How Do I Improve My Power Factor?

Earlier PFC units I fitted had the monitor incorporated in the unit. Later units monitored the intake.

Were are monitoring the CT's fitted?

The Panel has monitor incorporated in it.

1. A lack of coordination/calibration between the APFC and the utility meter should be suspected.

2. Yes, overcompensation can lead to resonance, harmonics, transients, and overvoltages that can lead to costly equipment damage and subsequent downtime.

3. If your PF is close to unity what type of improvement are you looking for? PF improvement during light load conditions is very difficult to achieve, and may not be cost-justifiable. What is your goal?

PF correction during light load conditions is justifiable in my case, it could result in reduction of utility bill from 20 to 30%

An overview of your usage, KW, Kvar, PF, and calculation of PF penalty would be interesting - ie: a copy of a couple months bills and meter readings.

I will post all calculations by tomorrow for your perusal

Here is the Analysis of previous bills

We are billed on KVA and no extra penalty is levied for poor PF. So Basically all the kVArh is our penalty/loss

Here is the analysis of this months' readings. Note that 13th December is the date when we stared to keep 5KVAr Capacitor in Service during ShutDown period.

How long where you down?

The KWH reading is only increasing by .7 to .9 each day. Is that x 300?

Your overall PF for the month is only .79 - could stand some improvement.

There is something funny - for some periods you are using more KWH than KVAH. With unity power factor at best they should match.

Yes the kWh reading is * 300. The Avg PF post 13th December is 0.93.

Where do you see more kWh compared to kVAh?

Dec 17 - Dec 18 its close - may be round off error.

Is the whole month light load?

About 20 hours a day is light load.

Dec 17 - 146.7 kWh, 233.8 kVAh

Dec 18 - 147.4 kWh, 234.6 kVAh

KWh = 0.7

KVAh = 0.8

kVAh is more than kWh.

Take a hard look at the accumulated KVARH when you are loaded for those 4 hours - I suspect that is your $ accumulation. What is the accumulated KWH and KvarH during those 4 hours?

What KWH and KvarH do you accumulate while lightly loaded?

You need to proportion the cost to the actual activities.

(the print out here is small - my eyes might have crossed.)

Please provide a copy of your utility's tariff for your particular level of service, it is the only way to know exactly how you are billed, especially when it comes to demand, seasonal, and power factor penalties.

1) The difference is due to the utility company meter being affected by their electrical distribution system PF status whereas the APFC is only capable of controlling the PF on the attached downstream equipment load.

2) Maybe yes, maybe no. I would contact the APFC OEM and ask them if there is any possibility of damage to the unit if operated in overcompensating mode.

3) Based on the fact that leaving the 5KVAR capacitor in service when the system is shutdown improves the meter PF indicates the need for adding more capacitance rather than subtracting/lowering capacitance.

If the APFC manufacturer approves doing so I would put the 10KVAR capacitor in service with the system down to observe the impact to meter PF.

If the 10 KVAR capacitor is too large I would add a 1KVAR capacitor then observe the rate of meter PF improvement which would indicate the added capacitor value needed to take the meter PF to unity. (1)

In order to improve the PF you must determine if additional capacitance is required or if you need inductance.

If you have not done so already I would contact the utility and ask if the distribution line feeding your facility has PF compensation on it.

If so; it could be that they can adjust the PF from their end when your plant is off line.

1)I agree with your analysis, previously I had PF checked with main electric panel switched off and Utility meter PF was recorded around 0.25.

2)I would go ahead and check with 10KVAR capacitor and revert back

Thank you very much, your answer was very helpful!

"...1) The difference is due to the utility company meter being affected by their electrical distribution system PF..." Impossible, the utility meter only responds to the quantity being measured on the load-side, the characteristics of the load haven't been changed.

"... it could be that they can adjust the PF from their end when your plant is off line..." No, utilities use capacitors to manage terminal voltage not power factor at their distribution point. Again, they have no reach beyond the meter, just like a capacitor at the terminals of a motor has no effect on the internal characteristics of the motor.

On the flip-side, changing the voltage on the line-side of the meter does have an effect on the operational characteristics of the motors, but the impact is only incremental, highly non-linear, and highly dependent upon the nature of the loads. In order to model the effect it is necessary to model the speed-torque characteristics of every motor and its process parameter loading as part of an overall plant load-flow analysis. When the utility voltage is kept within established legal limits the pf impacts are typically around +/-1%.

When lightly loaded (low Kwatts) a poor power factor usually has a low total KVAR load - and the penalty for poor power factor at that time is insignificant - but that always depends on how the utility calculates your penalty. From the $cost does it make any sense to chase it?

From my experience the $cost comes in peek demands (at the wrong time) and poor PF under load (a high total Kvar load with high Kwatts).

As others have stated - a leading (over compensated) system may be prone to over voltages that are damaging.

