Worldwide, AC motors account for roughly 25% of the total energy consumption. Of that 25% about 3% are controlled by Variable Frequency Drives (VFDs). VFDs drastically increase energy efficiency of processes that utilize AC motors; specifically variable torque loads such as fans and pumps. Proper application of VFDs have the potential to, globally, save millions of kilowatts of energy per year which in turn reduces emissions from fossil fuel power plants. VFDs make green energy. For example Siemens Medium Voltage Perfect Harmony drives, since their invention in 1994, have saved the equivalent CO2 emissions as cars driven 1,294,385,734,286 miles per year or saved the energy equivalent to 74,778,818 U.S. homes usage for one year. Imagine if we could tap into the 97% of these AC motors that are controlled by VFDs. The benefit to humanity would be significant.
Medium voltage drives are traditionally used for applications larger than 500 HP or for applications which require very long cable runs (>2000’) between the VFD and the motor. Medium voltage drives have superior reliability over their low voltage counterparts and are primarily used in applications which require very long Mean Time Between Failures (MTBF). Medium voltage drives also have very low Total Cost of Ownership (TCO) over the lifespan of the drive. All these factors combine result in a quick Return On Investment (ROI) for end users and globally reduced emissions and reliance on fossil fuels.
Topology of the medium voltage drives vary greatly, from Current Source Inverters (CSI) to Voltage Source Inverters. With the advent of Isolated Gate Bipolar Transistors (IGBTs) in the early 1980’s VFD technology has become widely available. However with the varied range of topologies selecting the appropriate VFD for an application is critical to realize the MTBF, TCO, and ROI the customer is expecting. An experienced engineering firm can manage these topologies and select the best VFD for a given application.