Medium voltage on the rise: How MV systems can cut costs and boost efficiency in data centers

Overview

The article defines medium voltage as 1,000-38,000 V and ties its main argument to current: the same power at higher voltage means lower current, which cuts voltage drop and conductor count. It states that low-voltage systems may need 8-10 times as many cables and conduits as an equivalent MV system. Moving the transformer closer to the load frees white space.

Protection differs too. MV breakers house only the vacuum interrupter while the protection function sits in separate microprocessor relays, which allows faster and more flexible protection settings. Working clearances also change: about 3 ft (0.9 m) in front of LV gear is enough, while MV needs at least 4 ft (1.2 m) and sometimes rear access.

The costs are spelled out: individual equipment items occupy more space, working clearances widen and maintenance needs specially qualified staff. MV therefore trades cable and loss savings for site area and operating skill, and the balance tips toward MV only in halls of MW scale. This 2015 article is short and qualitative: apart from the cable ratio it gives no cost or efficiency figures, and it is written from a manufacturer's advocacy viewpoint. For today's AI campuses of hundreds of MW, newer documents that develop the same argument at larger scale are the better reference.

Key points

1. MV range defined as 1,000-38,000 V
2. LV systems may need 8-10x as many cables and conduits as an equivalent MV system
3. Working clearance: ~3 ft (0.9 m) in front of LV gear vs >=4 ft (1.2 m) for MV, sometimes rear access
4. MV breakers house only the vacuum interrupter; protection is in separate microprocessor relays
5. Costs: larger equipment footprint, wider clearances, specially qualified maintenance staff

Using it in design

• In the layout engine default front working clearance to 1.2 m for MV switchgear and 0.9-1.0 m for LV, with a jurisdiction override (e.g. NEC 110.26/110.34).
• In the electrical module offer MV ring/radial to unit substations near the load for halls above a few MW.
• In cable-count comparisons show the 8-10x LV multiplier as a first estimate.
• When MV is chosen, add the need for qualified maintenance staff to project assumptions.

Who should read it

Electrical designers deciding between LV and MV distribution in data centers whose halls exceed a few MW.

Related standards

• NEC 110.26 / 110.34
• IEC 62271-200
• IEC 61439

Publication details

Authors

ABB

Publisher

ABB

Year

2015

Document number

9AAK10103A1445

Document language

English

Source type

Manufacturer

Access

Free to read

Licence

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

Citation