What happens if you supply 220V DC to the transformer

Supplying 220V DC to a transformer designed for AC input can cause serious problems, including potential damage or failure.

Here’s why:

1. Transformers Work on AC, Not DC

   - Transformers rely on changing magnetic fields (Faraday’s Law of Induction) to transfer energy from the primary to the secondary winding.

   - DC voltage does not change over time, so it cannot create a varying magnetic field.

   - Without a changing magnetic field, no voltage is induced in the secondary winding.

2. Consequences of Applying DC to a Transformer

   - High Current Draw (Almost Like a Short Circuit):

     - The primary winding of a transformer has very low DC resistance (only wire resistance).

     - Applying DC causes a large current to flow (since there’s no inductive reactance to limit it).

   - Overheating & Burnout:

     - The excessive current can overheat the windings, damaging insulation and possibly melting wires.

   - Core Saturation:

     - The transformer core can become magnetically saturated, further increasing current and heat.

   - Possible Smoke/Fire Risk:

     - If the transformer is not protected (e.g., by a fuse), it may burn out, smoke, or even catch fire.

3. Will the Secondary Output Any Voltage?

   - No, because DC does not create a changing magnetic flux.

   - The only voltage you might see is a brief spike when connecting/disconnecting DC, but this is not useful and can be dangerous.

4. Exceptions (Special Cases)

   - Some pulse transformers or flyback converters can handle DC pulses, but standard AC transformers cannot.

   - If you need to step up/down DC, use a DC-DC converter instead.

Conclusion

⚠️ Never apply DC to an AC transformer—it will likely overheat, burn out, or fail catastrophically. Always use the correct input voltage type (AC for traditional transformers).  

If you need to convert DC, consider using:

- Buck/Boost Converters (for DC-DC conversion)

- Inverters (to convert DC to AC first)