EN
Transformer Inspection
Periodic inspection of power transformers: oil and leak control, thermography, cooling groups, bushing tests and protection device examination. Signed reports.
Transformer periodic inspection audits at least annually the dry-type and oil-filled power transformers converting voltage in facilities: external examination, tightness and level control, cooling and ventilation organs, connection and insulator integrity, thermographic scanning and protection device operability. Detailed electrical tests and oil analyses (DGA, dielectric) run separately under our Tests and Analyses scope; this page's control is the periodic surveillance layer of operating safety.
Inspection Items
- Body and oil system: Corrosion under tank paint, sealing points (lid gasket, bungs, radiator joints), oil level gauge and conservator (membrane) status; accuracy of thermometer-gauge readings.
- Bushings and connections: Cracks-contamination on bushing surfaces (tracking marks), discolouration-loosening at primary-secondary busbar joints; torque verification.
- Cooling: Radiator core cleaning and clogging, fan motors and thermal start-up tests; oil pump circulation (per ON/OF/OF/FA groups).
- Protection gear: Buchholz relay contact examination and cable, sudden pressure relief device, pressure alarm indicators, thermal relay returns; verification of dialogue with MV cell.
- Thermography: Panel-bushing-cable head scan at full or near load; hotspot reference comparison (phase-to-phase delta-T).
- Earthing and structural: Body-earth continuity, neutral-earth link; foundation and seismic support, vibration, oil tray-drainage status.
Legislation and Standards
Periodic examination, maintenance and testing of distribution transformers foresee at least annual control plus special tests under the Regulation on High Current Electrical Installations, the Earthing Regulation and TEDAŞ/distribution company specifications. The technical reference is the TS EN 60076 series (power transformers); for oil types, oil tray and leakage control is part of environmental legislation. Results are entered into the operation file and used for the notification duties of the grid operator.
Risks and Operator Recommendations
The most common field findings are a loosened bushing connection as hot spot (first caught by thermography), cooling capacity loss through dust-lint on radiator cores and water damage on Buchholz cabling. In heavy-load years thermography frequency should double; hotspot trend must become the basis of planned shutdown maintenance decisions. For dry types, fan-filter cleaning and insulation resistance tracking in humid periods; for oil types, attention to leaks as soil-ground contamination. Surge arrester status indicators must be read at every control.
Outcome
At the end of the examination a signed report with thermogram, measurements and non-compliance table is issued. Transformer controls are within our Periodic Inspection of Installations group. For measurement and laboratory test sets see our Transformer Tests and Analyses page, or contact us for your programme.
FAQ on Transformer Inspection
Electrical tests: winding resistance, turns ratio (TTR), vector group, insulation resistance-polarisation index and tan delta (capacitance-loss), short-circuit impedance-losses (type-acceptance), no-load current-loss; for oil types breakdown voltage, moisture, acidity (TAN), DGA (dissolved gas analysis), furans (paper polymerisation) and visual particle-colour control; for dry types insulation-temperature monitoring. All measurements follow the IEC/TS EN 60076 test set.
On-site periodic control runs at most yearly in operating practice (half-year for critical transformers), with manufacturer-design life tracking thresholds; oil-DGA analysis follows a trend (annual routine plus extra after a fault). Legal basis: Law No. 6331 and the Work Equipment Regulation, the High Current Installations Regulation (MV facility operating-certificate duties), distributor acceptance conditions, and fire safety and earthing (earthing control) requirements.
Rising H2-CH4-C2H2-C2H4 ratios in DGA (Rogers-Duval classification separating partial discharge, overheating and arcing), growing moisture-acidity and falling breakdown (insulation degradation-contamination), rising tan delta, low winding resistance or step imbalance (moisture-interturn short), tap changer position mismatch, oil level-leak and thermal camera (thermal scan) findings of overheated connections; these signs trigger planned maintenance instead of a fault loss.
A transformer fault produces a production stop, fuel-energy loss, equipment-fire risk and supply-security violation. Periodic test-trend delivers the maintenance-repair-replacement decision on time with a planned budget (oil change-drying, tap cleaning, gaskets-bushings, cooling fan-pump); insurance-expertise needs are met and the operating documents (report, approval, period) are complete. The report stays in the OHS-energy file as a reference document with value tables, trend curves and interpretation-suggestion.