48 ● gForce Ultra User Manual 10-2014
7. Variable Speed Compressor
7.1 Features
As the leader in variable capacity compressor technology in the data center industry
responding to environmental and energy challenges, Data Aire developed the gForce
Ultra variable capacity compressor CRAC unit. The compressor technology uses a
brushless Interior Permanent Magnet (IPM) design to provide higher efficiency. And it
delivers efficiency across a wider range. A cooling solution optimized for energy
consumption and for power grid requirements. Thanks to a 4:1 modulation ratio, the
gForce Ultra can cycle from 25 to 100 RPS to provide greater savings.
Match exactly your cooling requirements to control temperature and humidity, critical
for the best process as well as product quality.
7.2 Oil Management
Insufficient oil level can be the result of oil depositing itself in pipes and heat
exchangers. The oil deposit can be returned to the crankcase by increasing velocity for
short periods, at regular time intervals or when the velocity is too low to ensure
adequate oil return.
With oil return management functions that are built into the control system, these two
oil return mechanisms can be programmed in the variable frequency drive (VFD).
With the oil return management function enabled, the VFD performs oil return by
boosting the compressor speed to an appropriate RPM for a selectable duration as
programmed into the VFD parameters. This boost is performed at programmable fixed
time intervals or if the compressor speed has been less than 3000 RPM (50 rps) for too
long which is again a programmable parameter, whichever comes first. Therefore the
maximum time between two consecutive oil return boosts is fully programmable.
Split system unit include an oil separator to allow proper oil return back to the
compressor. This unit still performs the oil management function mentioned above to
ensure oil in long line runs return the oil to the compressor. This is required to ensure
any oil that bypasses the separator is return.
7.3 Crankcase Heaters
A crankcase heater will minimize refrigerant migration caused by the large temperature
gradient between the compressor and the remainder of the systems. When the
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