K&K Data Service Inc.Data Center Engineering Lab

Data Center Lab

Electrical Architecture and Failure Domains

This series publishes working engineering analysis from K&K's data center program. Numbers are labeled [TARGET], [MODELED], [SENSITIVITY] or [FACT]; nothing here is field-measured data, and no article is a sealed engineering document. Each article states its own limits and open items.

K&K drawing V336-E-110: four-path power one-line from a shared utility point of interconnection through transformers, ATS and UPS to PDU paths
K&K program drawing V336-E-110: four-path power to aggregate loads (study revision — not released for construction).
  1. KK-DCL-001Two Feeders, One Substation: That Is Not Utility 2NBoth 12.47 kV feeders originate at the same substation, so the shared substation event deletes the nominal utility redundancy the one-line implies.
  2. KK-DCL-002Even Facility-Load Split Exceeds the 7 MW Feeder AllocationAn even normal-load split puts the 7 MW feeder over its limit by about 0.196 MW, so mechanical and house load must be biased to the 8 MW side.
  3. KK-DCL-003Single-Feeder Loss Is a Generation Event, Not a Utility TransferNeither surviving feeder carries the whole plant, so single-feeder loss is not a transfer event but an entry condition for controlled generation or load shed.
  4. KK-DCL-004UPS Sizing Follows Protected Load, Not the 12 MW Sales NumberUPS sizing follows the 12.711 MW protected-load figure that includes CDU and end-of-path losses, not the 12 MW billable IT headline.
  5. KK-DCL-005A Single 480 V Campus Bus Would Be 15,443 ACollapsing the campus onto one 480 V bus produces a current magnitude that the bracing, SCCR and arc-flash chain cannot absorb at concept stage.
  6. KK-DCL-006Each Dual-Cord Path Must Be Sized for Full Rack LoadEach cord of a dual-cord rack must carry full load under single-path operation, so conductor sizing does not halve when the second path is added.
  7. KK-DCL-007The 15 MW Service Cap and the 125% Conductor Rule Are Different LimitsThe 15 MW service cap and the continuous-load derating requirement are separate constraints that are frequently collapsed into one number.
  8. KK-DCL-008Matching MV Bus Identity to LV A/B Deletes Both Redundant PathsMedium-voltage bus ownership must be decoupled from the low-voltage A/B redundancy path or a single MV event erases nominal redundancy.
  9. KK-DCL-009Do Not Map Electrical Systems 1:1 onto Cooling ZonesAligning electrical failure domains one-for-one with cooling zones creates a coupled domain that fails both systems on a single event.
  10. KK-DCL-010Billable IT, Protected Load, Facility Load, and Service Cap DifferBillable IT, protected load, facility load and service cap are four different denominators that must be drawn on the same sheet to stop silent substitution.
  11. KK-DCL-011A 4 MW Zone Block Is 4,000 Billable, 4,237 Protected, 4,797 FacilityThe block named for 4 MW carries three different power figures — 4,000 kW billable, 4,237 kW protected and 4,797 kW facility — and only the first is a round number.
  12. KK-DCL-0128 MW and 7 MW Feeder Losses Leave Different Generation ShortfallsPath A and path B carry different mechanical and house allocations, so the two single-path failure cases are not mirror images.