An AC drive is a device used to control the speed of an electrical motor in order to: 

• Enhance process control 
• Reduce energy usage and generate energy efficiently
• Decrease mechanical stress on motor control applications
• Optimize the operation of various applications relying on electric motors

Drives can also be utilized to convert energy from natural and renewable resources like the sun, wind or tides, and transmit it to the electrical network or use it for local consumption. In hybrid technologies, AC drives are used to combine conventional energy sources and energy storages to create total energy management solutions.
AC drives are also known by various other names such as adjustable speed drives, adjustable frequency drives, variable frequency drives, variable speed drives, frequency converters, inverters and power converters.

Did you know?

• Emerging economies are driving the increase in energy consumption
• 20% of the world’s energy consumption is electrical energy
• 40% of electrical energy is used by electrical motors
• 75% of AC drives are used on pumps and fans
• Global electrical energy consumption could be reduced by 10% if AC drives were used in every suitable application

Contact our Danfoss factory trained team can help you analyze your processes and help you determine the right drive. To learn more about Danfoss, click here.

Decatur Industrial Electric and TECO-Westinghouse announce distributorship appointment! Trent Thompson, President of Decatur Industrial Electric stated that; “TECO-Westinghouse is an industry brand that has great recognition in heavy industrial industries and their product line is outstanding. They bring us a diversified portfolio that complement our current industry leading vendor partners to bring our customers reliable and efficient solutions. We look forward to working with their team!”

About TECO-Westinghouse – www.tecowestinghouse.com
With over 100 years of experience in motor design and application, the Company is a premier supplier of AC and DC motors and generators. Ranging from fractional hp ratings to 100,000 hp, these high-quality machines are used to drive pumps, fans, compressors, rolling mills, grinders, crushers, and a variety of other rugged applications. Their motors and generators are utilized in petroleum, chemical, pulp, paper, mining, marine propulsion, steel, electric utility and other industries throughout the world.  TECO and Westinghouse Electric established a joint venture relationship in 1988 and TECO purchased Westinghouse in 1995. Today, TWMC is in a unique position of being able to provide quality motors, generators, drives, and power solutions, all from our headquarters in Round Rock, Texas. This capability, combined with our global manufacturing resources, uniquely position the TECO-Westinghouse Motor Company to serve all our customer needs.

DC motors are relatively simple machines consisting of an armature winding (rotating) and shunt/series windings (stationary). Energizing these two primary components of the DC motor creates two magnetic fields that push or pull each other to make the armature rotate. Recording a winding resistance value on these components is a common practice during de-energized motor testing for trending or troubleshooting. When it comes to measuring winding resistance, remember our tip that smaller is bigger. The smaller the wire size the bigger the resistance. The rotating armature windings, connected to the commutator, are relatively large and in many industrial DC motors are form wound. The stationary series windings are randomly wound around the pole pieces and are also relatively large. By relatively large we mean that if you look at an individual strand of copper wire that makes up the armature or series winding, the diameter or circular mils of the strand is larger when compared to the shunt field windings. The shunt field windings are also randomly wound around the same pole piece as the series winding but consist of much smaller strands of wire when compared to the series and armature windings. Therefore, true to our tip, on smaller shunt field windings you would expect a bigger resistance reading. Having a basic understanding of these two components will make you more effective when analyzing the data received when performing a winding resistance test on a DC motor. To learn more from PdMA about motor analysis and troubleshooting, click here.

Resonance is a condition that can occur in mechanical structures and can be described as sensitivity to a certain vibration frequency. Resonance occurs when a natural frequency is at or close to a forcing frequency, such as rotor speed. For machinery—such as pumps, turbines and electric motors—resonance can amplify the small vibratory forces from machine operation, and severe vibration levels can result. Such problems often develop after a speed change has been implemented, as with retrofitting a machine with an adjustable-speed drive (ASD) or operating a 50-hertz motor on 60 hertz of power.

The solution to these problems frequently depends on distinguishing between structural resonance and a rotor critical speed. Structural resonance refers to excessive vibrations of non-rotating components, usually machine components or supporting structures. Rotor critical speed refers to a condition in which the speed of the rotating element of the machine matches the rotor’s natural frequency

Many of you have good in-house predictive maintenance departments, and others outsource that work to others. Either way, you routinely know when a bearing is deteriorating, and remove the motor from service before it turns into a catastrophic failure. That saves a lot of maintenance dollars, which is great. But if you stop there — without discovering why that bearing is faulty — you could be facing the same problem again in a few short weeks or months. Bad bearings often hold a great deal of evidence, if you know what items to focus on.  Click here to learn more and read the complete article.

From Electrical Construction & Maintenance Magazine

By Chuck Young, Senior Technical Support Specialist, Electrical Apparatus Service Association