How to Achieve Power Factor Improvement??

Waterlucky, Step 1. Find your existing pf on peak load conditions. A good powermeter at the source will help you in this. Step 2. Find the necessary capacitors ( kvar) required for the improvement (say to 0.95). No, the OEM will not supply you PF correction capacitors for the equipment unless specified by you in order. Good luck

Hello waterlucky,

"also in reality, does PF always less than 1; even after improvement??"

The cost of attaining Power factor of greater than 0.95 is not economically practicable.

Regarding where to instal PF correction equipment, in an installation, please see my earlier answer here:

http://cr4.globalspec.com/comment/145220/Re-DG-running-at-unity-power-factor

If you need further help, please reply....

With the exception of discharge and fluoresecent lighting,which are already fitted with the correct power factor correction capacitors,most other plant will not have or be offered with power factor correction.

Local distribution boards and motor control centres at 415V are the most common place to site power factor correction capacitors,with automatic controls and contactors to switch in capacitors as required.Overcompensation must be avoided as most suppliers charge for lagging or leading pf,and there can be serious technical problems as unity pf is approached near a load.

As has been pointed out unless there are other reasons for improving power factor,e.g.supply or generation capacity,the charge made by suppliers for low power factor must be balanced against the cost of installing and maintaining pf correction.Capacitors these days only seem to last at max 5 yrs.

Manufacturers of pf capacitors will often give you a free survey,and propose a plan for capacitors and controls throughout your plant.

I hope that I have not just restated what is in other respondents links,if I have I apologise to them.

You can go in for a centralized capacitor bank on the HV or individual capacitors on major equipments or capacitor banks at each of the unit substation bus bars on LV.HT capacitor will workout cost wise better.But if your diversity factor is high u may go in for LV at each unit substation.A clear solution can be be tried if we know ur power distribution arrangement.

Power factor has raised its wearisome head again in recent years. In the good-old bad-old days equipment manufacturers regarded power factor as a SEP - someone elses problem. Actually this was OK - you knew where you stood. PFC was simply an economic problem and easy to financially justify. Utility companies charged you for bad PF = saving per year = payback. Done.

Technology then gave us the 'smart' sampling electricity tariff meter. Utility companies were overjoyed at charging their customers per minute, per day, per week, per month, per season, per kW, per kVA, per fuel surcharge, per 'just for the heck of it'. Financial modelling becomes mind boggling - even the utilties themselves have trouble recommending a tariff. That suits them just fine.

PF starts to improve. Flourescent lighting (yes and even halogen lighting) gets high frequency ballasts with PF=0.99, big induction motors get first soft start then variable speed drives, CRT displays disappear from the desktop and even big servers become leading power factor. Utility companies don't care - they just increase one of the other 'pers' listed above to maintain profit.

Now however we have to deal with all the harmonics the electronic devices listed above now generate. Earth and neutral cables start to overheat due to all the happy currents harmoniously bouncing around the power system. These are tricky devils to eliminate and will engage in all sorts of oscillating gyrations with PFC banks, whose capacitors are so overjoyed at the attention they will happily explode with delight and bring down your building with them. (A recent project was a pumping station where the capacitors literally evaporated. Luckily so quickly the fire did not spread. We measured over 25% THD, where the nominal would be 2%. The higher the frequency, the lower the capacitor impedance...).

So PFC calculations are tough. Extensive protection devices are required to protect your precious kVAR, and as mentioned in a previous post they tend not to last too long. Expensive inductors are required as filters too. In all my current projects, I do not specify PFC outright. I wait for a few seasons of electricity bills and then buy time on the CIAs fastest supercomputer to see if it's worth all the hassle. 9/10 nowadays - just pay the utility charge. Sad but true.

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Our factory is operation for 12 years, with ABB power factor control unit(you can set Pf index value) and now it is well operated. Therefore, please contact to your electric room maker of designer for best solution. And mention to your electric distributor law: with Pf=? you have to penalty or return electric fee.

Of course you must refer to above conferences.

Good luck!

The answers above are all good. Another option, if your factory uses synchronous motors, is to over-excite the field of the synchronous motor. This produces an effect similar to installing capacitors. One major advantage of this design is that the motor field can be easily controlled to maintain a constant power factor (selected for the most economical compromise between cost of electricity and cost of equipment). It also avoids the power quality problems (harmonics) which frequently occur when capacitors are switched in & out of service.

"also in reality, does PF always less than 1; even after improvement??"

Power factor can equal 1 (called unity power factor), but not exceed it. Mathmatically, power factor is the cosine of the angle between voltage & current. A cosine value can never be greater than 1.0. Increasing the capacitance effect beyond unity results in again lowering the power factor and reducing efficiency.

The company that I work for specializes in energy conservation projects. For the large facilities that we have done worldwide, placing properly sized capacitors as close to the load as possible is one easy fix to reduce the PF charge the utility company imposes. Most of the reputable Caps are put in parallel so if one should fail your equipment is just back to the way it was. In the whole project, Caps usually show a payback of just a few months and we have been implementing them for over 20 years, so its not anything new or experimental.