As we’ve discussed before, the main components of a variable frequency drive (VFD) are a rectifier (also referred to as a converter), which converts AC voltage to DC voltage, a DC bus (also referred to as a DC link), which filters and stores the DC power, and an inverter, which converts the DC power back to […]
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What are VFD reflected waves and why are they harmful?
Reflected waves, also known as transmission line effects or standing waves, are over-voltages that can damage the motor and cable. The use of IGBTs (insulated gate bipolar transistors) in variable frequency drives has helped to improve VFD performance in several ways. First, their quick switching time (also referred to as rise time, or dV/dt) means […]
FAQ: What is a VFD line reactor?
Many of the components that make up a variable frequency drive (VFD) are semiconductor components, which are sensitive to power or current surges, voltage spikes, line distortion, and general power anomalies. A line reactor is an optional component that can be added to a drive system to protect the VFD and other devices from power […]
What is a rectifier?
AC motors can be operated directly from AC supply voltage, but this is only suitable if the motor is required to run at constant speed. If the speed or load requirements of the motor change, an AC drive — also referred to as a variable frequency drive (VFD) — can vary the voltage and frequency […]
New VFDs offer quick, easy setup
The new ACF Series from American Control Electronics is an open chassis microprocessor-based variable frequency drive (VFD) that offers the simplicity of a DC drive. ACF700 drives are designed for quick and easy setup without any programming, in contrast to the complex programming associated with standard VFDs. The drives are equipped with user-adjustable trim pots […]
Self-protected combination motor controllers from Sprecher + Schuh
The new Series KTV7 Multi-Motor Controllers are the newest addition to Sprecher + Schuh’s KT7 family of motor controllers. The KTV7 series of self-protected combination motor controllers are ideal for use with variable frequency drives (VFDs) in multi-motor installations for industries that include food and beverage, material handling and factory automation. Designed for use with […]
FAQ: What are the different ways that industry classifies servo motors?
A servo system is one in which the system’s error (in position, speed, or torque) is corrected through the use of a feedback device that compares the system’s actual performance with its commanded performance. What makes a motor a servo motor, then, has less to do with its construction and operation, and more to do […]
Eaton VFDs keep North Carolina town’s water flowing
A custom variable frequency drive (VFD) from Eaton was recently installed at the Town of Mooresville’s Water Treatment Plant in Mooresville, North Carolina. The VFD fits within the plant’s space constraints and has been keeping its 800-hp pumps moving efficiently. To avoid redundancy between the town’s new and old plants, and to maintain usability of […]
More motor rating choices thanks to NovaTorque 2400 rpm motor
NovaTorque, Inc. has introduced 2400 rpm versions of its 3hp through 15hp models, with rated efficiencies of 93.5 to 95%. Until now, when the desired operating point of a fan fell in the 2200 to 3200 rpm range, the designer was left with less than optimum choices. One could over-speed a 4 pole 1800 rpm […]
How to handle imbalances from light loads on VFDs
by Daniel Peters, Drives Application Engineer, Yaskawa America Input current imbalances happen when a variable frequency drive (VFD) with a full-bridge rectifier operates under lightly loaded conditions. Here we explain what to do about it. One phenomenon that electricians often see after installing a VFD is measurable current imbalance on the input to the VFD […]