Hyosung 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, built in Memphis, Tennessee since 2019
This model is part of SecondWatt’s transformer research catalogue. Specifications and price observations are included where supported by sources. Equipment availability and commercial terms require confirmation.
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-gigawatt campuses taking 345-765 kV service. This is utility-yard equipment rather than data-hall gear, and on projects at that scale it is the single longest-lead asset, with high-capacity power transformers quoting up to four years in 2026.
Key specifications
| Voltage range | 69-765 kV |
|---|---|
| Maximum capacity | 2,250 MVA |
| 765 kV position, company statement | Hyosung HICO describes itself as the only US producer of 765 kV transformers |
| 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, company statement | about half of US 765 kV transformers installed since 2010 |
| Observed used unit | HICO 500 kV, 134/179/224 MVA shell type price on request |
| Tap control | DETC and on-load tap changers |
| Monitoring | integrated real-time diagnostics and online condition monitoring |
| Memphis workforce | 450+ employees |
| Quality certification | ISO 9001:2015 |
| Korean LPT antidumping order | in force since 2012-08-31 on units of 60 MVA and above |
| Section 232 derivative tariff | 50% on non-US steel and aluminum content, effective 2025-08-18 |
Technical summary
Voltage range: 69-765 kV. Capacity: up to 2,250 MVA. Company statement: Hyosung HICO describes itself as the 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.
Major variations
Core-type and shell-type EHV designs cover generator step-up and autotransformer duties, with de-energized or on-load tap changers specified per project. The split that matters commercially is manufacturing origin: the Memphis line builds US-standard units, while Korean plants serve global orders and are exposed on import to the Korean large power transformer antidumping order and to Section 232 derivative tariffs. Hyosung HICO's wider portfolio spans energy storage, STATCOM and FACTS, HVDC and high- and medium-voltage gas-insulated switchgear, so transformers are often quoted inside a larger substation package.
Configurations and options
The line spans 69-765 kV to 2,250 MVA in core-type and shell-type designs covering generator step-up and autotransformer duties. Tap control is a de-energized tap changer or an on-load tap changer specified per project, and the on-load option is the largest single cost and maintenance adder. Integrated real-time diagnostics and online condition monitoring are offered as part of the build rather than as a retrofit. Low-noise designs are available. The engineering package behind the order includes 3D transient, magnetic field, thermal and structural short-circuit and seismic analysis. Commercially the largest option is not on the transformer at all but on the order: manufacturing origin, Memphis against Korea, decides antidumping and tariff exposure. BIL, cooling classes and IEEE detail sit in the Hyosung HICO transformer catalog rather than on the product page as of August 2026.
Compatibility and dependencies
This is transmission-yard equipment and its interfaces are switchyard interfaces. High-voltage bushings at up to 765 kV land on the yard bus or a gas-insulated connection; the low-voltage side follows the duty, with a generator step-up delta winding going to isolated-phase bus. Impedance sets the duty on the switchyard breakers, BIL has to coordinate with the arrester scheme at the installed class, and a wye winding's neutral needs a defined grounding path. An on-load tap changer needs control power, a motor drive and a cabinet. The integrated condition monitoring needs a comms path and a SCADA point list. Transport dominates the schedule at this size: IEEE C57.150-2023 applies at 10 MVA and above, and route survey, heavy-haul arrangements and impact recording have to be settled before the unit ships. The site needs containment and fire separation per FM Global Data Sheet 5-4.
Pricing and availability
Trend: rising Electrical Trader's price history, published 2026-04-01, puts power transformer prices up 77% between 2019 and 2026 and generator step-up transformers up 45% since 2019, on copper up roughly 70% and grain-oriented electrical steel up 80-100% from 2020 to 2025. It records Q2 2025 lead times of 128 weeks for power transformers and 144 weeks for GSUs. PwC figures reported by pv magazine USA on 2026-05-11 put high-capacity units at up to four years, with GSU demand up 274% between 2019 and 2025. 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.
Thermal and emissions profile
Transformers produce no combustion emissions; the regulatory profile is efficiency and fluid. US distribution-class units fall under DOE 10 CFR 431 Subpart K efficiency standards, amended in 2024 with compliance from 2029 requiring 10-30% lower losses than 2016 levels. Fluid choice drives fire and environmental posture: mineral oil versus FR3 natural ester with a 360 C fire point and ready biodegradability. Legacy units require PCB screening, with clean units documented below 2 ppm.
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.
Procurement channels
Direct contract with Hyosung HICO for new units, with the Memphis plant serving US-standard orders; the company publishes no unit pricing. Used EHV supply is brokered dealer inventory, and the only observed example in August 2026 was a HICO 500 kV class 134/179/224 MVA shell-type unit at Transformer Exchange, contact for pricing. At this scale the class is universally quote-driven, which is a structural feature of the EHV market rather than a gap in one brand's supply.
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.