|
Reference
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R-core Transformer
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Toroid Transformer
|
EI Transformer
|
| Shape |
The Standard model is thin, small &
light |
Small transformer leads to higher copper
loss. |
The Ideal shape is square. The transformer
tends to be large & heavy. |
Leakage
flux |
With balanced winding canceling the leakage flux, the total amount of leakage flux is extremely small.
As a result can be used even without shield. |
Winding is not balanced hence there is
lot of leakage flux. To reduce the effect there is a need to provide shielding. |
There are gaps in the magnetic path and the winding is not balanced. As a result the leakage flux is very high which can affect sensitive electronic components if proper shielding is not provided. |
| Winding |
Winding is done on special machine resulting in evenly spaced winding. Balanced winding is an inherent constituent of the design. |
The winding is not evenly spaced. The density of turns on the inner edge is more and on the outer edge the wires are roughly spaced out. Thus the winding is not balanced. |
While the layers of turns are well laid out the winding is only on the center limb of the EI core. Thus it is not balanced. |
Exciting
Current |
The exciting current is minimal as all the magnetic paths are in alignment with the rolling direction of the steel and there is no
gap in the core. |
The exciting current is less than that in EI Transformer, but the same is higher than that of R-core transformer due to lack of balancing of winding. |
More exciting current is required due to presence of magnetic gaps,the inability to use the effect of rolling direction of grain orientedsteel, the variation in assembly operation, etc. |
| Insulation |
Double structure bobbins are used ensuring complete separation between primary & secondary winding. Thus safety standards are easily met. The dielectric strength is more than adequate. |
The winding is done on the core without the use of bobbin. Thus difficulties are observed in meeting safety standards. |
Partition bobbins allow separation between Primary and Secondary bobbins but this is not complete. The dielectric strength is not as good as R-core. Difficulties are observed in meeting safety standards. |
| Efficiency |
Very low losses result in better efficiency. Efficiency of greater than 90% is generally observed in most designs. |
Efficiency is better than EI Transformer but less compared to R-core transformer. |
More losses result in poor efficiency. |
| Heat |
Heat generation is minimal due to low Iron loss. The large surface area of the coil allows for better heat dissipation. |
The core is not exposed at any point. Thus the heat generated has no area for dissipation. Thus temperature rise is more. |
Due to iron loss the heat generation is more. Further as large part of the winding is covered inside the core there is poor heat
dissipation. |
| Mounting |
Due to thin design & light weight can be accommodated in available space of assembly. Can also be mounted vertically on the sides. |
Because of circular shape the length & width of the space should be identical. |
Usual cubic space takes more space in assembly |
