Podcast
Questions and Answers
Which factor is used to correct for the geometry of the coil in the back emf derivation?
Which factor is used to correct for the geometry of the coil in the back emf derivation?
What represents the total flux cut by each conductor during one revolution in the back emf formula?
What represents the total flux cut by each conductor during one revolution in the back emf formula?
What is the average emf induced per phase dependent on?
What is the average emf induced per phase dependent on?
How do you calculate the time taken to complete one revolution in relation to speed?
How do you calculate the time taken to complete one revolution in relation to speed?
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What is the relationship between the number of turns connected in series per phase (Tph) and the number of conductors (Zph)?
What is the relationship between the number of turns connected in series per phase (Tph) and the number of conductors (Zph)?
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Study Notes
Phasor Diagram for Load Condition (Under Excitation)
- Under load conditions with constant excitation, current increases, and power factor decreases.
- The angle φ (phase angle) increases.
Derivation for Back EMF (Eb)
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Variables:
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p= Number of poles -
∅= Flux per pole (in Webers) -
N= Speed in revolutions per minute -
f= Frequency in Hertz (Hz) -
Z<sub>ph</sub>= Number of conductors connected in series per phase -
T<sub>ph</sub>= Number of turns connected in series per phase -
K<sub>c</sub>= Coil span factor -
K<sub>d</sub>= Distribution factor
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Flux cutting: Each conductor cuts flux during one revolution.
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Time for one revolution: Time taken for one revolution = 60/N seconds
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Average EMF induced per conductor: (ΦpNx60)/60
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Average EMF induced per phase: (ΦpNx2Zph)/60
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Where N is speed.
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Description
Test your understanding of phasor diagrams under load conditions and the derivation of back EMF. This quiz covers key concepts such as phase angle changes and variables affecting electromagnetic forces in electrical engineering. Explore how these factors influence power systems and electrical machinery.
