Data centre design reference

Generic reference designs for power, cooling, controls and operations

Controls and automation

Controls and automation for power and cooling: monitoring, alarms, sequences and safe states.

On this page
  1. The reference control architecture
  2. EPMS, BMS, SCADA and DCIM
  3. Redundancy and safe states
  4. Sequences of operation
  5. Operational security
  6. Alarms people can act on
  7. Sources

The reference control architecture

Power and cooling in a data centre are run by several control systems at once. The reference design keeps them separate where a fault in one must not spread, and joins them where the operator needs one picture.

Reference control architecture: field devices, redundant controllers per block, two independent ring networks, supervisory systems and a guarded enterprise link Field devices report to a redundant controller pair per power block and to the cooling controllers. Protection relays and meters speak IEC 61850 or Modbus TCP to the electrical power monitoring system. Every controller, server and operator station has one connection to each of two independent ring networks, so one cable or switch can fail without losing control. The hot-standby controller pair shares one set of remote I/O. A firewall separates the operational network from the enterprise systems: DCIM, maintenance management and the digital twin. Enterprise network Operational network DCIM capacity, assets Maintenance system work orders Digital twin 3D model, register Firewall and DMZ one-way where possible EPMS server A power monitoring EPMS server B hot standby BMS server cooling, building Operator stations alarms, sequences Historian time-stamped data PLC Block PLC A PLC Block PLC B hot standby PLC Cooling PLC redundant pair Protection relays IEC 61850 M Meters Modbus TCP Ring A Ring A Ring B Ring B Remote I/O shared by the pair Breaker status UPS, generator controllers VFD Pump drives TT TT PT, FT, leak 1. Dotted lines are networks, thin dashed lines hard-wired signals. Ring A and Ring B are independent networks, and every controller and server has one connection to each. 2. Zones and conduits follow IEC 62443: the operational network never depends on the enterprise network to keep power and cooling safe.
Reference control architecture: field devices, redundant controllers per block, two independent ring networks, supervisory systems and a guarded enterprise link
  • Field level. Breakers, protection relays, meters, UPS and generator controllers, pump drives, temperature, pressure, flow and leak sensors.
  • Control level. A redundant controller pair per power block, and redundant controllers for the cooling plant. They run the sequences and hold the safe states.
  • Supervisory level. The electrical power monitoring system (EPMS), the building management system (BMS), operator stations and a historian, on two independent ring networks.
  • Enterprise level. DCIM, the maintenance system and the digital twin, behind a firewall and a demilitarised zone.

EPMS, BMS, SCADA and DCIM

A controls integrator describes BMS, SCADA and EPMS as three layers that have to be coordinated from the start, with most building systems on BACnet and direct digital control, and PLCs on larger plants.1 On the electrical side, IEC 61850 is the international standard for communication with intelligent electronic devices in substations, and its data models map onto several protocols.2 OPC UA provides a platform-independent, service-oriented way to move data between these systems.3

SystemWatches and controlsTypical protocolsReference choice
EPMSBreaker states, protection events, power quality, energyIEC 61850, Modbus TCPDirect from relays and meters, time-stamped at the device
BMSRooms, air handling, fire and leak interfacesBACnetSeparate from the plant controllers that keep cooling running
Plant controllersPumps, CDUs, exchangers, valves, heat sinkPLC networks, OPC UA upwardsRedundant pair, sequences tested at commissioning
DCIMCapacity, assets, rack powerSNMP, Redfish, APIsRead-only from the operational network

Redundancy and safe states

Each block's controllers run as a hot-standby pair, and every controller and server joins both rings, so one cable, switch or controller can fail without losing control. Joining every node to two independent networks is the pattern of the Parallel Redundancy Protocol (PRP); its companion HSR runs one ring of two-port nodes, and PRP and HSR networks can be joined without a single point of failure.4

Design choice. Write down the safe state of every controlled item before writing any logic: what a breaker, a pump drive, a valve and a CDU do when they lose their controller, their network or their power. Power and cooling must keep running in their last safe state with the control system gone. This is engineering practice, not a finding the research run tested.

Sequences of operation

The sequences are where power and cooling meet. The reference set, each tested at commissioning:

  • Loss of one utility supply: the block keeps running on its other power train; generators start; load moves back only after the supply is stable.
  • Loss of both supplies: UPS on battery, generators start and take the load, critical cooling stays on UPS-backed supply throughout.
  • Pump changeover: standby starts on loss of flow or pressure, not only on a drive fault.
  • CDU failure: the remaining CDUs take the load; the operator sees which racks lost redundancy.
  • Loss of the heat sink: an alarm on falling raw-water flow, then a defined load reduction with the IT operator before temperatures move.

Commissioning is usually described in five levels, from factory tests to an integrated systems test; that numbering is an industry convention rather than one published standard, with level 4 as functional performance testing and level 5 as the integrated systems test.5

Operational security

IEC 62443 covers industrial and building automation control systems, so the BMS and plant control networks of a data centre fall within its scope,6 while the organisation's IT infrastructure sits under ISO/IEC 27001.7 In the EU, the NIS2 Directive lists data centre service providers among the entities it covers,8 and where it applies, a significant incident needs an early warning within 24 hours and a notification within 72 hours.8 Check how it applies in Norway before relying on it.

Design position. Zones and conduits from the first drawing: the operational network never depends on the enterprise network to keep power and cooling safe, and data leaves it through one controlled path.

Alarms people can act on

An alarm that does not ask the operator to do something is noise. Every alarm in the reference design names the asset by its register key, the consequence if nothing is done, and the first action. The same key leads to the asset in the 3D model and its history in the maintenance system: see the register-keyed twin.

Sources

  1. BMS Data Center Integration: The Essential Checklist for Construction Success. Proconex, 2026-08-03. Read 2026-10-18.https://www.proconexdirect.com/blog/2026/bms-data-center-integration-the-essential-checklist-for-construction-success/
  2. IEC 61850 (Wikipedia). Wikipedia, 2026-08-23. Read 2026-10-18.https://en.wikipedia.org/wiki/IEC_61850
  3. OPC Unified Architecture (OPC UA). OPC Foundation. Read 2026-10-18.https://opcfoundation.org/about/opc-technologies/opc-ua/
  4. High-availability Seamless Redundancy (Wikipedia). Wikipedia, 2026-09-01. Read 2026-10-18.https://en.wikipedia.org/wiki/High-availability_Seamless_Redundancy
  5. Data center commissioning levels and process field guide. Anvilfield, 2026-06-27. Read 2026-10-18.https://anvilfield.com/field-guides/datacenter/data-center-commissioning-levels-process/
  6. ISA/IEC 62443 Series of Standards. ISA (International Society of Automation). Read 2026-10-18.https://www.isa.org/standards-and-publications/isa-standards/isa-iec-62443-series-of-standards
  7. Applying ISO/IEC 27001, ISO/IEC 27002 and the ISA/IEC 62443 Series for Operational Technology Environments. ISA Global Cybersecurity Alliance, 2025-06. Read 2026-10-18.https://www.isa.org/getmedia/12ce5956-3047-4820-899c-5158722039d9/ISAGCA_Applying-ISO-IEC-27001-2-and-the-62443-Series_White-Paper_2025.pdf
  8. Directive (EU) 2022/2555 (NIS 2) on EUR-Lex. EUR-Lex (Publications Office of the European Union). Read 2026-10-18.https://eur-lex.europa.eu/eli/dir/2022/2555/oj/eng