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Direct Current (DC) Power Systems

DC power systems that serve critical loads are common in two forms:

  • The primary power source for access provider and carrier equipment.
  • As an alternative to AC power in computer rooms because of energy efficiency, design simplification and ease of paralleling alternative energy sources DC power distribution systems function within the data center in the same way as the AC systems providing power to a variety of loads. However, DC-based systems can offer additional features that can be attractive to data center designers and operators. It is also possible to mix DC and AC systems in hybrid configurations, for example, providing DC to critical loads and AC to mechanical loads.

DC power system operating voltages are affected by several factors such as:

  • Battery technology (e.g., lead-acid varieties, nickel-cadmium, nickel-metal-hydride, lithium-ion varieties, sodium varieties, flow varieties)
  • Rectifier output regulation in maintaining constant voltage under dynamic loads
  • Voltage drops in DC power conductors—cable sizes and lengths
  • Operating voltage limits of various connected loads
  • Derating for environmental conditions such as altitude
  • All DC equipment shall be properly and clearly marked according to the applicable electrical or building codes and as required by the appropriate listing agency. DC equipment includes, but is not limited to:
  • Cords
  • Cables
  • Raceways
  • Bus ways
  • Power connectors
  • Junction boxes

 

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