Cast resin transformers ambient air temperature

[stratford]

On site we have two cast resin transformers 2MVA running at loads between 50-60% of nominal rating. The air temperature during summer period exceeds the value of 40 oC and sometimes reached 45 oC. The transformers are cooled with natural circulation of air from air holes on the bottom and air holes at the outlet of the room door. Can i suggest the instalaltion of air inakte fan with filter? According to IEC 76-2 the ambient air temperature should not exceed 40 oC.

 

[DanDel]

The critical issue is the winding temperature of the transformer. The transformer should have a temp gauge to tell you what this is. The nameplate will give you a maximum temp rise above ambient (I believe typical ambient in this case is 25°C).

Any increase in air flow in the room will help, just make sure there is a place for proper exhaust if you have forced intake.