Power Factor and Sizing of Conducters

[mgmsparks]

Apparent Power is used for the sizing of equipment like tansformers and panels, but do we need to consider it when sizing conductors?

 

[charlie b]

Yes, sort of. You size conductors for the calculated load amps. You get the load amps from the calculated VA of the downstream loads.

 

[72.5kv]

Like the transformer and the switchgear, the conductor has to be able to carry the active and the reactive current.

 

[weressl]

Apparent Power is used for the sizing of equipment like tansformers and panels, but do we need to consider it when sizing conductors?

Power factor improvement can lower your ampacity and can be used to provide additional available ampacity on existing feeders and to allow smaller size feeder conductors in distribution.
Actually that is why the POCO penalizes low power factor customers, since they need to provide larger infrastructure to support it.
On multiple, variable load structures automatic power factor correction - that switches capacitor banks in and out based on the set power factor target - may be warranted.
Individual motor feeders are sized according to NEC that makes no allowance for power factor, or for high efficiency motors, or motors that are never fully loaded. IMO the Code should make allowance for systems under engineering supervision in that respect. Installing capacitors on individual large motors can result in lower currents on ther MCC main feeders, therefore reducing the actual demand current on the MCC or switchegar feeders and the power factor correction in that case is automatic.