By Kerry Manworren
Every motion control system is different and unique. There is not a single universal answer, but there is almost always a possibility to increase your efficiency.
What is efficiency? Efficiency can be measured as:
First, look at every component of your system. Is the motor high efficiency? Are you using a Variable Frequency Drive (VFD)? Are you using a chain, belt or direct drive? Is your gear reducer a worm, helical, cycloidal? Are you driving a ballscrew? Is it a rolled thread or a cut thread? Of course, there are other potential components to a system, but we will only tackle the ones I have mentioned here.
HIGH EFFICIENCY MOTORS
Let’s look at the motor first. Is your motor pre EPACT? If so, it could be as low as 70% efficient, whereas a new motor will be at least 90% efficient.
VARIABLE FREQUENCY DRIVES (VFD)
A Variable Frequency Drive (VFD) can help you get your speed exactly where it needs to be without using various other components to try to come close to the speed you need to get your highest yield
CHAIN, BELT & DIRECT DRIVES
Chain drives are about 98% efficient but are limited by feet per minute. Belt drives are about 95% efficient and are better for higher speeds. Direct drives are the most efficient but usually the hardest to use because of the lack of torque and the excessive speed.
WORM, HELICAL & CYCLOIDAL GEAR REDUCERS
If you are using a reducer, the type will determine your efficiency. A worm gear will be 70% to 76% efficient. A helical or cycloidal will be 90% to 95% efficient.
A rolled thread ballscrew vs. a ground thread ballscrew is 10 times less efficient due to the co-efficient of drag. Look at your bearings, quality comes at a cost but a ground thread ballscrew will provide you with 10 times more efficiency.
You can always make a motion control system more efficient by looking at not only the drive components but also the system components. Request a payoff calculation, formulated by your local OTP Industrial Solutions sales engineer. Our mechanical experts can help you assess and drive efficiency into your motion control system.
By Alan Wharton
Technology improvements have made Variable Frequency Drives (VFDs) a more reliable and cost effective method of speed control. With the advancements of VFDs in recent years, they have evolved into highly sophisticated digital microprocessor controllers and high frequency power devices.
Now that VFDs have become so accepted in the industrial market, the potential for retrofits and new project installations remain very high. Demand for energy savings and process control will continue to provide double-digit growth for many years to come—and the two most common applications for maximum energy savings remains in centrifugal pumps and fans. With the recent requirements to reduce the overall demand on the power grid, there are many utility companies providing rebates and cost-sharing programs that, in some cases, will provide product at virtually no cost to the user.
History has shown that although you can achieve two to six percent energy savings with premium efficient motors over standard efficient (EPACT) motors, VFDs can provide up to 35 percent savings if applied properly. In many cases pumps and fans are sized according to worst-case-scenario using maximum flow conditions or by using a “rule of thumb” approach to apply a 20 percent oversizing formula. It is important to evaluate the complete application and system characteristics to determine the potential savings available.
In addition to energy savings, other benefits include the reduction and/or elimination of motor starters, less stress on the motor windings and bearings, and a decrease in stress and wear on the pump or fan itself. Taking all of this into consideration will equate to a smoother, longer lasting, more controllable and more efficient operation process.
Please contact OTP Industrial Solutions to receive technical assistance on how to apply VFDs to your application or to evaluate your process to determine potential energy and cost savings opportunities.
OTP Industrial Solutions for Electrical Applications
Written by Tim Griffith
October 22, 2009
Variable Frequency Drives (VFD) are commonly used in industrial applications. However, the sensitive components of VFD’s are often susceptible to Power Loss, Power Dips and Brown-Out conditions, which may cause the VFD and the entire system to shut down.
Fortunately there are several solutions for power interruptions. Some VFD manufacturers have incorporated specific algorithms in the software and, with just a few programming changes, the VFD can withstand most of these conditions.
Recently a customer contacted me about a power loss condition which was causing his VFD to drop out. His VFD (which controls his air compressor) had to be restarted each time by issuing a start command separate from the machine it was controlling. The customer asked me if there was anything that I could do to allow his drive to stay powered up during a Power Loss lasting up to three seconds.
Depending on the manufacturer and model of the VFD – and its programming – the drive can store the energy from its capacitor banks for a predetermined amount of time before dropping out and losing power. Think of it this way; if you turn off a VFD, the lights remain on for a few seconds before it is totally powered down. The software can utilize this stored energy to maintain the VFD through a short intermittent Power Loss.
Furthermore, the good news for my customer was that even if it is a long Power Loss, I showed him how to program a second set of parameters in a VFD to restart automatically. Note: starting automatically needs to be analyzed for safety first before programming that function)
I helped my customer reprogram his drive, and his VFD (and his air compressor) is now able to “ride-through” intermittent power losses.
Moral of this story: There are many features available in most VFDs…and I can help you take advantage of these features.
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