Data Center Lab · Reference Designs · Electrical
Sheet E201: Cyclic A/B Pairing of 42 Racks Across Six Zone 7 UPS Paths
Six headers walk 42 racks around the six UPS paths so that every path is A for one group of 7 and B for another, and the last header ties UPS7-06 back to UPS7-01.
Design Development — Public Edition P1: a reference design for study and evaluation, not a construction issue, not sealed by an Engineer of Record.
Scroll or pinch to zoom, drag to pan, click a highlighted device for its explanation. Vector drawing — it stays sharp at any magnification.
← E-108 · All electrical sheets · E202 →
What this sheet shows
E201 is the Zone 7 rack diagram. The title reads 42 racks and independent A-B input groups. The subtitle states the rule the rest of the sheet draws: 6 UPS paths, cyclic pairing within Zone 7 only, and two power interfaces per physical rack. Six headers divide the racks, and each header is marked 7 racks. R001 through R007 take A from UPS7-01 and B from UPS7-02. R008 through R014 take A from UPS7-02 and B from UPS7-03. R015 through R021 take A from UPS7-03 and B from UPS7-04. R022 through R028 take A from UPS7-04 and B from UPS7-05. R029 through R035 take A from UPS7-05 and B from UPS7-06. R036 through R042 take A from UPS7-06 and B from UPS7-01. Under each header the sheet draws two horizontal feeders that do not join, the A feeder above the B feeder. Seven rack columns sit on that pair. Each column is one physical rack: INPUT A taps the upper feeder and INPUT B taps the lower feeder.
Design intent you can read off the sheet
Read the six headers down the sheet and each UPS name appears twice, once in an A column and once in a B column. UPS7-01 is A for R001 through R007 and B for R036 through R042. UPS7-02 is B for that first group and A for R008 through R014. UPS7-03 is B for R008 through R014 and A for R015 through R021. UPS7-04 is B for R015 through R021 and A for R022 through R028. UPS7-05 is B for R022 through R028 and A for R029 through R035. UPS7-06 is B for R029 through R035 and A for R036 through R042. No header puts the same UPS on both inputs of the same racks. The two feeders under a header never join. That is the same statement as the design-basis note: each rack has two independent input groups, each group supports the specified surviving-side duty, and no UPS AC outputs are tied together. The racks that list a given UPS are two groups of 7, one where it is the A source and one where it is the B source. Those racks still have the other input, and that other input names a different UPS. The groups that do not list the path are not on it. The subtitle keeps the cycle within Zone 7. The wrap is the word cyclic: without R036 through R042, UPS7-01 would appear only as an A source and UPS7-06 only as a B source. How an unparalleled UPS output sets the failure domain is discussed in the electrical architecture notes.
Tags, rating basis, and what is still open
The branch tag is RCB, then the rack, then A or B. At the first rack that is RCB-R001-A over R001-A, INPUT A, and RCB-R001-B over R001-B, INPUT B, and the block is marked OCP function. The same pair is drawn at every rack through R042. The note under the diagram says what those tags are, and what they are not yet. RCB tags denote branch protection functions, and final branch and whip quantity, current and poles follow the server OEM input architecture. That selection is open on the sheet. The same note says cross-sheet references identify the associated circuits. Each feeder callout is that reference: the UPS name, the words from E107, and a Z7-OUT tag of the same index, from Z7-OUT-01 beside UPS7-01 to Z7-OUT-06 beside UPS7-06. Upstream of the callout, the path is not redrawn here. The rating note prints two different rack figures and labels the job of each. 136 kW/rack is the comparison figure. 155 kW/rack is the screening figure. Concurrent rack loading shall include actual CDU package loads within zone and path capacities. No CDU kilowatt is printed. The surviving-side duty named in the design-basis note is not given a kilowatt on this drawing either. A reader who takes 136 kW/rack as the entire electrical load of the rack has skipped the screening figure and the CDU sentence.
