Automatic Power Factor Correction Systems

DEAR SIR,

YOU REQUIRE AUTO MATIC POWER FACTOR CORRECTION PANEL. ELECTRICAL CONTROL PANEL BUILDER SUPPLIES THE SAME.

WHAT IS THE LOAD IN YOUR SYSTEM ?

kva DEMAND ?

WITH THIS, YOU MAY FIX UP YOUR REQUIREMENTS.

REGARDS

I'd tend to agree that at load would be a good place to start. There are probably a few large motors that are hurting you the most. In which case you install power factor correction at the motor, either with caps or with VFDs. You could also consider replacing some medium size induction motors if they are 30 or more years old. New motors meet higher efficiency and PF standards. If you have any voltage control at all (transformer tap changers), you'll want to make sure you watch it close. Letting the voltage get too far above or below nominal can have a detrimental effect on PF and efficiency. I'd also put in my own metering and data logger. Start compiling some historical data. You'll need it for project justification or even to work a deal with the power company. It may be that you can get them to give you a break on the PF except for the system peak hours, ~7a-9a and ~5p-7p.

Thanks for the options explanation. So far what I have been looking at it the Automated full building PF correction. I am finding so far that it may be the best fit for us, as we do not have what would be a continuous steady load even when the whole plant is running. We are a printing facility with multiple presses that are constantly being started and stopped throughout the day at different intervals.

The 2 companies that I have looked at so far are Benshaw and Electrotech. Both tout have fully automated control systems with filtering and alarms for functionality. I run a number of inverter drives on motors here as well as VFD's. Added to that we have about 40 PC's throught the building and multiple PLC controlled machines.

My input voltage to the building is 480v from a 500KVA transformer. this comes into a 1200A distribution panel and is distributed after that into a centrally located MDP that feed all the step down transformers in the building. We are using voltages at 480v(machinery), 277v(Flourescent lighting), 208v(more machinery), 120v(typical office equipment). The electric company tells me that we are running at about 65 - 70% PF currently.

The maximum load we usually get on the building in the middle of summer is about 520 amps with everything running. The main reason I am looking into the full building Automated system is convenience. Being the only person in the building to take care of all the machines and the facility equipment, I have a lot to keep up with already and I would really like to have a set it and forget it type system. But I can see your point with reliability. I am hoping for a smart systew that will tell me whats wrong when it's wrong.

Please let me know

Sorry forgot to include some information on the load side.

Not sure how important it is in detirmining correction but we have 19 UV curing reactors for drying the ink after its printed. All have ballasts and aside from the varying lengths on the bulbs all generate about 9600 watts per unit of very intense UV light. These are a constant throughout the day and are only turned off at lunch and quitting time. Other than that they run about 20 hours per day 5 days a week.

It seems that a large fraction of your loads generate harmonics. This can be a big problem with standard capacitor banks. You will most likely need de-tuned capacitor banks to resist to the harmonic currents and avoid resonances.

You can contact the company called "Inelap S.A. de C.V." for custom equipment and harmonic analysis. I have worked with their equipment in the past with good results in difficult industrial environment.

Power factor compensation system are a double-edged sword, make sure you deal with competent people. If the salesperson says it's easy, you only plug the capacitor bank here and the problem solve, call somebody else...

Good luck.

Depending on the amount of money involved and your peak load requirements, you may want to revisit some of the ideas they had in the 1920's.

One scheme used back then was to install generators as sets, both generators would have dis-connect couplings between the prime mover and generator. The operation method was; when synchronous condenser operation was desired one unit would be dis-connected mechanically. The coupled unit would be started on turning gear, the uncoupled unit (synchronous condenser unit) would be electrically tied to the coupled unit (power producer) and both units brought to line speed and synchronized. Once they were on the line both could be excited separately.

The beauty of it was that if you really needed power you could couple up the odd unit and generate real power.

Or so my feeble old memory tells me.

Very interesting concept. Sounds like a coslty initial investment, although I have been trying to get my company to invest in a backup generator.

double j b,

Lots of good advice from Jraef. I would amend his comments a little:

• When you add PFC to individual motors, if it is located after the contactor and wired in parallel with the motor, you need to resize or adjust the overload relays for the reduced full-load current. This is a code requirement (either directly or indirectly because the PFC manufacturers say to do so).
• If you have some medium or large motors and a host of smaller ones, you can consider individual correction for the large motors and a small amount of additional PFC's that are connected to the group(s) of motors with separate contactors and separate controls.
• I believe that synchronous motors get less attention than they deserve. True, they have additional maintenance requirements because of the excitation requirements, but they are capable of infinite control of the PF correction, instead of step-wise control. Also, you do not have individual contactors to worry about.

I'm glad your utility is giving customers time to prepare.

--JMM

This is a bit off topic but have you considered investing in a wind and solar system instead of a backup generator? This would pay for itself over time and then reduce your electricity costs in the future. I would think that Oklahoma would be a good candidate location for such a green approach. I would bet also that there would be some government incentives to implement this now.

Wind and solar is a good idea. Its a bit out of my realm of expertise, i.e. sizing of the system and all the engineering that goes with it.

Isn't it a bit cosly to get started as well? I have also heard that the ROI is pretty far out there.

Right now I am concentrating on getting the PF under control but I appreciate the suggestion it is food for thought.