LikangCao@vanenergy.org +1 (323) 451-1707
Vanguard Energy Group LLC

Field service and repair

On-site inspection, repair and testing for power transformers, pad-mounted transformers, substations and inverters. Every job closes with a written field service report.

Power transformer repair

Inspection, testing and on-site repair of oil-immersed main and step-up transformers.

  • Oil leak and weld repair, gasket and bushing replacement
  • Electrical testing: TTR, winding resistance, insulation resistance
  • Insulating oil sampling, filtration and top-up
  • Tap changer, gauge and protection device checks

Pad-mounted and substation service

Fleet inspections and corrective maintenance for pad-mounted transformers and compact substations.

  • Fleet leak and pressure surveys, unit by unit
  • Nitrogen re-pressurization and pressure verification
  • Loadbreak switch, Bay-O-Net and bushing replacement
  • Repairs documented with photos for every unit

Inverter and PCS repair

Fault diagnosis and repair of central and string inverters and power conversion systems.

  • Fault code diagnosis and root-cause analysis
  • Power module, board and fan replacement
  • Firmware updates and parameter checks
  • Re-commissioning and performance verification

Energy storage system service

Service for battery energy storage sites, from the battery enclosures to the MV step-up.

  • Enclosure, cooling and fire-system inspection
  • BMS alarm and fault investigation
  • MV transformer and switchgear maintenance
  • Pre-acceptance and annual inspections

How a service job runs

The same five steps on every site, whether it is one transformer or a fleet of seventy.

  1. Request and scope

    Tell us the equipment, the fault or the inspection you need. We agree a scope, crew and schedule.

  2. Site inspection

    Every unit in scope is checked and photographed. Findings are logged against its serial number.

  3. Corrective action

    Repairs follow written procedures, with permits, lockout/tagout and spill control in place.

  4. Verification

    Pressure, leak and electrical tests confirm the repair before the unit returns to service.

  5. Field service report

    You receive a report with findings, actions, photos, test results and preventive recommendations.

Recent work: pad-mounted transformer fleet, energy storage site

Scope
Leak and pressure inspection of every pad-mounted transformer on site
Units inspected
77
Units repaired
3
Time on site
2 days, 2-person crew
Outcome
No further leakage at the follow-up check the next day
FindingAction takenStatus
Oil filling port, low gas pressurePort re-tightened, sealant applied, re-pressurized, leak testedResolved
LV riser weld and HV bushing areaOil cleaned, weld repaired, dye penetrant inspection, body pressure-testedResolved
Gas filling portOil traces cleaned, connection re-sealed, tank re-pressurizedResolved

Typical defects found and repaired

Oil seepage at the base of an LV riser weld
Seepage at an LV riser weld, repaired by hot welding
Pressure gauge and oil thermostat after re-pressurization
Pressure restored and verified after repair
Gas filling port flange after cleaning and re-sealing
Gas filling port cleaned and re-sealed

Standards we work to

  • IEEE C57 transformer inspection and testing
  • OSHA lockout/tagout and site safety
  • AWS D1.1 structural welding
  • ASTM D3487 insulating oil quality
  • EPA SPCC spill prevention and disposal

In every field service report

  • Scope, site, serial numbers and crew
  • Unit-by-unit inspection log with photos
  • Root cause, corrective action and status for each defect
  • Verification test results
  • Preventive recommendations

Book an inspection or repair

Tell us the equipment make and model, what you are seeing and where the site is. We reply within one business day with a scope and schedule.

Request field service

We reply within one business day. Your details are used only to answer this inquiry.