Open Rack V3 HPR V2 72kW Power Shelf, Rev 1.0.0 (June 12, 2026)

Overview

The document defines the high-power version of the Open Rack power architecture, in which centralised, scalable power shelves feed rack payloads over a common busbar and house several PSUs with at least N+1 redundancy. The first OCP release is 1.0.0 of 12 June 2026. Two options exist: option 1, six 12 kW PSUs with dual cords (2x 60 A NEC breakers upstream) and option 2, dual cords with 2x 63 A IEC breakers. Both give 60 kW with N+1 and connect directly to tap-boxes without an intermediate PDU. This is a component-level document; the 12 kW PSU, PMM, BBU and AC whip have separate documents.

AC input is 230-277 V nominal phase-to-return and PSUs must withstand continuous 305 Vac RMS; input is through a configurable 5-pin connector and AC earth is bonded to the chassis. Facility protection is 2x 60 A NEC (or 60/63 A IEC) breakers for the 2-feed 1U shelf, with 40 kA available short-circuit current. DC output follows the narrow-range 48 V architecture: PSU output is nominally 50 V (adjustable). The stated reasons, compared with ORv2's 40-60 V range, are to avoid oversized voltage and current design, to enable 4:1 fixed-ratio converters and conventional 12 V PoL converters, and to let power flow naturally without software dependency. Ripple and noise stay below 500 mV peak-to-peak at 20 MHz.

The pulse-load clause requires each PSU to support repetitive peak loads while holding regulation and the input power limit, without triggering BBU backup: up to 140% on a 50 ms moving average, up to 160% on a 400 us moving average and 100% on a 1 s or longer moving average. AC_Loss signals were added to PSU and BBU shelves so the BBU starts discharging immediately on AC loss. When a PSU has depleted its bulk capacitor energy under a pulse load, it asserts Pulse_Mgmt_L to request load sharing, and each BBU checks its charge to decide whether to share. The design must support at least ten power shelves in parallel.

For monitoring, each shelf carries a monitoring module (PMM) reached through I2C to the shelf EEPROM (M24128-BR or equivalent, 100 kHz target) and through Modbus registers. Two thermistors on the DC output connector (positive and negative contacts) must support at least 150 C; the PSU sets an alarm bit at a warning threshold and shuts down at the safety threshold. Three rear USB-C connectors read NTC thermistors in the horizontal busbars, and the PMM issues a shutdown command to PSU and BBU modules on over-temperature. The envelope is 537 mm W x 46.2 mm H x 867.5 mm D; airflow is front to back, upstream exhaust should not exceed 75 C and a rear back-pressure of 1.5 in of water or less above 250 CFM is targeted.

Environmental conditions are -5 to +45 C operating, 10-90% RH non-condensing, -40 to +70 C storage, no derating to 3050 m, G1 gaseous contamination and an 85 dBA target. The document also covers vibration and shock and package tests, worst-case component stress analysis (WCSA), reliability prediction, DFMEA, zinc-whisker controls, manufacturing tests, product change notification and compliance requirements. The materials chapter sets post-consumer recycled (PCR) plastic targets and supplier qualification, and the OCP tenets chapter stresses that the mechanical envelope, electrical interfaces, connectors and monitoring architecture are all openly specified.

Key points

1. The shelf has six 12 kW PSU slots and dual AC cords, delivers 60 kW with N+1 redundancy and connects directly to tap-boxes with no intermediate PDU.
2. AC input is 230-277 V nominal phase-to-return at 50/60 Hz; PSUs must withstand continuous 305 Vac RMS.
3. Facility protection is 2x 60 A NEC (or 60/63 A IEC) breakers per 2-feed shelf with 40 kA available short-circuit current.
4. Narrow-range 48 V architecture: PSU output nominally 50 V (adjustable), ripple and noise under 500 mV peak-to-peak at 20 MHz, 48 V return not grounded to the frame.
5. Repetitive peak load capability: up to 140% for 50 ms, 160% for 400 us and 100% for 1 s or longer moving averages, without triggering BBU backup.
6. AC_Loss and Pulse_Mgmt_L signals between PSU and BBU shelves coordinate load sharing during AC loss and pulse loads.
7. Thermistors on the DC output connector must support at least 150 C, with an alarm at the warning threshold and shutdown at the safety threshold.
8. Shelf envelope is 537 mm W x 46.2 mm H x 867.5 mm D (1 OU).
9. The design must support parallel operation of at least ten power shelves.
10. Environment: -5 to +45 C operating, 10-90% RH non-condensing, no derating to 3050 m, G1 contamination, 85 dBA target.

Using it in design

• Size rack feeds by option: two independent 60 A NEC or 63 A IEC circuits, protection suited to 40 kA available short-circuit current at the tap-box, and no PDU in between.
• Compare the 230-277 V phase-to-return window and the 305 Vac continuous withstand with the facility voltage design, and verify the AC whip cable rating in its separate OCP document.
• When converting rack power budget to a number of 60 kW N+1 shelves, account for load pulses of 140% for 50 ms and 160% for 400 us and for the BBU and Pulse_Mgmt coordination.
• Plan to connect the busbar temperature points (output connector and three horizontal busbars) to the BMS or rack management controller via Modbus, and fix alarm and shutdown thresholds at commissioning.
• Check rear airflow exit and pressure drop against the 1.5 in water target above 250 CFM, the hall environment against -5 to +45 C, 3050 m and G1, and add the 48 V busbar ripple limit to acceptance testing.

Who should read it

Power electronics engineers designing high-power ORv3 shelves and PSUs, and designers planning in-rack and branch-level power for high-density racks.

Document contents

1. Revision History
2. Scope and Overview
3. Power Shelf Options (NEC and IEC breakers)
4. AC Electrical requirements
5. DC Electrical requirements
6. PSU physical addressing
7. Monitoring & Control Interface (shelf EEPROM with I2C)
8. AC_Loss and Pulse_Mgmt Signal Connector
9. Peak Load requirements
10. Parallel Operation Mode with Multiple Shelves
11. Grounding
12. Shelf Output Busbar Temperature Sensing and Monitoring
13. Mechanical Requirements
14. Rack Mounting Features
15. Connectors (AC input, DC output, power supply, PMM, ISHARE, busbar temperature)
16. Materials and Fasteners (PCR targets)
17. Thermal Requirements
18. Environment/test requirements
19. Reliability and Quality
20. Manufacturing Quality Control and Testing
21. Compliance requirements
22. Compliance with OCP Tenets

Read the document

Publication details

Authors

Jingjing Sun; Mohammed Alisa; David Sun; Wenying Zhang; Dmitriy Shapiro; John Fernandes; Ben Kim; Baby Neil Escuadro; Siu Lam

Publisher

Open Compute Project Foundation

Year

2026

Document language

English

Source type

Industry body

Access

Open licence — downloadable

Licence

OWFa 0.9 — Open Compute open specification licence; redistribution permitted

Licence evidence

www.opencompute.org

Citation