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Variable Speed Fire Pump Controllers were invented and released with a UL Listing for fire pump service in 2003 by Master Control Systems, Inc. [1] [2] Paragraph 10.5.5 in the 2003 edition of NFPA-20 recognized Variable Speed as an accepted method for operating the fire pump. Then in the NFPA-20 2007 edition, section 10.10 was added to clarify ...
A common type of variable-displacement pump used in vehicle technology is the axial piston pump. This pump has several pistons in cylinders arranged parallel to each other and rotating around a central shaft. A swashplate at one end is connected to the pistons. As the pistons rotate, the angle of the plate causes them to move in and out of ...
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 ...
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 ...
The basic function of a pump is to do work on a liquid. It can be used to transport and compress a liquid. In industries heavy-duty pumps are used to move water, chemicals, slurry, food, oil and so on. Depending on their action, pumps are classified into two types — Centrifugal Pumps and Positive Displacement Pumps. While centrifugal pumps ...
Specific speed N s, is used to characterize turbomachinery speed. [1] Common commercial and industrial practices use dimensioned versions which are of equal utility. Specific speed is most commonly used in pump applications to define the suction specific speed —a quasi non-dimensional number that categorizes pump impellers as to their type and proportions.
In order to produce the proper voltage at a constant AC frequency, usually three-phase 115 VAC at 400 Hz, an alternator needs to spin at a constant specific speed (typically 6,000 RPM for air-cooled generators). [1] Since the jet engine gearbox speed varies from idle to full power, this creates the need for a constant speed drive (CSD).
A constant-speed propeller is a variable-pitch propeller that automatically changes its blade pitch in order to maintain a chosen rotational speed, regardless of the operational conditions of the aircraft. This is achieved by use of a constant-speed unit (CSU) or propeller governor, which automatically changes the propeller's blade pitch.