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 With the integration of the motor, VSD, and magnetic-bearing system, the capacitors required for the motor and drive can be used as a backup power source for the bearings in the event of a power outage or emergency shutdown.CAPACITY AND EFFICIENCYAmong the key parameters affecting performance are capacity (tons) and efficiency (kilowatts per ton). The compressor''s capacity ranges from 60 to 90 tons, depending on the operating conditions. Plans call for that range to be extended to 150 tons water-cooled and 115 tons air-cooled by the end of 2004 with the use of R-134a refrigerant. An R-22 version is planned for retrofit applications.Efficiency improvements stem from a combination of the centrifugal compressor, permanent-magnet motor, and magnetic bearings. Within the compressor, efficiency is affected by the compressor isentropic efficiency (the efficiency of the wheels), the motor, and the bearings. Traditional induction motors of this size typically are in the 92-percent efficiency range. This compressor''s permanent-magnet motor has an efficiency of 96 to 97 percent. THE MOTORMost hermetic compressors use induction motors cooled gasaircompressorsskidmounted by either liquid or suction-gas refrigerant. Induction motors have copper windings that, when alternating current gasaircompressorsskidmounted is run through them, create the magnetic fields that cause the motor to turn. These copper windings are bulky, adding size and weight to the compressor.Two-pole, 60-Hz induction motors operate at approximately gasaircompressorsskidmounted 3,600 gasaircompressorsskidmounted rpm. A higher number of revolutions per minute can be obtained by increasing the frequency. Compressors that require higher shaft speeds tend to use gears. While gears are a proven technology, they create noise and vibration, consume power, and require lubrication.The magnet-bearing compressor features a synchronous permanent-magnet brushless DC motor with a completely integrated variable-frequency drive (VFD). The stator windings found on conventional induction motors are replaced with a permanent-magnet rotor. Alternating current from the inverter energizes the armature windings. The stator (excitation) and rotor (armature) change places. No commutator brushes are required. The motor and key electronic components are internally refrigerant-cooled, so no special cooling is required for the VFD or the motor. NITROGEN GENERATORSNitrogen generators use either membrane or pressure-swing-adsorption (PSA) technologies. Membrane generators made by Balston, a division of Parker, produce up to 99.5% pure, commercially sterile nitrogen at dewpoints to -58[degrees]F from compressed air. They use proprietary membrane-separation technology to divide air into two streams: one 95 to 99.5% pure nitrogen, the other oxygen-rich with carbon dioxide and other trace gases.Compressed air flows gasaircompressorsskidmounted through bundles of individual, hollow fibers made of semipermeable membranes. Each fiber has a perfectly circular cross section and a uniform bore through its center. Because the fibers are so small, a great many can be packed into a limited space, providing enough surface area to produce a relatively high-volume flow of nitrogen. Buy a gas air compressor with us and save a TON of cash. Our selection of cheap gas air compressors is second to none.
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