Data Centre Campus Design:
Multi-Building Power Sharing
and Utility Coordination

The hyperscale data centre campus has become one of the most demanding electrical infrastructure projects an engineer can encounter. A 200 MW campus draws more power than many Indian district substations. Its grid connection process involves the same regulatory approvals, transmission studies, and protection coordination exercises as a small power plant. Its internal HV ring network must deliver absolute reliability to dozens of independent buildings, each of which is itself designed for Tier III or Tier IV uptime. And it must do all of this while being designed in phases — because no developer commits to 200 MW on day one.

This article addresses the engineering of the campus power and utility infrastructure — from the grid connection point to the individual building substation — with particular attention to the decisions that cannot easily be undone once construction begins.

Understanding Campus Scale in India

India’s data centre sector is undergoing a structural shift. The era of 5–20 MW standalone colocation facilities in Mumbai and Chennai is giving way to hyperscale campus developments of 100 MW and above at purpose-built locations in Navi Mumbai, Pune, Hyderabad, Chennai, and the National Capital Region. Several announced campuses exceed 500 MW of ultimate IT load capacity.

Grid Connection Strategy

The grid connection is the longest-lead-time element of any data centre campus — typically 18–36 months from application to energisation in India, depending on the voltage level, DISCOM/TRANSCO workload, and whether new transmission infrastructure is required. The grid connection strategy must be resolved at the earliest stage of project development — it cannot be deferred to detailed design.

Voltage Level Selection

Dual Feed Requirement

Any data centre campus of meaningful scale must have two independent grid connections from geographically separated grid substations. A single feed — even from the most reliable TRANSCO substation in the state — exposes the entire campus to a single point of failure: transformer failure, feeder fault, or substation outage. The two feeds must originate from different busbars at different grid substations with separate transmission line routes. Independence on paper but shared overhead line poles for the final kilometre is not genuine independence.

// Dual feed power balance — 200 MW campus, 132 kV, two independent feeders

// Normal operation: both feeds active, load shared
Feed A  = 100 MW  (50% of campus load)
Feed B  = 100 MW  (50% of campus load)

// N-1 contingency: one feed lost — surviving feed must carry full campus load
Feed A (sole supply) = 200 MW
// Each feeder cable and transformer must be rated for 200 MW continuous
// NOT 100 MW — N-1 capacity must be sized for full campus load

// 132 kV feeder current at 200 MW, 0.95 PF, 3-phase
I_feeder = P / ( √3 × V × PF )
          = 200×10⁶ / ( 1.732 × 132×10³ × 0.95 )
          = 922 A  →  specify 1,200 A cable (XLPE 3×400 mm² Al, 132 kV)

On-Site Grid Receiving Substation

For campuses above 50 MW, a dedicated on-site or adjacent receiving substation — owned by the campus developer and maintained by the developer’s O&M team — is strongly preferred over metering at a DISCOM substation and distributing at HV. The receiving substation contains the primary metering point, protection relays, surge arresters, and the campus HV busbar from which all buildings are fed. Key decisions at this stage:

• GIS versus AIS: Gas-Insulated Switchgear is the default for campuses where land is at a premium or the substation must be indoor. AIS is cost-effective where open land is available and environmental conditions permit. See KVRM’s GIS-specific guidance at Power Transformer Selection for GIS Substations →
• Transformer number and sizing: Two primary transformers (132/33 kV or 132/11 kV) in N+1 configuration. Each rated for 100% of campus design load for N-1 compliance. Transformer capacity must include the ultimate campus build-out load, not just Phase 1.
• Spare transformer strategy: At campus scale, transformer replacement lead times of 12–18 months are unacceptable. Either a spare transformer is held on site in a storage bay, or a contract with the OEM guarantees a defined delivery time for a replacement unit. Specify this requirement in the procurement documents.

Campus HV Ring Network

The campus HV ring is the arterial power distribution network connecting the receiving substation to each building’s dedicated substation. Its design determines the fault isolation capability, maintenance flexibility, and expansion capacity of the entire campus for its lifetime.

Ring Topology Options

HV Ring Cable Specification

Campus HV ring cables — typically 33 kV or 66 kV XLPE insulated, armoured, direct-buried — must be specified for the ultimate campus load, not the Phase 1 load. Undersized cables buried under roads and hardstanding cannot be upsized without disruptive civil works. Calculate cable rating for the N-1 condition (one ring section faulted; surviving section carries full campus load) with the appropriate derating factors for ground temperature, depth of burial, and thermal resistivity of the backfill material.

