Lead Power factor 1

[Humble2000]

Is there anything wrong to have a lead power factor?
We just injecting reative power to the utility right?
I have specified a capacitor banks that will fix the power factor to above .95;however if the load drops the power factor migh lead.
I am aware of step cap. banks but I just want to know what would happen by having leading pf?

 

[davidbeach]

MineGuy, for a load of x kW at a power factor of .909, leading or lagging, you have an apparent power of 1.1x kVA. Given a voltage, that kVA can be converted to amps, and those amps, squared, times the resistance of the line is your losses. It doesn't matter whether the current is leading or lagging when considering these losses.

 

[asvcmaster]

Humble,

I have recently commissioned a 4.3 MVAR\Phase Ungrounded Wye PF Bank at a Clients Shredding Operation (4000 HP Wire Wound Rotor w\Liquid Rheostat). It is Tuned to the 9.8th Harmonic.

At Idle the Bank leads a bit, and it is .94-.97 under load.
The serving Utility does not care about the Leading VAR's, and in this particular application, they will rarely be at Idle.

I would have to say, the Utility, and Application will determine if you can get away with the leading KVAR's.

Mike

 

[davidbeach]

In the Pacific Northwest, the principal wholesale power provider, BPA, charges their customers, primarily distribution utilities, a penalty for any power factor below .97, leading or lagging. I did a long underground feeder fed by one of those utilities once, and they were very concerned that I wasn't going to cause the the customer's load to go leading due to cable capacitance. Fortunately, at only 14.9kV, the added 4.8 miles of line wasn't going to become a problem. On the other hand, it was amazing how little voltage drop there was at the end of an 18 mile underground circuit (of which the 4.8 was about in the middle), even with a several hundred percent change in load between summer and winter.

 

[Robert789]

Assuming that we are dealing only with a distribution circuit and not generators, I would mainly be concerned with voltage rise. If I have the equation correct, the voltage rise can be calculated from the source impedance as follows:
{((KVAR per Phase)/(KVln))/Ibase} * X1 = %VR

The utility won't have to have additional capacity to carry the leading VARs because this will be during periods of light loading, the capacitors will result in freed capacity during peak load periods.

From the utility perspective, I would rather have you be at 95% lagging on-peak (when VAR support is most needed) and 95% leading off-peak than to have you at, say, 90% lagging on-peak and unity off-peak. {But our accounting department would still insist on charging you the leading power factor penalty}

 

[DaveScott]

I wonder if there are any tuned circuit difficulties, for example, linking a capacitive site to an inductive site?