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does anyone know about insulation system?

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tvp2598

New Member
dear all,

does anyone know about insulation system and winding structure for power transformer?

i want to know about them and some figures that show how it should be built or how does it look like.

thank you in advance,

regards,

tvp2598
 

pike

Member
hey good to see an aussie on the forums-like me :p

I think you mean induction, not insulation. Induction is measured in henry's. The higher the induction the higher the amount of recoil when pulsed with ac current. The faster the AC, the more current you can transform with a smaller tranformer.

A transformer is basically 2 coils of wire on a good inductor such a ferrite or iron. The ratio in turns on each coils is the voltage stepup/stepdown ratio.

I know that house hold power is rated at 50-60 hertz, but why can't we jack that up to something like 500 Hz -60 so we can have smaller household transformers??? (like 10 times smaller)
 

Phasor

Member
I think you mean induction, not insulation.
No, it is quite possible that tvp means what he/she says. Perhaps they can clarify it.

Most transmission and distribution transformers are oil-insulated, and the oil is also used as a cooling medium (either by natural convection, or by being pumped through a radiator) though for high voltages (> 132kV), SF6 gas insulation is an increasingly viable option. SF6 (sulphur hexafluoride) is great stuff - its insulation resistance is about 5 times that of air, so you can put 132kV busbars 5cm apart from eachother 8) It's non-toxic and colourless, heavier than air. The downside is that it requires expert installation, therefore initial costs are quite high, and when you get an arc in it, it forms a fine white powder which is poisonous.

I know that house hold power is rated at 50-60 hertz, but why can't we jack that up to something like 500 Hz -60 so we can have smaller household transformers??? (like 10 times smaller)
This would cause big problems for AC motors. In order to maintain the shaft speeds, which we get at 50Hz (750, 1500, 3000 rpm), the motors would have to incorporate 10 times as many poles - eg, a 4 pole motor for 50Hz, would need 40 poles at 500Hz. So they would be much bulkier and more expensive. Also, the impedance of transmission lines would be increased at higher frequency (they are not just resistive, they have inductive and capacitive components too...).
 

tvp2598

New Member
insulation

dear all,

i mean insulation that used in transformer which has 3-phase

thanks in advance for any opinions.

regards,

tvp2598 (i'm male)
 

stevez

Active Member
You might consider contacting manufacturers. I was pleasantly suprized when I contacted a capacitor manufacturer and asked for some information. They certainly won't give away secrets but they may be willing to help out. Even if all they do is send you literature that describes their products it may be enough.
 

Symon

New Member
Not sure if you still want to know about this, considering the age of this thread. But most transformer windings are insulated with a kind of varnish, or resin that is coated on the windings before they are wound. Once the windings are finished they usually are immersed in a big tank filled with varnish which is then subjected to negative pressue in order to draw out any air that might be trapped between the windings. Low-cellulose paper may also be used to seperate the different layers of windings.

In a step-down transformer than has a high current secondary, the windings may be spaced apart with blocks of densified wood soaked in varnish (since the 'windings' now look more like solid bars more than wire).

Like has been said before, the most common insulation medium in medium to low voltage transformers is mineral oil (commonly Shell Diala-B in Australia), since it is a good insulation medium, and is also good for cooling.

SF6 is an excellent insulating medium, however it has terrible cooling properties, so it is mostly used in switchgear and busbar systems, rarely in transformers.
 
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