// 33 kV campus ring cable sizing — 100 MW campus, N-1 condition

// N-1 load on surviving ring section: 100 MW, PF = 0.95
I_ring = P / ( √3 × V × PF )
        = 100×10⁶ / ( 1.732 × 33×10³ × 0.95 )
        = 1,843 A

// Standard 33 kV XLPE cable ratings (IEC 60502-2, buried 1.0 m, 25°C soil):
// 3×500 mm² Al XLPE: ~680 A per cable  →  3 cables per section required
// 3×630 mm² Al XLPE: ~755 A per cable  →  3 cables per section (preferred)

// Derating for Indian conditions (soil temp 35°C, depth 1.2 m):
Derating factor ≈ 0.88  →  effective rating: 755 × 0.88 = 664 A per cable
3 cables in parallel = 1,992 A  >  1,843 A  ✓  (8% margin)

// Each cable in a separate duct or trench — no bunching derating
// Specify minimum 1.0 m spacing between cable trefoil groups

Per-Building Substation Design

Each building on the campus has its own dedicated substation — receiving HV from the campus ring and stepping down to LV for UPS, switchgear, and mechanical services. The per-building substation design must balance independence (each building completely self-contained) with campus-level coordination (shared HV protection philosophy, compatible metering, common SCADA).

Substation Capacity and Transformer Configuration

Each building substation is sized for its specific building load — typically 2 × 100% rated transformers in N+1 configuration. Transformer capacity is specified at the building’s ultimate IT load plus all mechanical and ancillary loads, with a 15% growth margin. The two transformers feed independent A-bus and B-bus LV distribution boards, maintaining the 2N power path from HV ring to rack PDU.

Protection Coordination Across the Campus

With multiple buildings connected to a common HV ring, protection coordination is a campus-level engineering exercise — not something each building substation designer can resolve independently. The protection philosophy must ensure that a fault within any building substation is isolated by that building’s HV incomer protection without tripping the campus ring. Simultaneously, a fault on the ring cable must be isolated by the ring protection without affecting healthy buildings. This requires a graded time-overcurrent protection scheme with:

• 01

  Directional Overcurrent Relays at Each Building Incomer

  Directional protection at each building HV incomer trips only for faults within the building — not for through-fault currents from ring faults elsewhere. This is the essential element that prevents a building transformer fault from propagating an outage to adjacent buildings. Specify numeric protection relays (IEC 61850 compatible) from the outset — electromechanical relays cannot provide the selectivity required in a multi-source ring.

• 02

  Distance Protection on Campus Ring Feeders

  For campus rings above 33 kV, distance protection (impedance-based) provides faster and more selective fault isolation than overcurrent relays. Distance protection can isolate a ring cable fault within 80–100 ms without needing to grade time settings against all other relays in the ring. Pilot wire or optical fibre communication between ring section relays enables current differential protection — the fastest and most selective option for high-reliability campus rings.

• 03

  Automatic Bus Transfer (ABT) at Building Level

  Each building’s LV main switchboard includes an automatic bus-transfer scheme that detects loss of supply on either the A-bus or B-bus transformer and automatically closes the bus coupler within 100 ms — restoring supply to the affected bus from the healthy transformer. The ABT scheme must be tested under load as part of building commissioning, not just on no-load signal injection.

• 04

  Arc Flash Protection (Bus Bar Differential)

  At 33 kV, an arc flash within a building substation generates enormous fault energy that can cause catastrophic structural damage and personnel injury before an overcurrent relay operates. Arc flash detection relays — using light sensors to detect the arc flash luminosity — operate within 10 ms, far faster than any overcurrent relay. Mandatory for indoor 33 kV switchgear rooms where personnel may be present during live operations.

Phased Power Delivery Strategy

No campus developer funds 200 MW of infrastructure before a single tenant has been signed. Campus development is inherently phased — and the power infrastructure must be designed to accommodate phased delivery without stranding capital, creating bottlenecks, or requiring disruptive modifications to energised infrastructure as phases are added.

The Stranded Capital Problem

Oversizing early-phase infrastructure to accommodate ultimate campus build-out is expensive. Building infrastructure that must later be modified or supplemented as load grows is also expensive. The engineering solution is phased stub design — infrastructure that is physically installed to ultimate capacity in the civil and HV elements (buried cables, cable ducts, substation civil works) where modification is expensive, but where equipment is populated incrementally to match actual load (transformers, switchgear, UPS modules) where modification is cost-effective.

