Eddy current

[vinod]

How eddy current is created in an electrical circuit?
How can we prevent accumulation of eddy current in a single core cable gland plate?
I observed in a 480v MCC that, the gland plate was separated to avoid eddy current. Find attached photograph.
My question is, how can we prevent the eddy current by separating the gland plate?

 

[templdl]

The gap that was created breaks the circular current path around the conductor. When that current path is broken it reduces the heat that can be generated around the conductor where the conuctor passes through the enclosure.
Also, I did see a note regarding the loss of strength when this is done. I agree that this would decrease the strength. But is this really an issue?

 

[dicklaxt]

I have seen many many installations of this setup without the separation over the years and it never was a problem to my knowledge,is this something noticed in recent years that is now considered a problem?Aha! Just realized you are speaking of single conductor cables I'll betcha

dick

 

[nakulak]

http://www.tycothermal.com/assets/Americas/English/Document/Miscellaneous/1831/AppendixF_H57615_Copper_Sh_Currents_0909web.pdf

 

[vinod]

Is this raleted to anything about nonmagnetic and magnetic metal gland plate? Do we need to split the plate for non magnetic metal gland plate?

 

[don_resqcapt19]

...Do we need to split the plate for non magnetic metal gland plate?

No. The problem only occurs with a single conductor that is encircled by ferrous metal.

 

[winnie]

At the most basic level, you will see induced current flow in the brass glands, but magnetic materials amplify the effect, and I suspect that the brass glands are not considered problematic.

Different code standards approach this issue differently; I believe that the US code requires slotting in any situation where you have isolated conductors like this (with the exception of old residential knob and tube), and that other codes only require slotting above a certain current level. I am sure that at high enough current levels those brass glands would become a problem as well...but I don't know what current level this would be.

-Jon

 

[LarryFine]

Eddy currents can be induced in non-ferrous metals, too. The aluminum rotor disc in a watt-hour meter is one example.

 

[CPorter]

Eddy currents

Eddy currents

Any conductor placed in a moving magnetic field will have eddy currents

 

[Jraef]

The most common way to prevent this of course is to not pass single conductors through separate penetrations in the first place! If you have 2 parallel runs of conductors for example, use 2 conduits with one conductor of each phase in the same conduit.

 

[nakulak]

The most common way to prevent this of course is to not pass single conductors through separate penetrations in the first place! If you have 2 parallel runs of conductors for example, use 2 conduits with one conductor of each phase in the same conduit.

I got the impression he was talking about using MI ?

 

[vinod]

The most common way to prevent this of course is to not pass single conductors through separate penetrations in the first place! If you have 2 parallel runs of conductors for example, use 2 conduits with one conductor of each phase in the same conduit.

In our case,There is no other way to install the single couductor than run seperatly. Any way we instrcuted to the contractor to change the gland plate with an non-magnetic material.

Thanks alot for your valuable feed backs.