10-2014 gForce User Manual ● 43
Warning:
Pressure relief lines(s) must be vented to the atmosphere per
the latest edition of ASHRAE Standard 15 and/or any local building, fire or
mechanical codes. This applies to all units with either shell and tube
condensers or high pressure relief valve options.
5.7 Commissioning
The system must be monitored after initial startup for a minimum of 60 minutes to
ensure proper operating characteristics such as:
Proper metering device operation and desired superheat readings
Suction and discharge pressures are within acceptable levels
Correct oil level in compressor sump indicating proper oil return
Low foaming in sight glass and compressor sump temperature 10⁰ F above
saturation temperature to show there is no refrigerant migration taking place
Acceptable cycling rates of compressors, including duration or run times
Short cycling protection is provided in the VFD. It is factory preset “enabled”
with default parameters. The minimum run time is set to ensure long enough
running time at start up in order to create enough refrigerant flow velocity in the
system to recover the oil to the compressor sump.
Current draw of compressor within acceptable values
No abnormal vibration or noise
5.8 Important Refrigeration Components
5.8.1 Variable Capacity Compressor with VFD
The unique feature of the gForce Ultra is the application of variable capacity
compressor. The quest for greater energy efficiency is continuous; efficiency
benchmarks are always moving up. That's why Data Aire is moving toward variable
capacity compressor technology for quieter, more energy-saving performance.
Conventional compressors are designed to run at constant speed to handle a given
capacity requirement. But in data center applications, the capacity requirement varies.
In these situations, a constant speed compressor uses various capacity-regulation
techniques and can be less efficient than a compressor utilizing variable capacity
technology. A variable capacity compressor (VCC), on the other hand, saves energy
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