussion relevant.

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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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