Electric Power Systems
Rapeseed Oil-Immersed Transformers (ULTrans)
ULTrans, Kitashiba’s new environmentally friendly distribution transformer uses a natural ester vegetable oil (rapeseed oil) as an insulating oil. The use of rapeseed oil improves environmental performance, prevents soil contamination, and improves safety. Additionally, the rapeseed oil-immersed ULTrans transformer provides long life and low loss. ULTrans also reduces the on-site installation period since it is transportable while fully assembled.
The new distribution transformer can be customized to suit individual requirements in terms of capacity, voltage, frequency, wiring and so on. For details, contact Kitashiba.
Feature of ULTrans
Long life (60 years)
The high moisture absorption property of rapeseed oil helps reduce the amount of water absorbed into the winding insulation paper and thus prolongs the life expectancy of the transformer from 30 years to 60 years.
The residual strength (average degree of polymerization) of the coil insulating paper determines the lifespan of the transformer.
Differences in degradation between different types of insulating paper
Degradation of insulating oil (coloration)
Reduction in power loss (by approx. 15%)
Through fluid analyses of the internal states of transformers, we improved the cooling performance of rapeseed oil. As a result, the internal power loss of transformers has been reduced significantly.
ULTrans exhibits much lower load losses than the conventional transformers.
Comparison of Power Loss
Fully assembled transportation for the reduction of the on-site installation period (roughly three days at the shortest)
Consequently, the on-site installation period can be reduced from nine days to roughly three days.(* In the case of a 20,000kVA transformer)
The size of ULTrans has been reduced by changing the shape of radiators.
The installation period is reduced because ULTrans is transportable while fully assembled.
Rapeseed oil used in the new environmentally friendly transformer (ULTrans), which has a fire point of 300°C or higher, provides enhanced safety.
Sample oil is put into a long cup and ignited with a gas burner, and changes caused by burning are observed.Mineral oil starts burning in a few seconds while rapeseed oil is not set aflame after 60 seconds.
Considerations for reducing environmental loads
Reduction in CO2 emissions
The amount of carbon dioxide emissions generated by the disposal of rapeseed oil is equivalent to the amount of carbon dioxide absorbed while rapeseed plant grows. This means that using rapeseed oil helps mitigate global warming.
The rapeseed plant used for Kitashiba’s transformers is a carbon-neutral material that emits very little carbon dioxide throughout its life cycle, including during growth, and the refinement and incineration of oil.
Prevention of soil contamination
The biodegradation percent of rapeseed oil is 89%, as opposed to 17% for mineral oil. The use of rapeseed oil helps prevent environmental pollution.
Biodegradability of rapeseed oil
Decomposition by bacteria
Ratings & specifications
|Capacity||Up to 200MVA or so|
|Cooling method||Oil-immersed self-cooling, oil-immersed air-forced cooling, oil-directed air-forced cooling|
|Frequency||50Hz or 60Hz|
|Voltage||Up to 187kV or so|
|Phase displacement||Yy0 or Yd1|
|Oil deterioration prevention||Main unit: Non-pressure sealing (OH-D), LTC: Non-pressure sealing (OH-D)|