What will happen to a charge superconducting electromagnet core in a generator? - Page 1
Forum section: electronics / general

author: BrianHG
author_rank: Super Contributor
timestamp: September 12, 2017, 05:55:35 am
content: I'm having trouble with this hypothetical situation:Say I replaced the permanent magnets in a permanent magnet generator with a charged superconducting coil as a new DC powered electromagnet. The idea is I only charge the superconducting coil creating the new electromagnet once before installing it in the generator so it acts as a permanent magnet. Everything else about the generator is normal conventional metal and copper wire winding.If I spin this generator and draw power from the regular copper wire, will there be any effect in the charge of the superconducting coil electric magnet core?Or will the superconducting coil magnet core be forever a magnet until I break that super-conductor loop?

author: helius
author_rank: Super Contributor
timestamp: September 12, 2017, 07:15:24 am
content: The situation is no different from a generator using a conventional copper field coil. The field coil has the same impedance no matter if the generator is spinning or not. In the case of the superconducting magnet, its resistance is zero, so it will continue carrying the same current (actually there is a possibility of losses as vortices of magnetic flux creep around). The rotor does produce an opposite magnetic field as it turns, but magnetic fields do not penetrate into superconductors so that doesn't have any effect on it.

author: BrianHG
author_rank: Super Contributor
timestamp: September 12, 2017, 07:20:21 am
content: @helius, so what you are saying is that the magnetic field in the superconductor created by the flowing current, is completely immune by the modulating/reflecting magnetic load of the outer copper coils as you spin it. This drag/flux created by the loaded normal copper wire wont have any effect on the current in the superconductor. It is immune from any such outside events.

author: helius
author_rank: Super Contributor
timestamp: September 12, 2017, 07:27:19 am
content: Yes, as long as it remains superconducting. If the field it is in gets too strong it can suddenly revert to normal and make a very big bang, though.

author: rs20
author_rank: Super Contributor
timestamp: September 12, 2017, 07:35:58 am
content: As I understand it, what the superconductor experiences is equivalent to being just a stationary block of superconductor, with permanent magnets being moved and dragged all around the place. While these magnets can induce eddy currents in the superconductor as the magnet approaches, that extra current loop just sits there and if you remove the magnet, the process reverses and you end up in exactly the same state that you started; no losses to speak of.It's quite easy to understand in the context of a block of superconductor with a permanent magnet being lowered to its surface and raised again -- and I see no particular reason why any other sort of motion would behave differently.

author: BrianHG
author_rank: Super Contributor
timestamp: September 12, 2017, 08:17:30 am
content: Quote from: rs20 on September 12, 2017, 07:35:58 amI am replacing the original magnets with a DC charged super-conductor creating an electromagnet. My original premise for thinking that spinning this superconductor would weaken it's charge since the load on the copper coils would fight against the superconductor, not creating a perfect mirror since the regular copper coils exhibit some loss. Sort of like fighting against a reverse polarity magnet which just weakens just so slowing down the current in the superconductor at each polarity change by just a little less each time as charge decays. But, now, there are 2 views against me here and I'm beginning to believe the superconductor magnet's charge cant be changed by any external magnetic load.