Transformers fail quietly, then all at once. Condition-based testing identifies moisture, insulation, and mechanical issues early, allowing you to plan repairs instead of incurring downtime. ABM delivers on-site, NETA-aligned testing with NFPA 70B-guided maintenance practices and IEEE C57 references, plus clear deliverables your insurers and auditors can follow.¹

Who this is for and when it matters

• Sites with medium- or high-voltage distribution, like data centers, hospitals, airports, manufacturing, campuses, and utilities
• Triggers that warrant testing: commissioning and retrofit, post-fault or nuisance trips, abnormal IR scans, rising gas alarms, seasonal outages, and end-of-warranty reviews

Safety

Before any test, we verify switching orders, lockout/tagout procedures, grounding, energized work boundaries, arc-flash labels, access and cribbing arrangements, and single-line drawings. Test ports, clearances, and communications are confirmed with operations so work proceeds safely and predictably.

Quick checklist you can start today

• Nameplate and single line, last test reports, oil history (DGA, furan, moisture)
• Relay settings and OLTC maintenance logs
• Calibrated test sets for TTR, winding resistance, power factor (tan δ), insulation resistance and PI, SFRA
• Oil sampling kits and chain of custody, IR camera, ultrasound, partial discharge instrumentation (where scope allows)

Core tests and why each matters

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Maintenance actions that pair with testing

• Oil processing: vacuum dehydration and degasification, inhibitor checks, and top-ups
• OLTC service: inspection, cleaning, adjustment, contact wear remediation, gasket replacement
• Bushing work: cleaning, torque/retorque, gasket replacement, planned swap-outs
• Mechanical and electrical: lead re-termination, tightening, tap mechanism service, fan and pump checks
• Protection and controls: relay calibration, functional trip checks, verification of points, alarms, and logging with your BMS/SCADA/EPMS

Commissioning and acceptance done right

We review factory docs, inspect for shipping damage, then establish a clean baseline: TTR, winding resistance, insulation, power factor (tan δ), SFRA, ratio, and tap checks. Protection is verified end-to-end (CT polarity and burden, relay settings, schemes, and functional trips), so the first energization is boring in the best possible way.

Condition-based versus time-based programs

Time-based programs are simple, but they don’t reflect actual risk. ABM sets a baseline, then right-sizes cadence by criticality, load, operating environment, and trend direction.

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Common findings and how we respond

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Data you should always capture and keep

Temperature-corrected PF and PI, DGA indices, moisture ppm and BDV, TTR by tap, winding resistance, OLTC timing, SFRA curves, IR images, torque logs, corrective actions, and next-test due dates. Year-over-year trending is your best early-warning system.²

What ABM delivers

Testing is only useful when it’s repeatable, documented, and followed by fixes. ABM structures the work so results hold up to review.

• Test plans aligned to NETA ATS/MTS and IEEE C57 guidance, with NFPA 70B-informed maintenance steps³
• On-site testing with calibrated instruments for energized surveys and de-energized diagnostics
• Clear pass or fix cues with priority codes and scheduled corrective work
• A consolidated report that includes raw data, temperature-corrected trends, interpretations, and recommendations ready for auditors, insurers, and operations

Measuring success

• Fewer unplanned transformer-related outages and nuisance trips
• Stabilized or improved DGA, moisture, and power factor trends
• On-time PM and corrective close rates, improved MTBF and MTTR
• Smooth insurer and compliance reviews with complete documentation

Talk with a transformer testing specialist

Let’s put a clear plan around transformer health and make it repeatable, documented, and inspection-ready. We’ll review your assets and recent test history, align on risk and downtime windows, then scope a condition-based program that fits your site. From oil/DGA and power factor to TTR, SFRA, and OLTC checks (as needed), we’ll schedule the right tests, run them with calibrated gear, and turn results into prioritized work orders your team can execute. Get in touch.

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Sources:

¹ Insight: Transformer Monitoring and Testing

² Individual Temperature Correction for Insulation Resistance Measurements

³ Demystifying NFPA 70B and NETA MTS: Which Guide Aligns with Your Electrical Maintenance Needs?