From Grid to Rack

Glossary

Firm capacity

The amount of power the grid guarantees to deliver at all times, including during contingencies when a line or transformer is out of service. It contrasts with non-firm capacity, which can be curtailed when the grid is stressed.

Interconnection queue

The ordered, studied pipeline through which a grid operator evaluates and approves new large connections. Projects are now commonly studied in clusters, and a site's real timeline depends on its position and on the readiness of projects ahead of it.

Medium-voltage distribution

The campus-scale network that carries power from the substation to each building at an intermediate voltage, keeping current and losses low over distance. Its layout — radial, ring, or dual-feed — sets campus resilience before power enters any hall.

Point of interconnection

The physical and contractual place where a site's electrical equipment meets the grid, defined by firm megawatts, voltage class, fault duty, and an energization date. It sets the hard ceiling on how much power the site can ever draw and when.

Power usage effectiveness (PUE)

The ratio of total facility power to the power delivered to IT equipment. It captures the overhead of power conversion and cooling; conversion losses count twice, as wasted input and as heat the cooling system must then remove.

Step-down transformer

A device that converts a higher voltage to a lower one using magnetically coupled coils with no moving parts, at better than 99 percent efficiency. Large power transformers are custom-built with multi-year lead times and often govern a project's energization date.

Topology tier

A description of how many independent power paths run from the building transformer to the rack and how many simultaneous failures or maintenance actions the site can absorb. It is a countable physical property of the wiring, not a marketing label.

Uninterruptible power supply (UPS)

Equipment that inserts stored energy into the power path so the load rides through grid disturbances without interruption. In a double-conversion design a battery on the DC link feeds the inverter, bridging the seconds until standby generators start.