# HV switchgear, GIS, breakers, protection relays

Part ID: 7.02 · Layer 7 (Electrical: power distribution (grid to rack))

The high-voltage switching, protection, and fault-isolation gear between the substation transformers and the campus's medium-voltage distribution, including gas-insulated (GIS) designs for compact sites.

HV switchgear does the actual switching and fault protection at transmission-adjacent voltages, working alongside the transformers in 7.01 to get power safely onto the campus's medium-voltage backbone (7.03, 7.04). Breakers interrupt fault current, protection relays detect faults and command the breakers, and gas-insulated switchgear (GIS) packages the same function into a sealed, compact footprint useful where land or setback rules constrain a substation; air-insulated switchgear remains the default where space is not the binding constraint. Like the transformers next to it, HV switchgear is a custom-engineered, utility-qualified product line, so it shares the same order-book dynamics: a campus that orders several transformers at once is also ordering matching breaker bays and relay panels, and the industry that has long supplied utilities is now also supplying data centers competing for the same slots. A shift toward SF6-free breaker designs, driven by regulatory pressure on the potent greenhouse gas SF6, adds a qualification cycle on top of ordinary lead time as buyers weigh proven SF6 designs against newer alternatives. For investors, the relevant signals are the same backlog and capacity-expansion metrics as transformers, plus how fast SF6-free designs get qualified by utilities and hyperscalers, since that transition could reshuffle who wins new orders.

**AI delta:** AI campuses ordering multiple large transformers at once are also multiplying HV switchgear and breaker orders, pulling on the same protection-relay and GIS supply chains already stretched by grid buildout.

## Companies

| Company | Role | Confidence | Ownership | Ticker | Note |
|---|---|---|---|---|---|
| ABB | manufacturer | inferred | public | ABBN.SW |  |
| Eaton | manufacturer | inferred | public | ETN |  |
| GE Vernova | manufacturer | inferred | public | GEV |  |
| Hitachi Energy | manufacturer | inferred | subsidiary |  |  |
| Hyosung Heavy | manufacturer | inferred | public | 298040.KS |  |
| Hyundai Electric | manufacturer | inferred | public | 267260.KS |  |
| Mitsubishi Electric | manufacturer | inferred | public | 6503.T |  |
| Nari | manufacturer | inferred | public | 600406.SS |  |
| Pinggao | manufacturer | inferred | public | 600312.SS |  |
| Schneider Electric | manufacturer | inferred | public | SU.PA |  |
| Siemens Energy | manufacturer | inferred | public | ENR.DE |  |
| Sieyuan | manufacturer | inferred | public | 002028.SZ |  |

Confidence tags: disclosed = company/filing statement; reported = trade press or partner list; inferred = taxonomy lead.