Generator Step-Up (GSU) Transformers for Sale

Large-project transformer and substation procurement

For hyperscale data centers, utilities and EPC teams, J&J reviews high-MVA and high-kV transformer requirements with phased quantities and current equipment records. Include downstream padmounts and dry types from 500 kVA upward, medium-voltage switchgear and breaker schedules when you need a coordinated electrical equipment quote. Large power-transformer delivery is confirmed against the actual unit and release scope.

• Hyperscale data-center substations and high-MVA transformers
• Bulk padmount, dry-type, switchgear and breaker supply

Buying several transformers or reviewing an exact ratio?

For a multi-unit order, specify each electrical configuration, accepted condition and delivery phase. Start with the current equipment records, then request the identity, documents, allocation and quote scope for each proposed unit.

• Multi-unit power, GSU and substation transformer orders
• 138/13.8 kV transformer buying
• 69/34.5 kV transformer buying
• 230/69 kV autotransformer buying

Find a GSU for your generator or collector project

J&J Transformers LLC sells generator step-up and collector transformer equipment for U.S. power plants, EPCs, IPPs and renewable projects. Start with your generator or collector-bus voltage, grid voltage and required continuous MVA. Compare the equipment records below, then request the unit's price, available documents and delivery scope.

• For an existing plant, send the transformer nameplate and the replacement or spare requirement.
• For a new project, send the one-line or voltage and MVA schedule, quantity and required arrival date.
• Identify step-up, collector or proposed step-down operation so the offered winding arrangement and duty can be reviewed correctly.

• 138/34.5 kV transformer records
• 230/34.5 kV transformer records
• 345/34.5 kV transformer records
• Generator, GSU and circuit-breaker matching

New, used and surplus GSU transformers for sale

Generator step-up transformers for sale cover generation-terminal and collector-bus duties with different winding requirements. Compare the actual high and low sides, cooling-stage MVA, grounding and insulation. Used GSU records retain service-history and reconditioning details; unused equipment and future production are identified separately.

• Pre-owned and reconditioned GSU offers
• Compare GSU manufacturers and records

GSU transformers for sale by grid voltage

Compare power transformers for sale for 69 kV, 115 kV, 138 kV, 230 kV, 345 kV and 500 kV system projects. Review each equipment record's exact winding voltages, MVA, condition and current allocation before requesting a quote.

• 69 kV transformers for sale
• 115 kV transformers for sale
• 138 kV transformers for sale
• 230 kV transformers for sale
• 345 kV transformers for sale
• 500 kV transformers for sale

Review the offer, condition and release basis

Current records separate J&J-confirmed availability, dated written offers, newly submitted inventory schedules and 2027 production positions. Stored surplus is not automatically used equipment, and future production is not ready-to-ship stock. Request current allocation, photos, matching records, inspection and complete loading, shipping and warranty terms through J&J.

• Documented used and rebuilt transformer offers
• Search all transformer listings
• Purchase and delivery options

Can a turbine or generator package use one of these GSUs?

First compare the generator's actual terminal voltage and frequency with the transformer's low-side winding and rated frequency. Then reconcile MVA, power factor, impedance and its base, grounding, phase displacement, insulation levels, tap range and fault duty. A 13.8 kV generator is not a direct match to a 34.5 kV low-side winding merely because both packages have similar MW ratings.

• Generator, GSU and circuit-breaker matching checklist
• Megawatt generators and fleet options
• Gas turbine packages for sale
• Generator and substation circuit breakers

Who supplies GSU transformers for generation and data-center projects?

J&J Transformers LLC buys, sells, and supplies large GSU transformers for IPPs, utilities, EPCs, renewable projects, and data-center onsite generation. Published opportunities include five brand-new, never-used Kolektor ETRA 66/88/110 MVA, 138/34.5 kV units. Match generator-side and grid-side windings to the one-line; MVA alone does not establish compatibility. Contact Tommy Marco at 346-276-9540 or tommy@jjtransformers.com with MVA or MW, voltages, quantity, site, and need-by date. Current availability requires written reconfirmation; subject to prior sale. Final allocation and delivery terms are confirmed in writing.

