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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 ...
With a variable-speed drive on the pump or fan, the supply can be adjusted to match demand and no extra loss is introduced. For example, when a fan is driven directly by a fixed-speed motor, the airflow is designed for the maximum demand of the system, and so will usually be higher than it needs to be.
This article is a subtype of variable speed drive, of which there are many beyond just electronic means. That DoE PDF says this right in the 2nd paragraph of the first page: Speed can be controlled in a number of ways, with the most popular type of variable speed drive (VSD) being the variable frequency drive (VFD).
N 2 chart example. [1] The N 2 chart or N 2 diagram (pronounced "en-two" or "en-squared") is a chart or diagram in the shape of a matrix, representing functional or physical interfaces between system elements. It is used to systematically identify, define, tabulate, design, and analyze functional and physical interfaces.
VSD may refer to: .vsd, a file extension for Microsoft Visio diagrams; VSD (French magazine) (Vendredi Samedi Dimanche; i.e. "Friday Saturday Sunday"), a French weekly news magazine; Vaccine Safety Datalink, a Centers for Disease Control database containing vaccination and health records of over 7 million Americans
In telecommunications, an eye pattern, also known as an eye diagram, is an oscilloscope display in which a digital signal from a receiver is repetitively sampled and applied to the vertical input (y-axis), while the data rate is used to trigger the horizontal sweep (x-axis). It is so called because, for several types of coding, the pattern ...
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An eye chart is a chart used to measure visual acuity comprising lines of optotypes in ranges of sizes. Optotypes are the letters or symbols shown on an eye chart. [ 1 ] Eye charts are often used by health care professionals, such as optometrists , physicians and nurses , to screen persons for vision impairment .