Shared Campus Utilities: Water, Cooling, and Fuel

Beyond power, a large campus shares significant non-electrical utility infrastructure. The decision of what to share versus what to make building-independent is one of the most consequential campus planning decisions — affecting both capital cost and operational resilience.

Cooling Water — Shared vs. Independent

Diesel Fuel — Storage and Distribution

A 200 MW campus with N+1 generator sets requires large-scale diesel fuel infrastructure — storage, distribution, and automated fuel management that is often underspecified at concept stage. Key considerations:

• Bulk storage: Minimum 48-hour runtime at full campus load. For a 200 MW campus at 40% load diversity, this equates to approximately 1,800 kL of diesel storage — requiring multiple large above-ground tanks or underground storage compliant with PESO regulations.
• Day tanks per building: Each building generator has a local day tank (8–12 hours runtime) fed from the bulk storage by an automated fuel management system. Day tank overflow and leak detection must integrate with the BMS.
• Fuel polishing: Bulk diesel stored for extended periods degrades — microbial growth, water contamination, and sedimentation. Fuel polishing systems (continuous filtration and microbial treatment) are mandatory for bulk storage serving critical generators.
• Fuel delivery access: Campus road design must provide unimpeded tanker access to bulk storage filling points at any time, including during high-occupancy periods. This is a site planning requirement, not just a logistics one.

Water Supply — Process, Cooling, and Fire

Campus-Level Power Management and SCADA

A multi-building campus requires a campus-level Energy Management System (EMS) that sits above the individual building BMS systems and provides integrated visibility, load balancing, and automated response across the entire campus power infrastructure.

• 01

  Integrated Campus SCADA

  All HV switchgear, campus ring protection relays, receiving substation, building substations, and generators communicating via IEC 61850 GOOSE and IEC 61968 CIM to a single campus SCADA platform. Real-time visibility of all campus power flows, loading levels, and fault conditions. Alarm management with intelligent grouping — a campus of 20 buildings can generate thousands of alarms per day; unmanaged alarm floods are a known cause of operator error during critical events.

• 02

  Campus Load Shedding and Demand Response

  When campus total load approaches a contracted grid capacity limit — common during summer peak periods — the campus EMS must be capable of automated load shedding to avoid demand charges or supply interruption. Load shedding priority lists (non-critical loads first: EV chargers, office HVAC, lighting) must be pre-programmed and tested before the grid imposes constraints. Demand response participation in grid ancillary service markets is an emerging revenue stream for large campuses.

• 03

  Renewable Integration and Dispatch

  Campus EMS manages the dispatch of on-site solar PV, wind, or BESS against real-time grid draw to minimise energy cost and carbon intensity. The EMS must handle anti-islanding detection and grid code compliance for all on-site generation assets, ensuring no export to the grid without proper metering and approval from the relevant DISCOM.

• 04

  Power Metering and Commercial Allocation

  In multi-tenant campuses, energy metering must apportion campus-level utility costs to individual buildings and tenants. Separate metering points at each building HV incomer (for DISCOM billing purposes) and at each tenant’s distribution board (for colocation billing) are both required. The metering architecture and data integration with billing systems must be agreed with tenants before building commissioning.

India Regulatory and Statutory Framework

Campus-scale power infrastructure in India involves a web of statutory approvals, technical standards, and regulatory obligations that differ from those applicable to a single building data centre. Engineers and developers who underestimate this complexity consistently face approval delays that are far more damaging than any technical challenge.

Campus Power Infrastructure Checklist

Conclusion: Campus Infrastructure as a 30-Year Decision

Every decision made in the design of a data centre campus power infrastructure will be lived with for thirty years. The grid connection agreement, the HV ring topology, the cable duct routes under the campus roads, the substation civil structure with its spare bays — these are not items that can be revised at the next project phase. They are commitments.

The developers and engineers who get this right are those who force the long-horizon questions to the front of the programme: What is the ultimate campus load and how many phases will it take to reach it? Can the grid actually supply that load from this location and what are the realistic timelines? What does the phased power delivery look like and what civil infrastructure needs to be in the ground from day one to enable it? How will the campus infrastructure remain maintainable at full operation without outages?

India’s data centre sector is building the infrastructure that will define the country’s digital economy for a generation. The campuses being designed today are not just construction projects — they are the foundation of a national capability. Engineering them correctly is not optional.