How does a power transformer even work?

Question

I'm wondering how a transformer even >> works << against 120 VAC power. Say like in a circuit that drops 120 VAC to 12 VAC and then goes thru a DC rectifier. As I understand it, a transformer is composed of several loops of wire on the primary (input) coil that generates current running thru the secondary (output) coil.

But if you've ever tried crossing the wires on the 120 VAC wall outlet, BAM! Big sparks, and instant blown circuit breaker. Isn't there effectively a near short-circuit condition at the 120 VAC input to the transformer? So how does it even work?

veeyesvee · Accepted Answer

have you heard of inductance? Do you know what the core does for this inductance? Does it matter if the core is replaced by a wooden former?? Read , Read, and more of it, till the whole thing starts making sense. getting an answer here or there is not end of this learning. Do not connect a loop of wire and create BANGs.
the transformer with two separate winding works on the principle of interaction between magnetic field created by the primary and its effect on secondary. read more from Kuphaldt: lessons in electrical engg, downloadable from DISCOVER CIRCUITS

Morningfox · Answer

No, there is not a short-circuit.  The wire coils have an impedance to the electric flow, because the current is AC.  Any coil will have an impedance to AC current.  Plus, there is a magnetic field that flows between the primary and secondary coils, which couples the two coils together.  The transformer is designed to make this coupling as strong as possible.  This makes the secondary circuit part of the primary circuit.  Any resistance or impedance in the secondary circuit is felt in the primary circuit.

When you cross the wires in a wall outlet, there is no coil (or very little coil), no secondary circuit, and hardly any resistance.

Trending News

How does a power transformer even work?

2 Answers