Oil Immersed Hermetically Sealed Transformers

General Features

The hermetically sealed oil transformers are normally manufactured with a sealed tank equipped with fins that allow the expansion at the temperature variations. The tightness of the tank is up to 0.5 Bar. This type of transformer is the most widely used in the world. In the hermetically sealed transformer, the oil does not come into contact with the air and its electrical properties are therefore not compromised, ensuring a long life span of the transformer. For powers exceeding 3150kVA, or in case of a transformer with radiators, the transformer can still be hermetically sealed by means of a nitrogen cushion.

For this type of transformers the expansion of the insulating liquid is compensated by the elastic deformation of the oil-cooling radiators attached to the tank. The protection against internal faults is ensured by means of a DGPT device: Detection of Gas, Internal Over Pressure and Oil Over Temperature.

Standard Feaures
  • HV bushings according to DIN 42531 or EN 50180
  • LV bushings according to DIN 42530 or EN 50386
  • Off-Circuit tap changer in 5 positions
  • Tank made of corrugated walls
  • Thermometer pocket
  • Contact thermometer (for transformers ≥ 630 kVA)
  • Safety valve
  • Lifting lugs
  • Rating plate
  • Earthing terminals
  • Filling plug & Drain cock
  • Bi-Directional rollers – 90°
Standard Accessories
  • Earthing Terminals
  • Low Voltage Bushings
  • Off Load Tap Changer
  • Safety Valve
  • Terminal Box
  • Filling Tap
  • Conservator (if not hermetic)
  • Buchholz Relay
  • Lifting Lugs
  • Thermometer pocket
  • Medium Voltage Windings
  • Bi-Directional Rollers
  • Magnetic Core
  • Oil discharge and extraction valve
  • Low Voltage Windings
  • Clamps
  • Oil level indicator (if not hermetic)
  • Medium Voltage Bushings
  • Silica Gel Breather (if not hermetic)
  • Tank with Corrugated Wall
  • Plug-in connectors (upon request)
  • Earthing point on tank
  • Name plate
  • Jacking Pods
Accessories Upon Request
  • DGPT2 or RIS or DMCR (if hermetic)
  • LV Extension Bars
  • Safety Valve with Contacts
  • Winding Temprerature Indicator
  • Cable Box (MV / LV)
  • Oil Level Indicator with Contacts (if not hermetic)
  • PT100 sensors for oil temperature control (PTO)
  • Others (Contact Us)