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High frequency is suitable for small transformers with ferrite core, but that causes high impedance. Can we use that impedance to limit the current in a transformer of 1:1 ratio to 1 A without overheating or dissipation of energy?

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In a transformer, the inductance of each coil is measured as the inductance with the other coil forming an "open circuit."
When you short the secondary coil in a transformer, the inductance of the primary coil drops dramatically.

If I understand the intent of your question correctly, this is where your intended use of a "high impedance" (although it'd be correctly stated as "high reactance" or "high inductance") primary coil to limit overall transformer current flow will break down.
In order to limit the max. possible output current of your transformer to a certain value, the resistance (not reactance, just resistive losses) in the coils and the magnetic losses in the core+coupling between the two coils would have to be great enough to limit the current to that amount.
This would, unfortunately cause highly inefficient operation, high losses, and likely the overheating that you are wanting to avoid.

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  • \$\begingroup\$ How do airgaps alter the behavior? \$\endgroup\$ Apr 23 '17 at 22:44
  • \$\begingroup\$ @analogsystemsrf Honestly, I don't know much about the effets of airgaps in transformers yet. So far, the only reference I've seen to them in my research are a few references to airgaps being incorporated in the core material for flyback transformers, in order to add some reluctance. \$\endgroup\$ Apr 23 '17 at 23:06
  • \$\begingroup\$ @RobhercKV5ROB i am really confused now so its the inductance and not the impedance right? \$\endgroup\$
    – saad
    Apr 23 '17 at 23:47
  • \$\begingroup\$ @saad The impedance of a transformer is the combination of its inductive reactance at the frequency of opteration, electrical resistance of the wire used in the windings, and several parasitics (ferro-magnetic heating/deforming of the core, magnetic hysteresis, inter-winding capacitance, etc.). While a transformer with a high enough resistive & parasitic impedance can indeed limit max. output current (due to losses), ... \$\endgroup\$ Apr 24 '17 at 0:38
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    \$\begingroup\$ @saad Please don't take this the wrong way, but my personal policy is that anything worth researching/studying is worth researching in print. While YouTube videos are great for entertainment & for watching demonstrations of things you've been researching, I doubt many of us here will agree to watch & comment on YouTube videos. Unfortunately, that often simply becomes a problem of debunking thousands (if not millions) of videos that are either negligently (or intentionally) spreading mis-information. If you can find a text-reference to what you're thinking, I'll happily read it & comment. \$\endgroup\$ Apr 24 '17 at 0:55
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Impedance does limit transformer current. This impedance comprises copper resistance which wastes power and leakage inductance which does not waste power. In most transformers this impedance is very low so the short circuit current is very high like say 20 times the load current meaning that the transformer would burn out under prolonged short circuit conditions. These orthodox transformers have reasonably good load regulation. Transformers with high impedance can be realized by using magnetic shunts can have current limiting properties that give a sagging VI curve. Microwave ovens and battery chargers use these transformers.

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