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How to select a VSD
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This material aims as a guide to give an indication of how to select Variable Speed Drives (VSDs) from the Schneider Electric catalogue. This may not be your last point of guide, but it should give an idea of where to start.
VSDs are frequency-varying systems that are used in the power electronics space as motor starters. There are different functions that these machines can be used for, even the type of industry they serve. VSDs were first developed in the late 1950s when there was a growing need to conserve energy and use it efficiently. The technology gained popularity when improvements and technological advances were introduced, since the first units were very bulky and expensive [1]. Today they can be seen in most infrastructures, from pump applications, HVAC applications, conveyer applications and many other related controls.
For this article, only the Low Voltage (LV) VSD ranges will be discussed. There are two main sub-categories that we use to distinguish our main Altivar (ATV) offers. ATV900 and ATV600 , the control that sets the two units apart is based in their application. The built-in functions within the drive make it redundant to select the drive without drilling into the built-in functions inside the drive. For demanding applications such as hoisting, lifts, braking and other high torque controls, we recommend the ATV900. The ATV600 is more suitable for the pump, water, and wastewater applications. Figure 1 details the built-in functions for the two drives.
The drives have dual rating setting, Normal Duty (ND) and Heavy Duty (HD), to handle overloading capabilities. For a drive rated 120%, this drive can deliver 20% overload past nominal. For motor applications with high starting current, the drive can be overloaded by 150%(HD) for the first cycles, once the motor reaches synchronous speed, the drive overload capability can be changed to ND. The important part to note is the current limitation when the drive is loaded at HD; therefore derating must be taken into consideration when making a decision.
Both units can be wall mounted, floor standing systems and modular drives LV for cabinet integration. Floor standing systems can be categorized into three designs, Customized To Order (CTO), Engineered To Order (ETO) and Design To Order (DTO). CTO are standard cubicles with standard options such as push buttons. ETO are standard cubicles with customer-specific options such as painting and additional standard options that can be found in CTO designs. DTO are cubicles with specific designs with specific options. All of our VSD products are also green premium label certified.
Reference material
[1] D. Roethemeye and D. Yankaskas, "EVOLUTION OF MOTOR AND VARIABLE FREQUENCY DRIVE," in ACEE, St. Louis,Missouri, 1995.
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