Hyosung Heavy Industries (HICO) EHV/UHV power transformers (69-765 kV, to 2,250 MVA)
Hyosung HICO extra-high-voltage transformers to 765 kV and 2,250 MVA, the only US-built 765 kV line
Hyosung Heavy Industries (HICO) EHV/UHV power transformers (69-765 kV, to 2,250 MVA) is one of 32 data center transformers tracked in the SecondWatt catalogue, each with specifications, lead times and indicative secondary-market pricing.
Hyosung HICO EHV dossier: 69-765 kV to 2,250 MVA from Memphis, 540M USD UHV contract, tariff context, used-market channel, inspection checklist.
Hyosung HICO, the Memphis, Tennessee subsidiary of Korea's Hyosung Heavy Industries, builds extra-high-voltage and ultra-high-voltage power transformers from 69 to 765 kV at up to 2,250 MVA, and claims the position of only US producer of 765 kV transformers. The Memphis plant came from Mitsubishi Electric Power Products in 2019, has absorbed more than 300 million USD since, and a 157 million USD expansion through 2028 will lift capacity roughly 50%, positioning it as the largest transformer production facility in the US with 450+ employees under ISO 9001:2015. Product capability includes DETC and on-load tap changers, integrated real-time diagnostics and online condition monitoring, low-noise designs, and 3D transient, magnetic, thermal, and short-circuit/seismic analysis. Demand evidence is concrete: a 540 million USD contract for 765 kV UHV transformers and reactors with a US transmission operator, deliveries through January 2031, and Hyosung claims roughly half of US 765 kV transformers installed since 2010. Secondary supply is a single data point: a used HICO 500 kV class 134/179/224 MVA shell-type unit at a Michigan dealer, contact for pricing. Korean-origin imports also carry antidumping context (order in force since 2012) and Section 232 tariff exposure, which Memphis production sidesteps.
Why it matters
765 kV is the spine of long-haul US transmission, and exactly one domestic production line exists: this one. With high-capacity lead times at 4 years and GSU demand up 274% since 2019, control of that line is strategic, which the 540 million USD single-customer contract and 157 million USD expansion both confirm. Used EHV supply is effectively brokered one-off inventory.
Who buys it
Transmission operators and utilities building or reinforcing 345-765 kV systems buy this class, alongside hyperscale campuses at transmission-voltage interconnects. The buyer calculus is tariff-shaped: Memphis-built units avoid the 50% Section 232 derivative tariff and the 16.87-22.00% antidumping cash deposits that hit some Korean-built peers.
Role in the data center
Transmission-voltage interconnect transformer for multi-GW campuses taking 345-765 kV service, the single longest-lead asset on such projects.
Key specifications
| Voltage range | 69-765 kV |
|---|---|
| Maximum capacity | 2,250 MVA |
| 765 kV position | only US producer (company claim) |
| Memphis plant origin | acquired from Mitsubishi Electric 2019 |
| Expansion | 157M USD to 2028, ~50% capacity |
| Cumulative investment | >300M USD since 2019 |
| UHV contract | 540M USD, deliveries to 2031-01-31 |
| US 765 kV share since 2010 | ~half (company claim) |
| Observed used unit | HICO 500 kV, 134/179/224 MVA shell type price on request |
Technical summary
Voltage range: 69-765 kV Capacity: up to 2,250 MVA Claim: only US producer of 765 kV transformers Tap control: DETC and OLTC Monitoring: integrated real-time diagnostics, online condition monitoring Engineering: 3D transient, magnetic, thermal, short-circuit/seismic analysis Plant: Memphis TN (ex-Mitsubishi, 2019); ISO 9001:2015; 450+ employees Expansion: 157M USD through 2028, ~50% capacity lift Portfolio also spans ESS, STATCOM/FACTS, HVDC, HV/MV GIS
Pricing and availability
Trend: up Lead time, new: Contract-scheduled; class high-capacity leads to 4 years. Lead time, used or refurbished: 2-12 weeks. Warranty, used: 3-year typical from major US rebuilders.
Lifecycle and maintenance
Liquid-filled transformers routinely serve 30-40 years with annual oil screening, DGA on a 1-2 year cadence (or continuous online monitoring on critical units), and gasket or bushing service as tests dictate. Major US rebuilders remanufacture units to like-new condition with warranties up to 3 years (T&R Electric, Sunbelt Solomon), and reconditioned stock ships in days against 65-210 week new-build queues. Remaining paper life, estimated by furan testing, governs end-of-life valuation.
Common failure points
- Windings — Dielectric failure; windings dominate major-failure statistics in CIGRE TB 642
- Bushings — Failure share rises with voltage class; OIP bushing faults can rupture tanks
- OLTC — Contact and mechanism wear; prominent failure source on substation units
- Winding deformation — Through-fault or transport damage shifting SFRA signature
- Cooling system — Pump, fan, and radiator degradation derating the unit
- Moisture and paper aging — Furans in oil and reduced degree of polymerization
Inspection checklist
DGA — dissolved gas analysis per IEEE C57.104; combustible-gas trend rise between 2 samples triggers investigation Oil quality — dielectric breakdown, moisture, acidity, and furan tests; degree of polymerization below 200 marks end of paper life Insulation resistance — megger HV/LV/ground; polarization index of 2.0 or higher passes Power factor — insulation power factor testing; values above 1.0% on oil-filled windings warrant investigation Turns ratio — TTR on all taps; deviation beyond 0.5% from nameplate fails Winding resistance — three-phase balance within 2% between phases Bushings — capacitance and power factor test; bushing failure share rises with voltage class per CIGRE TB 642 OLTC — inspect on-load tap changer diverter and selector; OLTCs are a leading failure component in CIGRE TB 642 fleet surveys SFRA — sweep frequency response analysis per IEEE C57.149 against baseline to detect winding deformation after transport Transport records — review impact-recorder data per IEEE C57.150 for any relocated unit of 10 MVA and above Core ground — verify a single intentional core ground; inadvertent grounds show as gassing in DGA Cooling — inspect radiators, pumps, and fans; verify stage ratings (ONAN/ONAF) against nameplate Tank and conservator — corrosion survey, gasket inspection, and pressure relief device function Nameplate verification — confirm MVA stages, impedance, BIL, and 55/65 C rise data against the factory test report Records — complete factory test report, DGA history, through-fault history, and loading records from service
Procurement channels
Direct contract with Hyosung HICO for new; used EHV supply is brokered dealer inventory (Transformer Exchange's HICO 500 kV unit the only observed example), universally price-on-request.
Regional notes
Korean LPT antidumping order in force since 2012-08-31: 2022-23 final results set Hyundai at 0.00% and others at 16.87-22.00% cash deposit (Hyosung's rate not in that review). Section 232 50% tariffs cover transformer derivative content from 2025-08-18; Memphis production avoids both.