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Oil Level Leak Inspection
Transformer oil level and leak control: conservator gauge, gasket-flange seal scan and level-drop root cause analysis with signed reports.
Oil level leak inspection verifies that the insulation and cooling oil in oil-filled transformers stays at the right level — reading the conservator gauge and scanning the body-flange-adaptor-bushing lines and the cooling circuit for seepage — and investigates the cause when a level drop is found. A critically low level creates two simultaneous hazards: windings exposed to air lose cooling and absorb moisture degrading insulation, and the empty space above the oil carries explosion energy. Catching the leak early is therefore both an equipment and a safety question.
Inspection Items
- Level verification: Readability of the glass gauge, level against the temperature scale, and on units with automatic level monitoring (LSO) relay alarm-trip contact tests; comparison of drop speed with historical records.
- Leak scan: Search for oil traces and dust build-up at cover gaskets, flanges, bungs, radiator joints, pump-adaptor seals and under bushings — a leak traps dust lint and marks its route visibly.
- Conservator and breather: Membrane-bladder integrity, breather silica gel saturation-moisture state (pink-chalk colour marks saturation); air ingress matters additionally because it accelerates oil oxidation.
- Structural root cause: Separation of level loss due to leakage versus consumption (evaporation-overheating-gas release); under crack or bad-weld suspicion, below-oil leak observation and pressurised verification where needed.
- Environment and fire: Oil tray and drainage line clogging, fire-spread and soil-water pollution aspects of escaped oil; sealing repair and cleaning procedure audit.
Interpretation and Intervention
A level drop alone is not a leak: temperature swing changes oil volume, membrane conservators can hide seepage silently, and a blocked relief can mislead the reading. The control therefore runs three steps: level-temperature correlation chart, leak point marking (fluorescent dye with UV detection), and where available oil volume record comparison. The identified leak is removed by gasket change (de-energised maintenance plan) or immediate isolation per its criticality. On a unit at the critical level threshold, operation is restricted at once — winding exposure above oil is a non-returnable threshold accelerating temperature and insulation failure.
Legislation and Outcome
The control ties to the operating periodic examination duty under Law No. 6331 and the Regulation on High Current Electrical Installations; the environmental side joins waste oil and pollution legislation. Observations, automatic monitoring logs if any, and intervention proposals connect to the signed report. Oil system controls sit in our Transformer Tests and Analyses group; for integrated programmes combining Thermometer Examination and General Cleaning services, contact us.
FAQ on Oil Level and Leak Control
The level gives the first clue about leaks, overheating-expansion or internal fault-pressurization. A falling level indicates a gasket-pipe-valve-bushing leak or a breather problem; losing oil exposes the insulation and grows the breakdown-outage risk, while hot oil reaching the surface is a burn-environment risk. That is why temperature-compensated level sights (conservator glass) are read regularly and trended.
Gasket joints at body-bushings, the conservator-tank-relay pipe line, valve-plug-purge connections, radiator-cooler pipe-weld zones, the tap changer cover and flanges are scanned visually for dampness-oil film-paint blistering-darkening, and thermal camera (thermal control) separates hot from leak. Seepage can also appear as slow drip-crystallisation; the floor drainage trace is a clue. If the level falls with no leak found, internal fault-gassing is investigated.
In conservator-type transformers the tank breathes with outside air as the oil expands-contracts; if the moisture in that air is not held by a silica-gel dehumidiser (breather) — when the gel is saturated or its colour turned — it enters and oil moisture-acidity rise. Therefore gel state-quantity-connection-tightness is checked and contaminated gel is changed in planned maintenance. A blocked breather pipe disturbs the positive-negative pressure balance and produces leakage-pumping.
A fast level drop, an active dripping-open leak, oil running from a hot surface or the level under the critical mark is urgent: the load is reduced and the transformer can be taken out of service in a planned way, because exposed insulation grows the breakdown-burst risk. After locating the leak, gasket-pipe change-refill-vacuum treatment is done and verified with leak-vibration-expansion tests. The report carries the level trend, leak location and removal suggestion.