Unwanted Heating from Electromagnetic Induction 1

[brianFWM]

Hi,
I have a situation.
Added a large medium voltage (12.5 kV) switch enclosure to a generator circuit. Only available siting was between two large current-limiting reactors. The switch enclosure sits approx. 6 ft. from one reactor, approx. 12 ft. from the other. Before siting we considered that there may be some induction in the switch enclosure, but went ahead with the siting.

Now that the switch is in service, there is obvious inductive heating going on in the switch enclosure. It is present all over the enclosure, but is especially concentrated in two places (possibly where most of the bus work is inside the enclosure. This is a real problem when combined with solar temp. gain and high ambient temperatures.

What steps can I take to reduce the inductive heating in this switch enclosure (other than moving it)?

Are there barrier materials that will cut down the EM induction?

Note: The reactors are enclosed in vented metal enclosures, with steel side panels that are insulated to prevent large eddy currents.

Thanks,
Brian

 

[KB3HHC]

Aluminum panel enclosures would help. Although there are still induced currents, the nonmagnetic nature of the material greatly reduces the heating from hysteresis. Not sure how could quantify this.

 

[Skogsgurra]

You may also reduce the eddy currents by making slots in the material. That will increase reistance and probably reduce eddy currents. The most effective way is to make the slots radially, emanating from the spot where the heat is concentrated. You can then, if needed, cover the slots with an insulating sheet material.

Gunnar Englund

http://www.gke.org