what will happen if the AC current in the transformer is replaced by a DC current?

Question

If the AC supply is replaced by a DC supply, there will be absence of alternating flux,so what will be the behaviour of the transformer?

Answer 1

Both the primary side and secondary sides of the transformer will become (effectively) useless inductive loads.

Without some variation of current through the primary side, no magnetic flux changes occur, and no change will be seen across the secondary side. It'll draw more current than it did as a load under AC conditions.

One way to get DC to provide something on the secondary is to switch it on and off to bring up and collapse the field (picture a coil on a car -- it operates on switched DC instead of AC).

Answer 2

When the DC supply is first turned on there will be a momentary burst of flux (from zero to full scale) that will result in a corresponding short burst of output voltage from the secondary. After that nothing in the secondary because of that absence of alternating flux. In addition if the DC resistance is not adequate for the primary DC input voltage the primary winding might be overheated and burn out.

Answer 3

"is there any way i can charge the same batteries by recycling its current using a 220v to 24 v converter" No, because running a 220v to 24v converter will just act as an additional load on the inverter anyway. This is straying into perpetual motion territory and that never seems to work :-) "f i use external 1 horse power 220v ac motor coupled with a truck 24v alternator and than feed back this 24 volts back to batteries" What is turning the motor? If the answer is the inverter then again this wont work because all the power turning the alternater came from the batteries anyway. You need to get the idea that it isn't just about volts or things turning round, its about power and energy. An alternator doesn't just spin round freely and make power from out of the air, turning it round is hard work and requires energy, the very energy that ends up in the battery. If you get an alternater or a dynamo and spin it with no electrical load connected it will turn freely but the moment you connect it to a load it immediately has a mechanical resistance to moving. Likewise with the converter, it will consume power in order to pass power on. Apart from more amp-hour batteries you could run a generator (requiring fuel!!) at the same time and treat that like a car alternater to put some charge back in the batteries as they are used.

Answer 4

If the current draw is enough, you'll burn the primary windings of the transformer out. Nothing will come out of the secondary due to the voltage being induced on an inductor being due to the rate of change of current ( V= L di/dt), with DC di/dt is ZERO, hence no voltage.

In addition, you will flux walk the transformer up it's hysteresis curve, but since the transformer isn't being used properly, that doesn't matter.

Essentially the transformer will look close to a dead short to the supply.

Answer 5

The primary coil will probably reach overcurrent. (A short circuit) Additionally, the magnetic field will possibly have enough strength to deform the components of the transformer.

I once hooked AC 120V to a 24V DC door holder magnet and the AC current was still lower than the designed DC current.

Answer 6

There will be no current coming out of the secondary because you need a changing madnetic field between the windings for it to work. Also, since the inductive reactance doesn't work at DC the primary will draw high current.

Answer 7

since the primary coil wouldnt have magnetic field then the transformer wouldnt be working . The transformer are only for AC currents.

Answer 8

http://www.newton.dep.anl.gov/askasci/engine98.htm