Power Distribution for Data Centers

What Makes Data Centers Different

Two characteristics define data center electrical design:

• Continuous load. The transformer never gets a break. Linear-load transformer derating curves don't apply — these run at >70% load 24/7/365.
• Non-linear load. Server power supplies and UPS rectifiers create significant harmonic content. The 3rd, 5th, and 7th harmonics dominate, with K-factors typically 13–20.

Combine those two and you have a transformer thermal load profile that punishes anything not designed for it. Standard K-1 transformers fail in 3–5 years on data center duty.

What We Build for Data Centers

• K-13 cast resin transformers for traditional colocation server rooms. Indoor placement, F1 fire class for insurance compliance, low audible noise (5–10 dB below NEMA standard).
• K-20 cast resin or VPI for hyperscale and modern data centers with all-flash compute, where harmonic content runs higher.
• 200% rated neutral on every K-rated unit — triplen harmonics add arithmetically and standard neutrals overheat.
• MV metal-clad switchgear (5–15 kV) in redundant main-tie-main lineups for utility tie. Selectivity coordination is critical: a fault in one server room must not trip an upstream breaker affecting another.
• LV switchboards (UL 891) with high SCCR (100 kAIC+) and arc-resistant construction option for personnel safety during racking operations.

Specification Considerations

Loss Evaluation Drives Spec

At 24/7 operation, every watt of no-load loss is paid for in cooling tonnage too. Lifecycle loss cost over 30 years can exceed initial transformer cost. We provide loss-evaluation calculations on request — a $500 transformer-loss difference, capitalized at typical data center rates, can be worth $20,000.

2N or N+1 Redundancy

Each transformer must carry full load alone in a 2N architecture, or be one of N+1 in a redundant scheme. Sizing has to account for that — a 1000 kW server room on 2N needs two 1500 kVA transformers (with margin), not one.

Sound Levels

Data centers are increasingly office-adjacent (administrative spaces, NOCs). Low-noise transformer design (5–10 dB below NEMA C57.12.91 standard) is often required. Achievable with larger core area, lower flux density.

Equipment Room HVAC

The transformer's losses become heat the HVAC has to remove. Lower-loss design = smaller HVAC. Worth coordinating with mechanical engineering early.

Typical Project Profile

• Service: 13.8 kV utility, dual-feed for redundancy
• Main MV switchgear: 2× 4-section metal-clad lineups with breaker tie, 2000 A bus, 40 kA SC, vacuum breakers, microprocessor relays with selectivity coordination
• Step-down transformers: 4× 2500 kVA cast resin, 80°C rise, K-13, low-noise design, 200% neutral
• Distribution: PDUs and high-density busway downstream
• Lead time: 14–20 weeks (some critical components stocked)
• Witness testing typical for client's electrical engineer