Technical Requirements -
Computer Room
The UPS shall be UL listed and labeled (or equal) for use in a computer room in
accordance with the National Electrical Code.
1. Oversized neutrals and wiring of ADP equipment
All isolated circuits feeding ADP equipment shall be installed with oversized
neutrals to reduce neutral heating. Neutrals shall have current ratings of at least
1.7x phase rating to achieve these results. A ground wire should be pulled for
each circuit along with a dedicated neutral (for each 3 phase feed.) The
transformers shall be sized, installed, and protected per manufacturer's
recommendations and Code requirements and allowance will be designed in for
30% additional capacity. PDUs/power distribution panels shall have a minimum
of 30% spare, 3-pole breaker positions with a proportional number of single, two
phase and three phase spare breakers.
2. Emergency Generators/Automatic Transfer Switches/Emergency backup
power:
Emergency generators should be considered for Sector Sites and offices that
have VBA wide data processing duties in order to preclude potentially wide
ranging disruption of services and benefits payments for power outages longer
than 20 minutes. Generators may be justified on a case by case basis
depending upon the reliability of local utilities and potential for natural disasters
knocking out electric service to the facility (this must be justified by the local
office.) The size of backup battery systems on the UPS, telephone switch and
other systems can be reduced if generators are installed to backup these
systems
In cases where generators are justified, emergency power shall be provided for
the following: life safety, computer room UPS, telephone equipment rooms,
generator room, and other essential lighting as determined by the design team;
security, fire, smoke and water detection systems; computer room and main
telephone equipment room A/C systems; UPS system; all automatic
temperature control systems, including pneumatic air compressors, air dryers,
local and central engineering controls; and critical ventilation equipment.
The UPS system Automatic Transfer Switch (ATS) shall be of the "delayed
transition type," precluding an engine start during short power interruptions that
can be accommodated by the UPS battery (generally set for 50-60 seconds.)
Upon loss of phase voltage to the ATS, a start signal will be sent to the
emergency generator(s) and a transfer to emergency power will occur when
conditions are met. For other loads powered by the emergency generators,
VBA Design Guide
Page 4-7
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