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Glossary — Energy & Industrial Equipment Terms

Plain-language definitions for the standards, acronyms, and terms that show up across data center, renewable, storage, oilfield, and industrial MRO procurement.

These are quick, accurate reference definitions — for the full context behind FEOC compliance or transformer lead times specifically, see the dedicated guides linked at the bottom of this page.

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ANSI C57API 5CTAPI 6AAPI 7KAPI 16A BOPBOSChristmas treeDC block Domestic content bonusFEOC Grid-forming vs. grid-followingGSU transformerITC kVA vs. kWMCCBNFPA 855OCTG PCSSafe harborUL 9540A

ANSI C57

The IEEE/ANSI C57 standard series governs power transformer design, testing, and performance requirements in North America. It's the reference behind most of the specs on the Data Centers desk's transformer listings.

API 5CT

An American Petroleum Institute specification covering casing and tubing — collectively OCTG — used in oil and gas wells.

API 6A

API specification covering wellhead and christmas tree equipment.

API 7K

API specification covering drilling and well-servicing structural equipment, including derricks and masts.

API 16A

API specification covering drill-through equipment, including blowout preventers (BOPs).

BOP (Blowout Preventer)

A large valve/stack assembly used to seal, control, and monitor an oil or gas well, preventing an uncontrolled release of fluids. Covered under API 16A on the Oil & Gas desk.

BOS (Balance of System)

Every component of a solar or storage installation other than the modules themselves — racking, wiring, trackers, and inverters. See Renewables for BOS families in the catalog.

Christmas tree (wellhead)

The assembly of valves, spools, and fittings mounted on top of a wellhead used to control production flow, typically covered under API 6A.

DC block (BESS)

A modular, pre-integrated battery rack/module unit that serves as a building block of a larger battery energy storage system — see the Battery Storage desk's Storage Blocks category.

Domestic content bonus

An additional US tax credit percentage available to projects meeting domestic-manufacturing thresholds for steel, iron, and manufactured components — evaluated separately from FEOC status. See the FEOC compliance guide for how the two interact.

FEOC (Foreign Entity of Concern)

Restrictions on component sourcing that determine whether a solar or storage project's components disqualify it from ITC eligibility and the domestic-content bonus. Full detail in the FEOC compliance guide.

Grid-forming vs. grid-following

Grid-forming inverters/PCS can establish their own voltage and frequency reference and operate independent of the grid. Grid-following equipment instead synchronizes to an existing grid signal. Both appear on the Battery Storage desk's Power Conversion category.

GSU transformer (Generator Step-Up)

Steps up voltage from a generator to transmission-line levels — used at power plants, substations, and utility-scale renewable sites.

ITC (Investment Tax Credit)

The federal tax credit for renewable energy and storage projects under IRC Section 48/48E, subject to FEOC and content-sourcing rules.

kVA vs. kW

kVA (kilovolt-amperes) measures apparent power; kW (kilowatts) measures real, usable power. The ratio between the two is the power factor — relevant when sizing transformers and generators.

MCCB (Molded-Case Circuit Breaker)

An overcurrent protection device typically rated up to about 2,500 A, sitting between miniature breakers and large power breakers.

NFPA 855

The National Fire Protection Association standard for the installation of stationary energy storage systems — a core compliance reference for the Battery Storage desk. See the BESS fire safety basics guide for what it actually requires.

OCTG (Oil Country Tubular Goods)

The collective term for tubulars used in oil and gas wells: casing, tubing, and drill pipe, typically specified under API 5CT.

PCS (Power Conversion System)

Equipment that converts DC battery power to AC (and back) for grid interconnection in a BESS — see grid-forming vs. grid-following for the two operating modes.

Safe harbor (construction)

IRS provisions that let a project lock in tax-credit eligibility by beginning construction or incurring qualifying costs before a deadline — referenced directly in the FEOC compliance guide.

UL 9540A

A UL test method evaluating thermal runaway fire propagation in battery energy storage systems, alongside NFPA 855 installation requirements. See the BESS fire safety basics guide for how the two standards fit together.

Want the full story behind a term?

The transformer lead-time and FEOC compliance guides go deep on the two topics referenced most above.

SEE ALL GUIDES →