Quiz: AI Data Center Electrical Infrastructure (Part 4)

10 questions from Part 4 of the guide. Score instantly; every explanation links to the chapter that derives the answer.

How many functional conversion packages does the guide’s stated AC fixture count through final DC conversion?
91534
ABB’s low-harmonic drive comparison reports what at nominal load, and what can an AI-hall designer conclude?
~15% THD — same as legacy servers<5% THD for the named drive; qualify the server spectrum, transformer heating and synchronized load step separately~30% THD — evaluate the measured spectrum, thermal capacity/K-factor, and harmonic-current mitigationTHD is no longer measurable at these power levels
Why does the 13th harmonic matter so much more than the 5th for transformer heating?
it carries more currentit trips protective relays firstit resonates with the grid frequencyat equal RMS current, winding eddy-current loss scales with h²: 13th ≈ 169× the fundamental vs ~25× for the 5th
Moving row distribution from 208 V to 415 V three-phase does what to rack power per ampere?
No change — voltage doesn't matterHalves itRoughly doubles itQuadruples it
NVIDIA has quoted both '~85%' and '+157%' more power through the same copper for 800 VDC vs 415 VAC. Why do both figures exist?
They compare different conductor topologies — the +157% counts a three-wire DC feed (POS/RTN/PE) against four-conductor AC; the comparison basis changed, not the physicsThey refer to different rack generationsThe +157% superseded the ~85% after a hardware revisionOne is marketing and one is measured
A rack can still be served by either a conventional AC chain or a rack-scale DC architecture. What decides when the project should cross over?
the rack vendor's preferred labelthe highest voltage the utility offersa route-specific calculation of deliverable current, protection frames, conductor count and loss, conversion efficiency, and service constraintsa universal rack-power threshold
The solid-state transformer (SST) matters because it…
removes the transformer lead-time problemintegrates MV-to-DC functions in one package whose efficiency, isolation, fault behavior and service interface must qualify at the same output boundaryeliminates the need for a substationis cheaper than a conventional transformer today
What UL ratings do Eaton's and Starline's current track-busway lines offer?
A single fixed 800 A rating250–1,200 A across the two linesUp to 400 A only5,000 A trunk lines
Which two independent duties must AI-hall storage qualify?
reserved outage continuity plus repetitive load smoothing, including recharge and residual bus responselong-duration storage for demand response onlypure surge suppressionit is being removed entirely
What does choosing 48 V for an OCP in-rack bus establish — and what does it not establish?
a nominal voltage input to equipment qualification; SELV/PELV also depends on isolation and installation conditions, while arc, short-circuit and stored-energy duties remain48 V minimizes copper masshigher voltages don't exist in DC partsit matches telecom heritage only

Check your understanding: Electrical & Energy Infrastructure