What does your history tell you? Are there any times when all of the capacitors are activated? For instance, maybe you could ditch one of the 50 KVAR and throw in some more capacitors at the lower end for better tuning to low loads.

That's really a good feedback you could give to PF company.

Here you might get something useful and beneficial.

The utility companies in the US., are only concerned with unbalanced load of your company. At .2 to .5, the utility would not bother with a charge do to the paper work being more costly than the charge would be. The difference in meter amount is probably just the difference in calibration between yours and theirs anyway.

Absolutely false, properly calibrated kWhr meters are totally indifferent to the degree of unbalance of the loads; however, your equipment will suffer the consequences of the resulting excessive negative and zero sequence currents.

On the other hand, if your unbalanced loads are causing poor power quality problems for other customers on the same feeder circuit, you can be sure that the utility will be knocking on your door with a "Stop and Correct" legal notice.

And you can be sure that if you're a commercial tariff customer with PF below their limits you will find a PF/kVAR meter attached to your service and you will be billed accordingly, maybe even for the cost of the additional metering!

If your meter is reading a power factor below 0, there will be a reading as such. A power factor meter is in fact a meter which means it can have a difference in reading from two meters. especially at .2 reading.

Properly calibrated utility/instrumentation/billing meters that don't match with a known standard are defective and should be removed from service.

To say that a "...meter is in fact a meter..." follows the same logic that says a "...Corvette is the same as a Pinto..." because they're both cars.

"To say that a "...meter is in fact a meter..." follows the same logic that says a "...Corvette is the same as a Pinto..." because they're both cars."

Not if your meters are recording the same information. The brand might be different, but the working part of the meter better be the same in both.

There is no such thing as a power factor below zero. Sheesh.

I was just talking about meter movement.

Wikipedia gives a closed intervalof -1 to 1 (leading or lagging PF)

https://en.wikipedia.org/wiki/Power_factor

That article is a prime example of Wikipedia's main shortcomings, the fact that an article is not critically reviewed and that anybody with a computer can author/edit whatever they please. Nobody who understands what power factor is (and is not) could possibly agree with everything that is written there, nor would they quote it as a reference.

PF = cos(phi) in a power diagram - and since the cos (phi) = cos (-phi) the PF is positive.

However the concept of leading and lagging PF is critical in calculating the appropriate compensation. The vector diagram definitely shows this, but the PF alone without the leading or lagging added (+/-) becomes misleading.

The power company bills on the PF leading or lagging - so it is not material to them in $, but if you have a significant leading PF they may not be happy with you in the long run because it tends to destabilize the system.

Since this has turned into an "excited" conversation, I will throw in my two pennies worth.

Lead vs. lag matters a great deal. In fact, your capacitors are "lead" elements in a circuit, in that current flow leads the voltage, whereas motors, lighting transformers, fan motors, pump motors all use considerable amounts of inductive elements and inductive finite elements (motor winding, etc.) are lag type elements, in that current lags behind voltage. Lag produces a phase shift that results in reduction of the power factor from unity to a lower number. If too much capacitance were somehow added, there would be a shift to unity (actually past unity), into a leading system that is actually attempting to pump VARS back into the grid (or just cause a wicked high over-potential that will damage local equipment).

If one wishes to improve the low load power factor, adding substitution values of capacitance is a reasonable trial and error method of "getting it right". However, what if your lowest substitution value is too much, and you are actually over-compensating? You need to be logging all the mains parameters during the high load and low load so you will get a feel for voltage, phasor diagram of your overall local load.

One other option (probably only in the largest installations with huge inductive loads), is to go out and purchase a synchronous condenser (motor spins this up to synchronous speed with grid 3-phase), and the level of excitation is kept higher than what it would be in generator mode, thus by making continuous, time-appropriate adjustments of the excitation of this element, the overall local load is adjusted to have very near unity power factor at all times. Installations of synchronous condensers will require the help of a reputable consulting engineering firm who could recommend a properly sized unit, or less expensive substitution values of capacitors (that unfortunately are not continuously adjustable).

I think I have used up my two cents worth.

"excited" conversation - - at least it is retaining a semblance of civility.

Why have civility when a rant or two would be perfectly normal in Parliament?

Lawyers and embezzlers and philanderers and self serving egotistical people. Parliament is not a good example.

Parliament, and US Congress are two completely fine examples of organized chaos. Chaos will do what chaos wills to do. In the meantime, the monkey in chief keeps ordering all these executives (executive orders). You would think people would get tired of this bull sheite, and ride him out of town tarred and feathered and on a rail. I certainly am tired of this faggot getting on TV and making speeches about how we need more gun control. NO. What we need is more guns, and a hell of a lot more ammunition and the sooner the better.

Chaos is rampant, and only the civilized (whoever has the most guns) will survive in this monkey cage gone wild.