11KV Transformer Oil Change

[Ahr35181]

Can anyone advise on current recommendations with regards new oil settling time in an existing 1MVA 11KV/415V Transformer?

i.e. How long does the new oil need to settle before the transformer is tested &
re-energised?

Links to appropriate web sites would be appreciated.

Thanks,

Alan

 

[khodges]

Settling time is partially dependant on volume ... but I assume this unit to be around 2-5,000L of oil, so a settling time of 24 hours would be sufficient.

I would be wary of anything under 12 hours, as this does not allow sufficient time for oil to penetrate the kraftpaper insulation.

What oil filling process are you using? Hot oil fill? Placing the unit under vacuum? These will make a difference to the effectiveness of the oil to insulation medium penetration.