VFD Cost Savings
VFD Cost Savings
(OP)
I've been doing some research for my company and have to present how much I can save the company by going to VFD's instead of direct induction (starter application). I don't get the option of a test bench or wind tunnel, so please help me if you can. We have approx. 36 fan applications, dust collection, and from what I've beed finding is that if I go to VFD's without varying the speed (Working on this later) there would be a cost reduction in KW used. Tests I've seen online suggest that a VFD is approx %40 more efficient, delivering the same HP at a reduced cost. Please respond.





RE: VFD Cost Savings
RE: VFD Cost Savings
A typical efficiency of a VFD is between 96~98% (and that is tops). So that's an additional 2~4% loss you would be adding into the system (at best), and that's without the effects of adding VFD's to the process (increased EMC, increased harmonic content, cost of installing, cost of cabinets[dust=tight control of enclosure] as well as the [potential] impact on the motors). However, all things considered, I would look at your application a little more carefully and investigate the possibilities of varying the speed if it is fans you have. I've worked on dust extraction systems in aggregate quarries and there are savings to be had as long as you have good control over the pressure differential of your dust extr. system and feed this into your VFD's rather than dampers (if it's a similar system).
RE: VFD Cost Savings
RE: VFD Cost Savings
RE: VFD Cost Savings
The only similar application I have seen where the VFD made sense is in dryer blowers at car washes. If the dryers have electric heating elements, as some do in colder climates, you need to keep a minimum amount of air flow going across the heaters in between cars to avoid having to either take too long to re-heat, or burn up when the blowers are off. In older designs then, the blowers were just left running. In that case, they could save energy by leaving them running but at a reduced speed; just enough to protect the heater elements, then ramp them back up as the next car became ready. In your case though, there is no benefit to keeping the bowers running is there?
RE: VFD Cost Savings
RE: VFD Cost Savings
For those looking for other areas to save on energy, HVAC has huge savings, now if I can only find the time to do those calcs.