By Jeff Shepard Contributed By DigiKey's North American Editors
International Electrotechnical Commission (IEC) standard 61800 recognizes two types of adjustable speed electrical power drive systems (PDS) for industrial applications. 61800-1 applies to direct current (DC) PDS, and 61800- 2 applies to alternating current (AC) PDS. The term PDS applies to the entire system of drive plus motor. Other sections of 61800 discuss test methods, safety requirements related to thermal and energy conditions, functional safety, electrical and environmental requirements for encoders, electrical interfaces, and performance measurements. The newest part, IEC 61800-9, covers ecodesign for motor systems, including energy efficiency determination and classification. While IEC 61800 defines adjustable speed AC and DC PDS, there are also general definitions for variable speed drives (VSDs) and variable frequency drives (VFDs) in industrial applications. IEC 61800 applies to mains-powered PDS connected to up to 1.5 kV AC 50 Hz or 60 Hz. It also applies to DC input voltages for battery-powered systems like industrial autonomous mobile robots (AMRs) that use adjustable speed drives. Traction and electric vehicle drives are excluded from IEC 61800.
This article briefly presents the common definitions of VSDs and VFDs and looks at why VFDs are widely used. It then reviews the efficiency classes defined in IEC 61800-9 for AC drives and, considers exemplary mains-powered VFDs from Delta Electronics, Siemens, Schneider Electric, Omron Automation , and closes by looking at the use of VFDs in AMRs and other battery- powered systems using an example system from MEAN WELL . The standard definition of a VFD is a drive that uses changes in frequency to control motor speed, making them useful with AC motors. At the same time, a VSD varies the voltage to control the motor, making it useful for both AC and DC motors. But it’s not quite that simple. Both types of drives can be used to control the speed of motors. As a result, sometimes, the term VSD is applied to VFDs. VFDs can be used with brushless DC motors (BLDCs); strictly speaking, they are not limited to AC motors. VFDs are suitable for use with a variety of motors like: ■ Induction (IM), or asynchronous AC motors, are widely used in industrial applications since they are self-starting, reliable, and economical.
we get technical
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