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Small variable-frequency drive Chassis of above VFD (cover removed). A variable-frequency drive (VFD, or adjustable-frequency drive, adjustable-speed drive, variable-speed drive, AC drive, micro drive, inverter drive, variable voltage variable frequency drive, or drive) is a type of AC motor drive (system incorporating a motor) that controls speed and torque by varying the frequency of the ...
Fan assemblies with this control input provide the ability to adjust the rotational speed of the fan without changing the input voltage delivered to the cooling fan assembly. A variable rotation speed allows the cooling rate to be adjusted to meet demand, quietening the fan and saving energy when full speed is not required.
Where noise is an issue, larger, slower-turning fans are quieter than smaller, faster fans that can move the same airflow. Fan noise has been found to be roughly proportional to the fifth power of fan speed; halving the speed reduces the noise by about 15 dB. [22] Axial fans may rotate at speeds of up to around 38,000 rpm for smaller sizes. [23]
A High-volume low-speed fan. A high-volume low-speed (HVLS) fan is a type of mechanical fan greater than 7 feet (2.1 m) in diameter. [1] HVLS fans are generally ceiling fans although some are pole mounted. HVLS fans move slowly and distribute large amounts of air at low rotational speed– hence the name "high volume, low speed."
Speed feedback is typically provided via an integral AC tachometer. Eddy current drives are slip-controlled systems the slip energy of which is necessarily all dissipated as heat. Such drives are therefore generally less efficient than AC/DC-AC conversion based drives. The motor develops the torque required by the load and operates at full speed.
A vacuum fluorescent display (VFD) is a display device once commonly used on consumer electronics equipment such as video cassette recorders, car radios, and microwave ovens. A VFD operates on the principle of cathodoluminescence , roughly similar to a cathode-ray tube , but operating at much lower voltages.
Thus it is not possible to control the motor if the output frequency of the variable frequency drive is zero. However, by careful design of the control system it is possible to have the minimum frequency in the range 0.5 Hz to 1 Hz that is enough to make possible to start an induction motor with full torque from a standstill situation. A ...
If a variable speed drive compressor operates continuously at full speed, the switching losses of the frequency converter result in a lower energy efficiency than an otherwise identically sized fixed speed compressor. Where demand remains constant within 5–15% of the total free air delivery flow rate, dual-control compressors configured in a ...