VSD Efficiency
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We all know that Variable Speed Drives (VSD’s) can provide significant energy savings in the operation of pumping systems, but many people overlook the added energy savings from the efficiency of the variable speed drive itself, and the environmental benefits available when installing.
Purchase price and installation costs typically only represent 5% of the life cycle cost of the drive installation.
In this article, we will look at these two aspects in isolation. Understanding these issues will add significant savings to your overall installation.
VSD Efficiency
There are many drives on the market these days, and it is a competitive environment. Purchasing the drive is the first step in your process life cycle. Maximising the return on investment should be a key factor in your purchasing decision, so looking beyond the initial purchase should be considered. Danfoss VLT drives typically offer a 0.5 to 2% better installed efficiency to traditional drive installations. When energy costs represent 95% of the lifecycle costs, this can add up to substantial savings, especially in pumping and fan applications.
So how do Danfoss do this and what does it mean for your life cycle costs?
Danfoss VLT drives have DC Chokes fitted as standard across the entire range. Whilst this significantly reduces the harmonic distortion footprint, it also provides leading class efficiency compared to drives with optional line chokes. Although the nett harmonic benefits are comparable, line chokes contribute to voltage drop across the drive which can in turn reduce the DC Voltage and limit the output capacity of the drive. DC Bus Chokes on the other hand, do not have a voltage drop so the maximum power can be realised from the drive.
(Please note that AC Line Reactors are quite suitable in some installations with transients).
(Please note that AC Line Reactors are quite suitable in some installations with transients).
The following link provides a detailed overview of life cycle considerations for your VSD installation. Please have a read through this guide, or download for future reference, as it may highlight areas in your plant where improvements can be made.
