Trefoil cable installation

[Colinjohnson]

Could anyone advise why power cables are arranged in trefoil groups ?
I suspect it is to negate induced or circulating currents but are there any publications which deal with the subject ?

 

[Skogsgurra]

Are you talking about overhead lines (where three conductors are sometimes seen bundled) or is it about the cores in a cable?



Gunnar Englund

http://www.gke.org

 

[cuky2000]

Here are some advantages of the trefoil configuration over irregular phase arrangement:

1- Trefoil configuration produces less reactance than flat configuration. For instance, in three contiguous insulated conductors the trefoil reactance is around 25% lower than flat configuration.

2- Other configuration may require transposition to balance the voltage. However, since the trefoil arrangement has inherent balance mutual inductance will not create unbalance voltage.

3- The EMF in trefoil is minimum since most of them are cancelled each other in a three phase system.

 

[Colinjohnson]

cuky2000. Thanks, I thought that was it but wasn't sure. Having checked Pirelli data I note that they actually state the inductance in trefoil for SC cables.