With all the talk these days about “Green” this and “Green” that, eventually you have to start wondering about your own “carbon footprint”. In our industry, Everything… Is… Of…or About… Energy. So I had the thought: each of us is in one way or the other, concerned about the cost of energy. There is the “cost” in terms of what energy use does to the environment; or the cost in terms of how it affects your bottom-line.
As humans, we all tend to be short-sighted. Most of the time, things have to be pointed out to us (hopefully by someone smarter than we are) for us to take note. Getting to the point, I was recently introduced to a product (by some really smart people) which really made sense to me. I’d like to share it with you, because it addresses at the same time – both the bottom line cost and the long term impact of energy use.
Bear with me here. Most 5th Graders know that when a motor starts, it uses electricity. Electricity costs money. So if you can create something which only uses as much energy as necessary and no more, then you really have something! That (ask any 5th Grader) is why Inverters (or Variable Frequency Drives) are so cool! If you have something in your little plant or giant factory which might use 10HP, you have to have a 10HP motor. But if most of the time you only use 5 HP, and can “turn down” the motor where it is only developing 5 HP – then it only uses the energy of a 5HP motor. Need only 1.5 HP? Turn it down and reap the savings. Neat, huh!
So for the past decade or two, Inverters (I like to call them VFDs or just Drives), have been the “cat’s meow”. So much so, that the electrical company even gave people money back on their bills, because they didn’t have to build new power plants. Now, let’s move on to 6th Grade stuff.
We all know (see above) that motors use electricity, but how many of us knew that (4th Graders pay attention here) motors can MAKE electricity? Yep! They really can. And they really do, when the guy in the control booth (actually he is a computer, but don’t tell anybody) tells the Inverter to slow the motor down, electricity is actually made by the motor! Now the Inverter has to DO something with that electricity. So it turns it into heat! That is a bad thing. What’s worse, is that if the guy in the white shirt and tie up in the front office says to slow the motor down even faster, then the Inverter gets connected to a big toaster (we call them “Dynamic Braking Resistors”, but they really are just big toasters. Without the toast.) Big Toaster = Big Heat = Wasted $ = Bigger Carbon Footprint. That’s a bad thing.
So these smart guys I know (not really, but it makes me sound way cooler than I am) came up with a really clever idea. What if you could throw away that big toaster, and take that electricity that would have been turned to heat, and (now get this) SELL IT BACK to the electric company??? Whoa! Now you have something to write home about! Well to be honest, “sell it back” might be a bit of a stretch – “have it available for use elsewhere” in your facility might be more accurate. But the end result is the same.
This “gizmo” is called a RCU – “Regenerative Converter Unit”. Here are the details: Vertical lifting machinery or high inertia loads like elevators, cranes, centrifugal fans and centrifuges contain potential energy and inertial energy when operating. When the motor is operated by an inverter, this energy is converted back into electrical energy when the devices decelerate, lower or stop the load. This electrical energy, called regeneration, flows back into the inverter’s DC bus, causing the voltage to rise.
• Traditionally, this regenerative energy is dissipated as heat through dynamic braking resistors, and is therefore wasted.
• The RCU series Regenerative Converter can provide up to 40% energy savings, by reclaiming that regenerative energy and feeding it back into the AC supply.
At this point your head jerks towards me (and the 6th Grader named Paul), and you say “How can this be”?
Well, the RCU Regenerative Converter reduces electric power consumption by returning the otherwise wasted energy to the AC power distribution network for use by other loads. Additionally, because there is no heat generated by braking resistors, the capacity of air conditioning systems in the electrical room can be reduced, further reducing electric power consumption.
I started out this blog talking about energy. The RCU is also ideal for use in “Renewable Energy Systems”, like Solar/Photovoltaic systems, Wind Turbines, and Fuel Cells. So I’ll end as I began, by using the (by now almost overused) term, “Green”. If you are reading this blog on a webpage called Lighthouse PLCs, Inc., you are most likely involved in some fashion with the manufacturing industry. You are the guys and gals who make the stuff we use every day. (Thanks, by the way.) But it isn’t everyday that we at Lighthouse get to offer you something that at the same time helps your bottom line and also helps the environment. That, my friends, is pretty neat! And you don’t have to be 6th Grader to appreciate that.
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