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Oil Immersed Transformer - Oil Cooling System

Oil immersed transformer, also called oil filled transformer, is a kind of voltage transformation device utilizing oil cooling method to reduce the transformer temperature. Different from the dry type transformer, the body of oil immersed transformer is installed in the welded steel oil tank filled with insulation oil. When oil immersed transformer in operation, the heat of coil and iron core firstly is transformed to the insulation oil and then to the cooling medium. And according to the capacity sizes, it can be divided into immersed natural cooling transformer and immersed forced air cooling transformer.

An oil-immersed power transformer with green shell.
Oil-immersed power transformer.An oil-immersed power transformer is installed in a power distribution system.
Oil-immersed power transformer relies on insulation oil as the cooling medium.
S9, S10 series 10 kV three phase off-load tap changer distribution transformer
Type    Rating (kVA)    On-load loss (w)    Load loss (w)    No-load current (%)    UK (%)    Dimension (mm)    Weight (kg)
a    b    c
S9-M-50/11    50    170    870    2.0    4.0    1215    660    1170    430
S9-M-250/11    250    560    3050    1.2    4.0    1190    815    1370    1115
S9-M-400/11    400    800    4300    1.0    4.0    1515    770    1580    1380
S9-M-500/11    500    960    5050    1.0    4.0    1635    840    1610    1600
S9-M-1000/11    1000    1700    10300    0.7    4.5    1960    1095    1960    2860
S9-M-2500/11    2500    3300    23000    0.55    5.5    2230    2305    2445    5660
S10-M-30/10    30    110    600    1.8    4.0    870    645    1025    310
S10-M-50/10    50    140    870    1.7    4.0    1090    650    1080    395
S10-M-80/10    80    200    1250    1.6    4.0    1140    675    1110    490
S10-M-100/10    100    240    1500    1.5    4.0    1185    690    1130    560
S10-M-125/10    125    280    1800    1.4    4.0    1205    710    1180    670
S10-M-160/10    160    340    2200    1.3    4.0    1255    720    1200    780
S10-M-200/10    200    400    2600    1.2    4.0    1295    740    1215    875
S10-M-250/10    250    470    3050    1.1    4.0    1340    755    1260    1115
S10-M-315/10    315    560    3650    1.0    4.0    1400    770    1320    1280
S10-M-400/10    400    680    4300    0.9    4.0    1500    860    1400    1490
S10-M-500/10    500    810    5150    0.9    4.0    1575    895    1430    1740
S10-M-630/10    630    1020    6200    0.8    4.5    1660    930    1545    2110
S10-M-800/10    800    1190    7500    0.7    4.5    1830    1070    1590    2625
S10-M-1000/10    1000    1450    10300    0.6    4.5    1935    1175    1685    2860
S10-M-1250/10    1250    1650    12000    0.6    4.5    1960    1170    1730    3330
S10-M-1600/10    1600    2040    14500    0.5    4.5    2325    1220    2120    3765
S10-M-2000/10    2000    2140    17820    0.5    4.5    2395    1260    2225    4530
S11 series 20 kV three phase off-load tap changer distribution transformer
Type    No load loss (W)    Load loss (W)    No-load current (%)    UK (%)    Dimensions (mm)    Weight (kg)
a    b    c    d    e    f
S11-M-30/20    100    690/660    2.1    5.5    1100    700    1240    14    400    400    640
S11-M-50/20    130    1010/960    2.0    1130    710    1260    14    400    450    710
S11-M-63/20    150    1200/1150    1.9    1160    740    1270    14    400    450    780
S11-M-80/20    180    1440/1370    1.8    1200    770    1280    14    400    450    860
S11-M-100/20    200    1730/1650    1.6    1220    800    1300    14    400    450    900
S11-M-125/20    240    2080/1980    1.5    1270    840    1330    19    550    450    970
S11-M-160/20    290    2540/2420    1.4    1320    870    1350    19    550    550    1100
S11-M-200/20    340    3000/2860    1.3    1360    900    1380    19    550    550    1240
S11-M-250/20    400    3520/3350    1.2    1430    910    1430    19    550    650    1420
S11-M-315/20    480    4210/4010    1.1    1460    920    1450    19    550    650    1570
S11-M-400/20    570    4970/4730    1.0    1490    940    1470    19    660    750    1740
S11-M-500/20    680    5940/5660    1.0    1570    970    1540    19    660    750    1950
S11-M-630/20    810    6820    0.9    6.0    1650    1000    1580    19    660    850    2290
S11-M-800/20    980    8250    0.8    1750    1070    1650    19    820    850    2690
S11-M-1000/20    1150    11330    0.7    1830    1170    1690    19    820    850    2880
S11-M-1250/20    1380    13200    0.7    1900    1200    1790    19    820    850    3400
S11-M-1600/20    1660    15950    0.6    1950    1250    1850    19    820    900    4100
Voltage ration (kV): 20(10) ± 5%/0.4. Connection: Yyn0, Dyn11.
Matters need to attention: 
Due to the oil immersed transformer is immersed in the oil tank, if the oil spray or leakage, there may result in fire. Thus, oil immersed transformer is generally used in separate room or exterior places. If the climate of the installation region is relatively heat and humidity, the oil immersed transformer is also a good choice.

Fire precaution: 
We should pay specially attention to the fire precaution of the oil filled transformer.

The fireproof distance between oil filled transformer with oil over than 2500 kg and oil-filled electric equipment with 600-2500 kg oil should not less than 5 m.
When fireproof distance of two adjacent oil filled transformers does not meet requirements, the fireproof wall or fireproof water curtain on top of the fireproof wall should be set. When it comes to single-phase oil filled transformer, it only needs to set fireproof wall or fireproof water curtain.
When the distance between outside building wall and oil filled transformer in outside is less than the standard regulations, the outside building wall should adopts the fireproof wall and the distance between wall and voltage transformer should not less than 0.8 m.
When the oil filled transformer or other oil-filled electric equipment with oil over than 1000 kg, oil storage pit and oil collection basin should be set, at the same time, the transformer cobblestone should be stored for fireproof or oil offloading.
According to the relevant present provisions, oil filled transformer should be equipped with fire extinguishing system. Oil filled transformer used for factory should be set in a separate room. The room door should be the class B fire door and open to the outside or corridor and it should not open to other rooms.