Electrical tests

Diagnostic electrical testing for transformers and substations

Each test isolates a different failure mode. We run them with Omicron and Megger instrumentation, correct for temperature and deliver a protocol compared against standards and asset history.

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Transformer turns ratio test (TTR)

Verifies the turns ratio between high- and low-voltage windings to detect shorted turns, tap-changer faults and connection errors.

Insulation power factor and Tan Delta

Measurement of dielectric losses in transformer and bushing insulation to detect moisture, contamination and paper-oil ageing before they cause failure.

Insulation resistance and polarization index

Measurement of insulation resistance with a megohmmeter and calculation of absorption and polarization indices to assess moisture and cleanliness of the dielectric system.

Dissolved gas analysis in oil (DGA)

Chromatography of the insulating oil to detect incipient faults — arcing, partial discharge and hot spots — from the gases dissolved in the oil, without de-energizing the transformer.

Sweep frequency response analysis (SFRA)

SFRA test that detects mechanical deformation and displacement of windings and core — invisible to conventional electrical tests — after short circuits, transport or earthquakes.

Transformer winding resistance test

Measurement of the DC resistance of windings to detect loose connections, broken strands and bad tap-changer contacts.

Transformer excitation current test

Measurement of the no-load current the transformer draws to detect shorted turns, core defects and tap-changer faults.

Physicochemical oil analysis

Battery of physical and chemical tests on transformer oil to assess its condition and decide reconditioning, regeneration or replacement.

Moisture in oil (Karl Fischer)

Measurement of water content in transformer oil by Karl Fischer titration — moisture is one of the main accelerators of insulation ageing.

Furan analysis (paper ageing)

Measurement of furanic compounds in oil to estimate the ageing of the solid insulation (paper) — the part of a transformer that cannot be renewed.

PCB (askarel) content in oil

Testing transformer oil for polychlorinated biphenyls (PCB / askarel) — a regulatory and environmental compliance requirement before servicing or disposal.

Ground (earthing) system measurement

Measurement of the resistance and integrity of a substation grounding system to ensure personnel safety and correct protection operation.

SF6 circuit breaker testing

Testing of SF6 high-voltage circuit breakers: gas quality, contact resistance, timing and mechanism, to ensure reliable interruption.

Talk to a transformer specialist

Tell us about your asset and we'll respond with a diagnosis and a tailored quote — not generic pricing.

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