Magnetic Clearances Around Reactor Banks 4

[patrick7]

Question?

Manufactures of air core reactors show magnetic clearance boundry lines for their reactors. Some show a boundry for metal not forming a continous loop and one for those forming continous loops. Some also show the boundry lines as they extend underground. I have seen designs where the reactors are situated within each others magnetic boundry while others are not within the boundry lines.

My question is how do you handle these requirement?

 

[dpc]

If this is a high ac current application, you do have to be concerned about induced current in steel rebar in the foundation. You can use fiberglass rebar, or you can make sure that the rebar is not allowed to form a continuous loop. The crossing points should be insulated from each other. We have run into this restriction for very high current transformer rectifiers.

If the reactors are air-core, the mutual coupling between the reactors shouldn't cause any major heating effect, but it might have some impact on the reactance, although I wouldn't expect it to be major. But I'm basically guessing about that.

 

[patrick7]

sorry about the lack of info to start with
these are air core reactors and they are operating at 17kV and have a fault duty of 65KA.

 

[dpc]

It's not the fault duty as much as the continuous current. The manufacturer should provide installation recommendations, including any "iron-free" zones they think are necessary.

 

[patrick7]

Great, thank you for the information

 

[scottf]

Patrick7, I work for a company that sell air-core reactors, so I understand your question.

On the reactor drawing, there should be a dimension of the minim distance between center-lines of adjacent reactors. It is very important to maintain this clearance. Heating can be a concetn, but more importantly the mechanical forces that the reactor sees during a fault is affected by this clearance.

Certainly for a reactor with a rating of 65 kA, this clearance is critical. The reactor and the insulator configuration has been designed with this clearance in mind. Putting the reactors too close together could cause the reactors to fail mechanically and electrically during a fault (which of course is when you need them the most!).

 

[patrick7]

scottf
thank you very much that information is very helpful.

 

[cuky2000]

I hope the enclose information could help.