Requirements/Considerations of Next Generation ORv3 PSU and Power Shelves (OCP EMEA Summit 2025)

Overview

This joint Delta and Advanced Energy talk by Cihan Aydin and Harry Soin, given at OCP EMEA Summit 2025 in Dublin (DC Physical Infrastructure track), compares ORv3, ORv3 HPR and HPR2 power supply units and shelves. It tabulates input range, output, efficiency and size, explains the new AC-loss signalling used to hand over to battery backup units (BBUs), and describes pulse-load requirements driven by AI GPUs.

HPR and HPR2 PSUs both accept 180-305 VAC and reach 97.5% peak and 96.5% full-load efficiency including fans. HPR2 doubles output to 49 V/244 A but derates operating ambient to 35 C (HPR: 45 C). Shelf power rises from 33 kW to 72 kW within the same outer dimensions. The ORv3 1OU shelf has six 5.5 kW rectifiers: 33 kW at N+0 or 27.5 kW at N+1, 50 V, 600 A nominal, 20 ms hold-up.

BBU handover is now triggered by an AC_LOSS signal: the BBU starts within 4 ms (bus below 48.5 V for 2 ms plus 2 ms start-up) and can run up to 240 s; PSU hold-up energy is 60 J for loads up to 150%. The pulse-load requirement has been updated for AI GPUs to 160%/136% of rating.

Bench results show power factor and current distortion under dynamic loads: at 277 VAC with 15-160% dynamic load, the PSU measured PF 0.998 and iTHD 2.91%. With the input limit set to 4.5 kW, a peak to 5.5 kW lasting over 100 ms shut the unit down unless auto-adjust raised the limit. A peak-shaving energy-storage shelf is also introduced. As a limitation, this is a conference presentation; copyright belongs to its owner.

Key points

1. HPR and HPR2 PSUs both accept 180-305 VAC and reach 97.5% peak and 96.5% full-load efficiency including fans.
2. HPR2 doubles output to 49 V/244 A but derates operating ambient to 35 C (HPR: 45 C).
3. Shelf power rises from 33 kW to 72 kW within the same outer dimensions.
4. BBU handover is triggered by AC_LOSS: it starts within 4 ms, runs up to 240 s; PSU hold-up energy is 60 J for loads up to 150%.
5. Pulse-load requirement updated for AI GPUs to 160%/136% of rating.
6. ORv3 1OU shelf: six 5.5 kW rectifiers, 33 kW at N+0 or 27.5 kW at N+1, 50 V, 600 A, 20 ms hold-up.
7. At 277 VAC with 15-160% dynamic load the PSU measured PF 0.998 and iTHD 2.91%.
8. With the input limit at 4.5 kW, a peak to 5.5 kW over 100 ms shut the unit down unless auto-adjust raised the limit.

Using it in design

• Give power shelf catalogue items N+0 and N+1 kW ratings, hold-up time, BBU runtime and allowed peak and pulse-load factors.
• Size shelves for AI racks using the pulse factor (for example 1.6x) rather than average load.
• Warn when shelf ambient exceeds the PSU's rated inlet temperature.

Who should read it

Electrical and rack designers selecting power distribution and power shelves for high-density AI racks.

Related standards

• OCP Open Rack V3 Power Shelf
• OCP ORv3 HPR

Publication details

Authors

Cihan Aydin; Harry Soin

Publisher

Open Compute Project Foundation

Year

2025

Document number

OCP EMEA Summit 2025, DC Physical Infrastructure track

Event

OCP EMEA Summit 2025, Dublin

Document language

English

Source type

Industry body

Access

Free to read

Licence

Copyright retained; citation only — the publisher’s terms apply to the original document

Citation