Transformers

Transformer

A magnetic device used to step AC voltages and currents up or down.

Transformer Core Function

High-permeability core confines magnetic flux and reduces reluctance.

Changing primary current produces changing magnetic flux that induces secondary voltage (Faraday’s Law).

Operating Principle of Transformers

Because electromagnetic induction requires changing magnetic flux

Why Transformers Require AC

Vs/Vp = Ns/Np

Voltage–Turns Relationship

Is/Ip = Np/Ns

Current–Turns Relationship (Ideal Source)

Pp = Ps = VpIp = VsIs

Ideal Power Equality

Center-Tapped Transformer

A transformer whose secondary winding has three terminals, with the middle terminal (center tap) often connected to ground.

Center Tap Grounding Effect

Grounding the center tap makes the two secondary voltages equal in magnitude but opposite in sign

V_sec1 = -V_sec2

Secondary Voltages (Center-Tapped); when one is positive, the other is negative

Vprim/Vsec,total = Nprim/Nsec,total

Turns Ratio (Center-Tapped Transformer)

Vp,sec = (Vp,prim)/(2N)

Peak Secondary Voltage (Each Half). Each half of the secondary has peak voltage