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Transformer conservator, explosion vent and breather

Short answer

Conservator tank accommodates oil expansion/contraction, keeps main tank full and minimizes oil-air contact. Explosion vent releases sudden pressure during internal faults to prevent tank rupture. Breather contains silica gel that dries air entering conservator, and an oil cup traps dust, maintaining oil dielectric strength.

Explain the function following parts of a power transformer. i) Conservator tank ii) Explosion vent iii) Breather

i) Conservator tank

A small cylindrical tank mounted above the main tank and connected to it by a pipe (with the Buchholz relay in between).

  • Oil expands and contracts with load and temperature; the conservator takes up this change, so the main tank always stays completely full of oil.
  • Only the small oil surface in the conservator touches air, which reduces oxidation and moisture absorption.
  • Its oil level indicator shows the oil level.

ii) Explosion vent

A bent pipe on top of the main tank, closed by a thin diaphragm (bakelite/glass), or a modern spring-loaded pressure relief valve.

  • During a severe internal fault, arcing decomposes oil into gas and pressure rises suddenly.
  • The diaphragm bursts and releases the pressure, preventing the tank from bursting or exploding.

iii) Breather

A small container filled with silica gel, with an oil seal cup, fitted on the conservator air pipe.

  • When the oil contracts, air is drawn into the conservator through the breather.
  • Silica gel absorbs moisture (blue colour turns pink when saturated); the oil cup traps dust.
  • This keeps the oil dry and maintains its dielectric strength.

✓ Answer checked by Claude Opus 5.5 (high effort)

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