Best Equipment for Power Factor Correction/Best Analyzer for the same
Best Equipment for Power Factor Correction/Best Analyzer for the same
(OP)
I have seen the GE PFC equipment and am leaning towards it, but wondered also what equipment to use to analyze PFC in large industrial plants.
Any suggestions?
Any suggestions?






RE: Best Equipment for Power Factor Correction/Best Analyzer for the same
Bill
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"Why not the best?"
Jimmy Carter
RE: Best Equipment for Power Factor Correction/Best Analyzer for the same
"If I had eight hours to chop down a tree, I'd spend six sharpening my axe." -- Abraham Lincoln
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RE: Best Equipment for Power Factor Correction/Best Analyzer for the same
Bill
--------------------
"Why not the best?"
Jimmy Carter
RE: Best Equipment for Power Factor Correction/Best Analyzer for the same
You also need to determine if correcting the PFC will result in some kind of tangible benefit such as savings in money and reduction in penalty. You may find this of interest www.sre
Rafiq Bulsara
http://www.srengineersct.com
RE: Best Equipment for Power Factor Correction/Best Analyzer for the same
The answers here sound like there is a couple of machines in the factory at fault for bad PFC. I am talking about a manufacturing facility with over a hundred machines.
RE: Best Equipment for Power Factor Correction/Best Analyzer for the same
GE, Eaton, Siemens, SQD and the like, all make such systems. Do a web search.
Or perhaps you can rephrase your question, if we misunderstood.
Rafiq Bulsara
http://www.srengineersct.com
RE: Best Equipment for Power Factor Correction/Best Analyzer for the same
I have a large industrial customer. They have many induction motors in manufacturing equipment, many VFD's and large AC units to boot. Do you recommend and individual assesment of each machine? Or do you recommend a automatic PFC system? Also, how do you assess/prevent harmonic problems that can be caused by PFC correction?
RE: Best Equipment for Power Factor Correction/Best Analyzer for the same
VFD should have no power factor issues, plus they do not like capacitors. Depending on the details and scale of the system, a system simulation on a software may be required to perform an harmonic analysis. The existing harmonic spectrum analsyis is needed first, which is relatively simple using a PQ analyzer.
In the original post you indicated you are already leaning toward GE PFC equipment..how did you reach that point without an analysis?
Rafiq Bulsara
http://www.srengineersct.com
RE: Best Equipment for Power Factor Correction/Best Analyzer for the same
Waross' amendment to my suggestion makes the best sense; start off correcting the biggest offenders, then expand down from there until you have the situation under control. APFC systems try to do this digitally by adding and subtracting caps, but Murphy rules the world and any glitch affects the entire network. If you must consider a bulk PFC correction system, try picking your largest running continuous load and put a Synchronous motor on it to run as a synchronous condenser. I even know of a couple of facilities that have a large synchronous motor operating as a condenser with no load attached at all! That's because, as Rafiq suggested, they did an in depth evaluation of their penalty situation with the utility and discovered that even though it appeared to be a "waste", the economic benefit was enormous.
"If I had eight hours to chop down a tree, I'd spend six sharpening my axe." -- Abraham Lincoln
For the best use of Eng-Tips, please click here -> FAQ731-376: Eng-Tips.com Forum Policies
RE: Best Equipment for Power Factor Correction/Best Analyzer for the same
Back in the old days, everyone assumed 'bad power factor' was an inductive load and could be corrected with a simple application of caps. No more. Power factor now includes the circulating harmonic currents that many non linear loads draw and must be corrected with different equipment.
Make sure that whoever does the study, they consider the harmonics problems in addition to inductive loads. And if your solution is in fact a capacitor bank, make sure that the plant down the road doesn't have a bunch of VFDs, or your caps will become a sink for their harmonic currents.
RE: Best Equipment for Power Factor Correction/Best Analyzer for the same
RE: Best Equipment for Power Factor Correction/Best Analyzer for the same
There is also a problem with automatic PFC control with switched capacitors if you have an ungrounded grid (IT grid). The switching sometimes causes transients that fry the VFDs. Be sure to make the switching in the zero crossings and you will not have that problem. But - you must make sure that you have a very reliable system. One false swiching can harm your VFDs.
Gunnar Englund
www.gke.org
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100 % recycled posting: Electrons, ideas, finger-tips have been used over and over again...
RE: Best Equipment for Power Factor Correction/Best Analyzer for the same
1> Investigate the tariffs and the basis for PF penalties.
2> Request several years back power bills. (The instrumentation to measure the PF that is incurring penalties is already installed by the utility.
3> When you have the information, build a spread sheet and look at how many KVARHrs per month you need to get above the penalty threshold. Divide down to KVARHrs per Hour.
4> Look at which machines may be corrected to 100% and calculate how many KVARHrs per month you may gain from each machine.
This is the low hanging fruit. This method is not always applicable and may not serve as well for distortion PF issues, but it is quick and dependable and economical where it may be applied.
If the low hanging fruit will do the job, why do more?
I explain to the customers that there may occasionally be small penalty charges but it will probably be cheaper to pay the occasional charge than to avoid it.
Bill
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"Why not the best?"
Jimmy Carter