• 300 MVA 138/34.5 kV Georgia Transformer
• 220 MVA 345/34.5 kV Prolec GE Transformer
• 180 MVA 345/34.5 kV Georgia Transformer
• 120 MVA 138/34.5 kV Georgia Solar GSU
• Five 110 MVA 138/34.5 kV Kolektor ETRA GSUs
• New 220 MVA 230/34.5 kV ABB/Hitachi Transformer
• 167 MVA 230/34.5 kV Fortune Electric Transformer
• 88 MVA 230/34.5 kV WEG Power Transformer
• 71.2 MVA Prolec GE 240/120-13.8 kV GSU
• ILJIN 167 MVA 230/34.5 kV New / Unused Transformer
• WEG 120 MVA 230/34.5 kV Transformer Offer
• 42 MVA 138/34.5 kV Virginia Transformer
• 260 MVA 345/34.5 kV Siemens Transformer
• 208 MVA 138/34.5 kV Stored Surplus Transformer
• 208 MVA 138/34.5 kV Transformer — 2027
• ABB 133 MVA 115/13.2 kV Pre-Owned GSU
• 65 MVA 138/13.8 kV Reconditioned GSU
• 12 TSEA 226 MVA 345/34.5 kV Transformers
• 7 TSEA 266 MVA 345/34.5 kV Transformers
• 21 TSEA 116 MVA 138/34.5 kV Transformers

Buy a large GSU transformer

Review the listed generator step-up and collector-transformer opportunities below, or contact J&J with a replacement or new-project requirement. The generator or collector voltage, export voltage, MVA and duty determine which units warrant a closer review.

• Identify the generator or collector duty, MVA and required voltage on each winding.
• Tell Tommy your quantity and required date, including whether this is a replacement or a new project.
• Discuss the actual unit's winding connection, cooling ratings, tap changing, condition and available records directly.

• Five Kolektor ETRA 110 MVA-class, 138/34.5 kV GSUs
• Georgia Transformer 180 MVA-class, 345/34.5 kV power transformer
• Prolec GE 71.2 MVA, 240/120 to 13.8 kV GSU
• Substation transformers for sale and supply
• Bulk pad-mounted transformer orders
• 138/34.5 kV Transformers
• 230/34.5 kV Transformers
• 345/34.5 kV Transformers

What makes a transformer a replacement candidate?

A matching voltage ratio is the starting point. Compare the existing transformer and proposed replacement on the same rating basis before reserving equipment. Send the nameplate or one-line by email when available; an initial conversation can begin with MVA, voltages and your required date.

• How to compare transformer nameplates
• Review condition and available records

What GSU transformer specifications must be confirmed?

A useful GSU quote needs the generator and system interfaces, not only a target MVA and high-side voltage. Submit the generator rating, terminal voltage, frequency, power factor or reactive range, neutral arrangement, high-side system, BIL, impedance target and basis, cooling, taps, losses, site conditions, tests, accessories, and required date.

Which GSU voltage ratios fit gas turbines, engines and renewable projects?

There is no universal GSU ratio for a technology. Generator terminal voltages vary, and the high side must match the plant bus or interconnection. Ratios such as generator voltage to 69, 115, 138, 230, or 345 kV are plausible examples only; the nameplate, one-line, and studies control selection.

For a simple-cycle or combined-cycle plant, confirm whether the electrical generator is included with the turbine, its terminal voltage and MVA, the generator circuit breaker arrangement, auxiliary supply strategy, and expected operating cycles. A turbine-only opportunity is not a generating package.

For reciprocating-engine or modular-generator plants, confirm the unit grouping and collector voltage. Multiple low-voltage or medium-voltage units may feed a collector system before one or more GSUs; the redundancy and protection architecture affects the transformer count and rating.

For converter-heavy renewable or storage duty, supply the harmonic-current spectrum, converter controls, expected operating envelope, grounding, and point-of-common-coupling requirements. Do not assume a conventional rotating-generator GSU can be applied unchanged.

Does IEEE C57.116 certify a GSU transformer?

No. IEEE C57.116-2022 is an application guide for unit power and unit auxiliary transformers directly connected to generators or connected through generator switching equipment. It is not a product certification. Product requirements, tests, purchaser specifications, and OEM evidence must be stated separately.

GSU review may also reference current IEEE C57.12.00 general requirements and IEEE C57.12.90 test methods where applicable, or specified IEC 60076 parts. The exact editions and contractual hierarchy belong in the purchase specification.

Requested tests may include routine electrical tests, losses, impedance, dielectric tests, impulse where specified, temperature rise, sound, SFRA, oil/fluid tests, and witness FAT. A generic test list does not prove a serial number has passed those tests; obtain the certified report or agreed new test plan.

Applicable standards, listings, tests, and efficiency requirements are confirmed for each quoted unit; naming a standard is not a certification claim.

How long does a GSU transformer take to procure in 2026?

J&J does not publish one universal GSU lead time. A defensible schedule identifies whether the option is an existing unit, unfinished factory slot, custom order, or used asset; then states engineering, approval, material, test, ex-works, transport, and delivered milestones with the quote date and dependencies.

