H‑Infinity

Testing is the final verification that a transformer meets its design specifications and is ready for reliable service. Factory tests confirm manufacturing quality, while site tests verify correct installation. Together, they form a comprehensive quality gate — if a transformer passes all tests, it has proven it can perform its electrical, thermal, and mechanical duty for decades. Skipping or shortening tests is a false economy that can cost millions in repairs or replacements.

01What Do We Test?

Transformer testing covers both factory (FAT) and site (SAT) tests:

▸Winding Resistance — Measure DC resistance of all windings to verify correct tap connections, conductor sizing, and joint quality. Compare phase-to-phase balance.
▸Turns Ratio — Verify turns ratio of all windings and tap positions to confirm correct winding configuration and tap changer operation.
▸Insulation Resistance — Megger testing of windings to ground and between windings at multiple voltage levels (500 V, 1 kV, 5 kV, 10 kV) to verify insulation integrity.
▸Dielectric Withstand — Power frequency and impulse withstand voltage tests to verify insulation can handle normal and transient overvoltages.
▸No-Load & Load Loss — Measure core losses and winding losses at rated conditions to verify efficiency meets specification.
▸Impulse Testing — Standard lightning impulse and switching impulse tests for transformers above 72.5 kV.

02Why Testing Matters

Testing catches defects before they become failures:

▸Manufacturing Defects — Poor solder joints, incorrect tap connections, and winding displacement are caught during factory tests before the transformer leaves the factory.
▸Installation Errors — Bus bar connection errors, bushing damage, and oil contamination during handling are detected during site tests.
▸Baseline for Future Diagnostics — Test results from initial commissioning form the baseline for trend analysis throughout the transformer's life.
▸Insurance & Warranty — Test certificates are required for insurance and warranty validation. Without them, claims may be denied.

03Our Approach

We follow a systematic testing approach from FAT through SAT:

1. Factory Acceptance Test (FAT)

Witness routine tests at the manufacturer's works — winding resistance, ratio, insulation, and dielectric tests. Review type test certificates for impulse and short-circuit withstand.

2. Site Acceptance Test (SAT)

Post-installation testing after oil filling, settling, and hot circulation. Verify insulation resistance, winding resistance, ratio, and dielectric tests.

3. Special Tests

Partial discharge measurement, noise level measurement, temperature rise verification, and sweep frequency response analysis (SFRA) for post-fault diagnosis.

4. Report & Documentation

Comprehensive test reports with raw data, comparison to specifications, and recommendations. All results stored as baseline for future diagnostics.

04Scope of Testing & Commissioning

Our testing services include:

▸FAT Witness — On-site factory witness testing at manufacturer's facility with detailed test reports.
▸SAT Execution — Complete site acceptance testing using calibrated portable test equipment (Megger, Omnistep, HiTest).
▸SFRA Testing — Sweep Frequency Response Analysis for winding displacement detection — a sensitive diagnostic for post-transport and post-fault condition assessment.
▸Combined Testing — Integration of transformer testing with substation commissioning including relay coordination and protection testing.

05Standards & Compliance

✓IEC 60076-1 to -11 — Transformer Testing

✓IEEE C57.12.90 — Standard Routine Tests

✓IEEE C57.149 — SFRA Interpretation

✓ASTM D877 / D1816 — Dielectric Strength

06Why H-Infinity

Our testing team brings portable, calibrated test equipment and years of field experience. We've witnessed factory tests for over 500 transformers and conducted site acceptance tests for 300+ units across the GCC. We don't just run tests — we interpret results, identify anomalies, and provide clear recommendations. Our reports are thorough enough for utility-grade documentation and our SFRA capabilities provide advanced diagnostic insight into winding condition.

Test & Commissioning