Magnetism Question

There is no way to get any DC out of your array. The only thing you can do is increase the DC and smoke up the secondary. Transformers don't work with real smooth DC. Only DC pulses stand a chance.

Thanks,but the secondary DC amp is limited to 1 amp DC via a limiting resistor , so no heat is generated.

So? It still won't work.

The steady DC does not change, and therefore induces no current in the other winding. (Except at the moments when it is connected and disconnected.)

Thanks, but according to Amper's law for magnetism the sum of mmf's must be zero(NI=NI),so 1 amp DC must flow through the primary.

Codswallop.

Dear guest,

Transformers require there to be fluctuation in the current/voltage applied so that there is change in the magnetic flux in the transformer core to then induce a current/voltage in the other winding.

Applying DC to a transformer causes as steady state current and a steady state flux which will not induce a voltage or current in the other winding.

Thus on the primary, you will only see the result of the initial mains ac that you have already connected.

There are other complex items that might need to be considered if both excitations were AC relating to phase, frequency and flux density in the transformer iron, but they are not of consequence in the example you have described.

This is one reason why 1:1 transformers are used. They can provide DC isolation while allowing the AC power to pass.

Tornado, look! A fence post!

Since you are passing 1 amp DC through secondary it will be not reflected on primary in terms of voltage, But if you measure the output on the secondary coil with CRO you find AC output that is riding on DC voltage, that is due to DC drop According to ohms law.

If you measure the AC current on primary coil you will observe an upward drift in it after passing that 1 AMP or more DC in secondary, This happen due to magnetic saturation of core. And as the saturation is increased by passing more and more current in secondary Its AC output voltage will go down.

So simply speaking, passing DC in secondary will increase primary AC current and will decrease secondary AC voltage.

Yes I'm agree with you , but why the relation (NI)p=(NI)s is not valid in this case ?

A transformer will not transform DC voltage under any circumstance. When you connect a transformer primary to a DC source the transformer will attempt to do what you expect, but as the core saturates you will get no more out. So the only output you can expect is a single DC pulse. As the core saturates the transformer primary looks to the main like a short circuit. If your main is DC you will need to use something other than a transformer. If your main is AC, the output of your transformer will be AC.