G&G Renewable Services provides specialized field engineering services for power transformers and substation equipment across the United States from new-unit assembly and commissioning to advanced diagnostics, component replacement, and emergency repair. Working with major equipment manufacturers and their engineering partners, our team completed 30+ field engagements in 2024-2026 for utility, hyperscale data center, solar/renewable, and industrial clients across California, Arizona, Illinois, Wisconsin, Georgia, Michigan, and Texas.
Power Transformer Assembly & Commissioning
Scope performed at each site:
External visual inspection of the transformer (coating condition, oxidation, bushing protection boxes, grounding)
Verification of the accessory checklist and transformer hermeticity (pressure and preservation system check)
Supervision of mechanical assembly per manufacturer procedures
Oversight of all technical acceptance tests prior to energization
Full documentation package and client sign-off on completion
Our technical team has provided on-site supervision and commissioning support for the assembly of multiple power transformers (25-40 MVA class) at utility substations in California, working to Siemens Energy's SATMA assembly and testing standards (SATMA 101.01 / 101.02 / 101.03).
Nine substation transformer assemblies completed to date, 25-40 MVA class, California.
Substation transformer assembly — California
Substation transformer assembly — California
Substation transformer assembly — California
Substation transformer assembly — California
Substation transformer assembly — California
Substation transformer assembly — California
Substation transformer assembly — California
Substation transformer assembly — California
Substation transformer assembly — California
Beyond new-unit commissioning, G&G Renewable Services provides rapid-response and scheduled field repair for in-service transformers nitrogen/oil leak correction, control cabinet replacement, current transformer (CT) exchange, busbar repair, coating restoration, and thermometer/temperature-control replacement. Fifteen after-sales engagements completed in 2025 alone, for utility and hyperscale data center clients.
Municipal utility client, California: nitrogen leak repair across multiple in-service transformer units
Hyperscale data center operator, Midwest & Southeast U.S. (Wisconsin, Illinois, Georgia): transformer oil change; control cabinet repair and replacement; coating/paint restoration; current transformer (CT) replacement across several units; low-voltage busbar repair; insulating base repair; oil leak correction
Independent power producer, Texas: winding-temperature control (INCON) repair and thermometer replacement on a large power transformer
Industrial equipment client, California: nitrogen leak repair on a large power transformer
Industrial client, California: oil leak repair and thermometer replacement
Typical repair methodology (example: oil/nitrogen leak correction)
Full lockout/tagout (LOTO) and de-energization before work begins
General inspection and leak-source identification
Nitrogen injection (5-6 psi) to displace moisture during the repair
Leak correction using PTFE tape / liquid PTFE sealant, or component replacement as needed
Oil drain, treatment, and refill where required
Post-repair dielectric strength test (>50 kV) and hermeticity check (6 psi nitrogen hold, 4 hours)
Transformer normalization and return to service
Advanced Transformer Servicing -- Bushings, Cable Work, Oil Systems & Tap Changers
High-voltage lead extension and bushing-compatibility assessment on an in-service utility transformer, including oil sampling and dissolved-gas/dielectric testing (California)
Internal high-voltage cable extension and full oil re-fill with post-service electrical testing (California)
Internal transformer inspection under confined-space entry to diagnose abnormal operating sound, including borescope and visual assessment of the active part (California)
Low-voltage bushing replacement on a utility-scale solar power plant transformer, performed to Siemens SAT-MA service instructions (Arizona)
On-load tap changer (OLTC) inspection, condition assessment, and replacement analysis on ABB equipment.
For higher-complexity interventions on Siemens and ABB equipment, our team performs internal transformer work requiring de-energization, oil handling, and -- where needed -- confined-space entry. Recent engagements include:
For select engagements, G&G Renewable Services works alongside a specialized U.S. field-service partner to extend nationwide coverage and technical capacity. Joint engagements completed in 2025-2026 include:
High-voltage bushing replacement following surface damage (cracking) -- Arizona
On-site structural welding correction -- Arizona
Medium-voltage bushing replacement with full oil-handling and electrical test sequence -- California
Low-voltage bushing replacement and oil-leak correction, including leak detection, winding-resistance testing, and pressure testing -- California
Bushing bolt-torque and clearance sampling inspection across a transformer fleet, following a bushing-failure rootcause investigation -- Michigan
Dissolved-gas-driven insulating oil reprocessing via vacuum treatment and recirculation -- multiple U.S. sites
Protective fuse replacement (bayonet and backup) following a protection-device operation -- multiple U.S. sites
PT100 temperature-sensor inspection, troubleshooting, and replacement -- multiple U.S. sites
Root-cause analysis and load-break switch (LBS) replacement -- multiple U.S. sites
Unusual-noise investigation with a full electrical test suite (insulation resistance, transformer turns ratio, winding resistance) -- multiple U.S. sites.
Powering Reliability Across the Energy Transition
CONTACT INFO:
Phone: +1 561 221 5857
Email: gguruceaga@ggrenewableservices.com
Address: 2400 Augusta Dr #141, Houston, TX 77057
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