Thanks for the comment, Jack. There definitely is a need for more education on energy saving possibilities with VFDs, although I think the suppliers are trying to be effective in this area. There are also different types of incentives to help accelerate and finance ROI.
You're absolutely right, apresher. VFD's have a whole range of applications where they signficantly improve efficiency. I think the vendors need to be more proactive in selling these features and showing the cost savings.
Good article. Certainly it's well-known that variable frequency drives will save on energy costs if properly applied. Vendors provide both assistance and calculator applications to help identify and cost justify these newer systems. But the potential savings also go beyond traditional pump and fan applications to other areas such as regen, power factor and common bus applications. Some companies seems determined to seek out savings while others are much less aggressive in investing the engineering it takes to reduce energy costs.
IT should not be any surprise that using a VFD to reduce the power applied to any process that requires less than the maximum capability of a prime mover will reduce energy consumption and power waste.
Any process that does not need full power constantly should be examined as a candidate for a VFD, although in some situations it may not make economic sense. Variable energy input control can be extended to other areas as well. In pneumatic systems, as an example, all of the energynused pushing air through undersized piping to provide adequate flow is wasted. The fastest way to see if that is happening is to observe the cylinder pressure and see if it continues to rise after the cylinder stroke is completed. The same applies to hydraulic systems and cylinders. An added advantage is that larger piping can provide faster cycle time, usually without any increased energy consumption. OF course, in hydraulic systems a VFD can provide for inceased pump delivery only during the periods when high flow is required, which can result in a very large improvement in overall system efficiency, and as a free bonus it can reduce system cooling requirements quite a bit. In fact, in at least one application the use of a VFD for hydraulic pumps reduced power consumption by more than 50%, with no compromise in performance at all.
This is another great example of industry becoming more efficient. As the article points out, industry uses a third of the energy used in the US. The opportunity to improve efficiency in these areas is great, and this opportunity comes mostly from better engineering. There is a lot of talk about green computing, but this is a much better area to concentrate on. The payback is greater.
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