An existing unit can still require ownership confirmation, technical comparison, condition inspection, testing, missing accessories, preservation, dismantlement, heavy-haul planning, permits, oil handling, and site work. “In stock” is not the same as ready to energize.

Availability is subject to prior sale, technical review, and written confirmation by J&J Transformers LLC.

What documents and commercial terms should accompany a GSU quote?

Procurement should receive a serial- or model-specific technical and commercial packet. The offer should identify the OEM, model/serial, manufacture year, condition, location, ownership authority, included equipment, drawings, tests, losses, impedance basis, fluid, dimensions/weights, shipping state, inspection/FAT options, availability, price, Incoterm, warranty provider, payment terms, exclusions, and validity.

• Technical: nameplate, rating sheet, outline, schematics, bushing/terminal data, accessory list, test report and losses.
• Condition: operating/storage history, inspection evidence, maintenance, DGA/moisture and electrical tests when used, preservation and transport history.
• Scope: transformer, oil/fluid, coolers, fans/pumps, conservator, controls, monitoring, arresters, neutral equipment, spares and loose-shipped parts.
• Logistics: origin, dimensions/weights, shipping split, oil state, route assumptions, truck/rail/vessel, permits, unloading and final delivery point.
• Commercial: seller identity/authority, currency, price, taxes/tariffs, Incoterm, schedule dependencies, warranty, payment, inspection rights, reservation and expiration.

What should I submit for a turbine and GSU package RFQ?

Submit the turbine and electrical-generator data separately, plus the desired power-system interfaces. If the electrical generator is not included with a turbine, say so. J&J needs model, gross/net output basis, terminal voltage, MVA/PF/reactive data, fuel, frequency, ambient/altitude, operating mode, package scope, interconnection voltage, auxiliary plan, site, schedule, condition preference, and available documents.

Transformer sales completed by J&J

Review original photos and confirmed equipment details from J&J's completed transformer sales. These historical units have sold; current requirements are reviewed against the equipment offered today.

• Two 100 MVA Waukesha transformers — completed sale
• 75 MVA Prolec transformer — completed sale
• 30 MVA GE transformer — completed sale
• Federal Pacific 46/12.47 kV transformer — completed sale

Use the buyer tools before comparing equipment

Estimate the load, review the candidate's condition records, and compare the complete quotation on the same basis. These resources help your project team identify missing information before accepting a transformer offer.

• MW to MVA and three-phase current calculator
• Seven transformer condition questions
• Worked example of total transformer purchase cost

GSU MVA, cooling duty and impedance data for project review

Match generator or collector duty to the actual winding ratings and operating direction. Request each cooling-stage MVA and the applicable impedance test data with its reference base. Keep generator output, transformer capacity and switchgear fault requirements as separate documented inputs to the project review.

• GSU cooling-stage and operating-direction checks
• Impedance data to request with a GSU offer

Buying a replacement or planning a spare?

Compare the offered transformer with the operating unit and the project specification. Keep the winding duty, cooling-stage ratings, technical deviations, inspection scope and delivery responsibilities beside the quoted price.

• Spare and replacement transformer compatibility checklist
• Transformer shipping and site delivery checklist

Review a proposed step-down operating direction

Some units can be considered for step-down service, but suitability depends on the actual winding arrangement, permitted operating direction and MVA, cooling, grounding, taps, impedance, insulation, protection and project interfaces. Request the unit's nameplate, drawings, test records and any manufacturer restrictions before accepting a candidate.

The Royal SMIT 525/69 kV record lists 240/320/400 MVA cooling stages and a separate 250 MVA maximum for step-down duty. The 400 MVA step-up rating is not a 400 MVA step-down rating. Its 13.7 kV buried-delta tertiary is not presented as an accessible external load supply.

• Can a GSU transformer be used for step-down service?
• Step-down transformers for sale and project requirements

Generator step-up transformer quotation inputs

A GSU transformer for sale must match the generator-side voltage, grid-side voltage and generator duty. Include generator MW and power factor, continuous MVA, cooling stages and interconnection requirements. A listing's maximum cooling rating does not establish the permitted rating in another operating direction.

• Compare the generator nameplate, transformer winding connections and grounding with the approved one-line; specify startup, station-service or proposed reverse power flow separately.
• Request a defined quote for the transformer, accessories, testing records, generator circuit breaker and delivery scope rather than assuming a complete generating package.

• Estimate generator-side and grid-side current
• Match the generator, GSU and breaker
• Review proposed reverse duty

Common questions

Written quotes and supporting records control unit-specific ratings, availability, condition, price, and delivery.

Related equipment and guides

Browse the related equipment and guides, or email Tommy to discuss your project.