Status
The title block reads Design Development — Public Edition P1 / 2026-09. This is a reference design for study and evaluation, published with its assumptions and open items on the sheet. The pairing is drawn in full: six groups, 7 racks in each, two interfaces on every rack from R001 to R042, cyclic inside Zone 7, with the UPS AC outputs not tied. What the sheet does not close is the branch device, and the load arithmetic past the two named bases. Quantity, current and poles of the branch and the whip wait on the server OEM input architecture. The 136 kW/rack comparison, the 155 kW/rack screening, and the instruction to include CDU package loads are the rating basis, not a filled load schedule.
Sheet guide — the devices on this drawing
E201 title — cyclic pairing inside Zone 7
The drawing title fixes the subject: Zone 7, 42 racks, independent A-B input groups. The subtitle is the pairing rule itself: 6 UPS paths, cyclic pairing within Zone 7 only, and two power interfaces per physical rack. Everything below that line is the rule drawn out.
R001–R007 — A: UPS7-01, B: UPS7-02
The first header assigns R001 through R007, marked 7 racks, with A on UPS7-01 and B on UPS7-02. The upper feeder is the A path and the lower feeder is the B path, and each of these racks takes both. This is the start of the cycle, not one A bus and one B bus for the whole zone.
UPS7-01 / UPS7-02 — from E107, Z7-OUT
The left of each feeder names the UPS, notes that it is from E107, and carries a Z7-OUT tag of the same index: Z7-OUT-01 on the UPS7-01 feeder and Z7-OUT-02 on the UPS7-02 feeder. The one-line upstream of that callout is not redrawn on this sheet. The note below says cross-sheet references identify the associated circuits.
R001 — INPUT A and INPUT B
R001 is one physical rack with two interfaces on two feeders. The upper block is RCB-R001-A, marked OCP function, and lands on R001-A, INPUT A, from UPS7-01. The lower block is RCB-R001-B, INPUT B, from UPS7-02. The two blocks do not share a bus.
R007 — seventh rack on the first feeders
R007 closes the first group. It is still one rack, with RCB-R007-A on the UPS7-01 feeder and RCB-R007-B on the UPS7-02 feeder, labeled INPUT A and INPUT B. The header's count of 7 racks is drawn across the sheet, through this last column.
R008–R014 — A: UPS7-02, B: UPS7-03
The second header steps both sources forward. A is UPS7-02, which was the B source for R001 through R007, and B is UPS7-03. Racks R008 through R014 are again marked 7 racks. One UPS name serving one group as B and the next group as A is the handoff the cycle is built from.
R022–R028 — A: UPS7-04, B: UPS7-05
Mid-sheet the step has not changed shape. R022 through R028 are marked 7 racks, A from UPS7-04 and B from UPS7-05. UPS7-04 is also the B source on the header above, R015 through R021, whose A source is UPS7-03. The pairs keep moving. They do not settle into one fixed A side and one fixed B side for the hall.
R036–R042 — A: UPS7-06, B: UPS7-01
The last header is what makes the pairing a cycle. R036 through R042, marked 7 racks, take A from UPS7-06 and B from UPS7-01. UPS7-01, which opened the sheet as an A source, returns here as a B source, and it returns inside Zone 7. No header on this sheet names a path outside the six.
R042 — last rack, two interfaces
R042 is the last physical rack on the sheet, and it is still two interfaces rather than a remainder on a single path. RCB-R042-A, INPUT A, is on the UPS7-06 feeder. RCB-R042-B, INPUT B, is on the UPS7-01 feeder. The wrap is drawn at the rack, not only written in the header.
Sheet notes — duty, 136 and 155 kW/rack, RCB open
Three notes sit under the diagram. Each rack has two independent input groups, each group supports the specified surviving-side duty, and no UPS AC outputs are tied together. The rating line gives 136 kW/rack for comparison and 155 kW/rack for screening, and concurrent rack loading includes actual CDU package loads within zone and path capacities. RCB tags denote branch protection functions; final branch and whip quantity, current and poles follow the server OEM input architecture.
Get the full drawing set
This sheet is one page of the Electrical Drawing Book — Public Edition P1 (88 pages, 14 MB) — a direct PDF download with a published SHA-256 checksum, no registration. The complete coordinated set is on the downloads page. Background guides: data center one-line diagrams · GB300 NVL72 facility requirements · liquid cooling and CDU design.
Questions about any device or parameter on this sheet: inquiry@kkdatasvc.com or the contact page.