Q4Basic Electrical Engineering

Question

Q.4. Give the emf equation of a transformer and define each term.

Answer 1

The Root Mean Square (RMS) value of the induced Electromotive Force (EMF) in any winding of a transformer is given by the fundamental equation:

E = 4.44 \cdot f \cdot ϕ_{m} \cdot N

E: The RMS value of the induced EMF in the winding (measured in Volts).
4.44: A constant derived from the form factor of a sinusoidal wave ( $1.11 \times 4$ ).
f: The frequency of the alternating current supply (measured in Hertz, Hz).
\phi_m: The maximum magnetic flux in the transformer core (measured in Webers, Wb). Note: $ϕ_{m} = B_{m} \times A$ , where $B_{m}$ is maximum flux density and $A$ is core area.
N: The total number of turns in the respective winding (primary $N_{1}$ or secondary $N_{2}$ ).

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