Questions and Answers
Calculate the e.m.f. magnitude for a star connection with coils short-chorded by two slot pitches in the given generator.
The magnitude of the e.m.f. is 210 V.
What is the frequency of the e.m.f. generated by the synchronous generator with 4 poles running at 1500 r.p.m.?
The frequency is 50 Hz.
What is the total number of armature conductors in the synchronous generator, and how are they arranged?
The total number of armature conductors is 720, accommodated in 72 slots.
If the flux per pole is 0.035 Wb, how does it affect the generated e.m.f. in the synchronous generator?
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Explain why a star connection is used in the generator and its effect on the voltage output.
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Match the following components of a generator with their respective descriptions:
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Match the operational parameters of a generator with their respective values:
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Match the type of generator connection with its characteristic:
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Match the calculation method with the corresponding generator output aspect:
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Match the electrical terms with their definitions:
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Study Notes
Frequency of the E.M.F.
- A 3-phase synchronous generator has 4 poles.
- The generator operates at a speed of 1500 revolutions per minute (r.p.m.).
- The frequency is calculated using the formula:
-
Frequency (f) = (P × N) / 120*
where P is the number of poles and N is the speed in r.p.m. - Substituting the values:
- f = (4 × 1500) / 120 = 50 Hz*
- The frequency of the generated e.m.f is 50 Hz.
Magnitude of E.M.F.
- The total number of armature conductors is 720.
- Armature conductors are distributed across 72 slots.
- Each pole contributes to e.m.f generation due to the magnetic flux linked to the conductors.
- The magnetic flux per pole is 0.035 Weber (Wb).
- In a star connection with coils short-chorded by two slot pitches, the e.m.f can be estimated using the formula:
-
E = 4.44 × f × Φ × T*
where E is the e.m.f, Φ is the flux per pole, and T is the number of turns per phase. - The number of turns per phase (T) can be calculated from the total conductors divided by the number of phases (3):
- T = 720 / 3 = 240 turns per phase*
- Therefore, substituting into the e.m.f formula (assuming 2/3 of the flux contributes due to short chording), the formula becomes:
- E = 4.44 × 50 × (0.035 × (2/3)) × 240*
- The final calculated magnitude of the e.m.f for the generator will be obtained after evaluating the above expression.
Frequency of the E.M.F.
- A 3-phase synchronous generator has 4 poles.
- The generator operates at a speed of 1500 revolutions per minute (r.p.m.).
- The frequency is calculated using the formula:
-
Frequency (f) = (P × N) / 120*
where P is the number of poles and N is the speed in r.p.m. - Substituting the values:
- f = (4 × 1500) / 120 = 50 Hz*
- The frequency of the generated e.m.f is 50 Hz.
Magnitude of E.M.F.
- The total number of armature conductors is 720.
- Armature conductors are distributed across 72 slots.
- Each pole contributes to e.m.f generation due to the magnetic flux linked to the conductors.
- The magnetic flux per pole is 0.035 Weber (Wb).
- In a star connection with coils short-chorded by two slot pitches, the e.m.f can be estimated using the formula:
-
E = 4.44 × f × Φ × T*
where E is the e.m.f, Φ is the flux per pole, and T is the number of turns per phase. - The number of turns per phase (T) can be calculated from the total conductors divided by the number of phases (3):
- T = 720 / 3 = 240 turns per phase*
- Therefore, substituting into the e.m.f formula (assuming 2/3 of the flux contributes due to short chording), the formula becomes:
- E = 4.44 × 50 × (0.035 × (2/3)) × 240*
- The final calculated magnitude of the e.m.f for the generator will be obtained after evaluating the above expression.
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Description
Test your knowledge on the operation and calculations of a 3-phase synchronous generator. This quiz covers the determination of frequency and e.m.f in a star-connected system with specific parameters. Ideal for electrical engineering students and professionals.
