What Happen If Cables Placed In Magnetic Metal Conduit

What Happens If Cables Placed In Magnetic Metal Conduits 

Do we know what happens if cables are in a magnetic metal conduit? Yes, at least we know that in any circumstances, the individual phase of an AC (alternating current) circuit is in a separate magnetic metal conduit. 

Most of us follow these important rules for cable installation, but everyone can’t explain why we should follow this; what happens if an individual AC phase is placed in a separate metal conduit.

Yes, of course, some of us are a little advanced; we know we don’t place individual ac phases in metal conduits because excessive heat may occur in that situation. 

Separate phases should not pass through magnetic structures because overheating can occur due to excessive hysteresis and eddy current losses.

Already, a question arises, is it acceptable to pass all the phases together through in a magnetic conduit? Yes, it is wise to pass through all the phases in any magnetic enclosure simultaneously so that maximum cancellation occurs of the resultant magnetic field. 

This procedure huge reduces the magnetic field, though increases the skin and proximity effect of cable. Because of proximity of magnetic materials some losses occurs in conductor just placing the cable near the magnetic materials, amount of losses depends on volume of materials.

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Skin Effect:

In an AC circuit, current tends to flow through over the outer surface of a conductor than the inner side, which means that current density is greater near the outer surface of the conductor. This effect is called the skin effect. 

Due to the skin effect, a long cable center axis is surrounded by a more magnetic field than the surface, as a result, inductance increases toward the center. Finally, resistance increase and conductance decrease in the center than the surface.

 Proximity Effect:

If AC conductors are placed closely, there is a tendency for the current to shift to the portion of the conductor that is away from the other conductors of that cable. This is called the proximity effect. 

So, we can say that insulated conductors should not be installed in metallic conduits and also not run close to magnetic materials. For example- high-voltage underground power cables frequently need to pass along metallic materials like gas pipe lines, water pipe lines, etc. which may be dangerously electrified by induced voltage if not properly grounded by both metallic pipe and cables' metallic sheath.