Characteristics Of A Transformer

3.5 Transformer:-

Definition: - The transformer is a static electro-magnetic device that transforms one alternating voltage (current) into another voltage (current). However, power remains the same during the transformation. Transformers play a major role in the transmission and distribution of ac power.

Principle: - Transformer works on the principle of mutual induction. A transformer consists of laminated magnetic core forming the magnetic frame. Primary and secondary coils are wound upon the two cores of the magnetic frame, linked by the common magnetic flux. When an alternating voltage is applied across the primary coil, a current flows in the primary coil producing magnetic flux in the transformer core. This flux induces

If the turns of the coil are oriented perpendicular to the magnetic field lines, the flux is the product of the magnetic flux density B and the area A through which it cuts. The area is constant, being equal to the cross-sectional area of the transformer core, where the magnetic field varies with time according to the excitation of the primary. Since the same magnetic flux passes through both the primary and secondary coils in an ideal transformer, the instantaneous voltage across the primary winding equals. Taking the ratio of the two equations for Vs and VP gives the basic equation for step up aur step down the voltage.

Ideal power equation- The ideal transformer as circuit elements-

If the secondary coils are attached to a load that allows current to flow, electrical power is transmitted from the primary circuit to the secondary circuit. Ideally, the transformer is perfectly efficient; all the incoming energy is transformed from the primary circuit to the magnetic and into the secondary circuit. If this condition is met, the incoming electrical power must equal the outgoing power.

Pincoming = IpVp = Poutgoing = IsVs

Giving the ideal transformer