Politubes produces for transformer industry a wide range of tubes used for insulation and protection of tie rods:

• For oil transformers we supply spiral tubing using a creped kraft paper that provides a larger impregnation surface area;
• For Dry Cast resin transformers we supply spiral tubing made of Mylar®, Nomex® or crepe Nomex® (with superior impregnation properties) for transformers that reach high temperatures.

In all types of transformer it is important to insulate electrically the tie rods that keep the packs of laminated steel compressed, so that induced electric currents are not generated in the tie rods themselves.

These currents can be induced by electric flows produced by some windings that do not complete the flow chaining with the other windings and this means that some electromagnetic fluxes can then be closed through the air. If they reach the tie rods, crossing them and generating a difference of potential this can cause some serious dangers to the transformers.

Politubes insulating tubes are used to avoid this problem on transformers tie rods, guarantee the correct insulation and avoiding this kind of danger.

Compared with tubes produced through simple coiling, spiral tubes provide the following advantages:

1. Telescoping effect during insertion is avoided;
2. They are custom designed and produced with the required length reducing possible waste and operator time;
3. They are supplied with a constant tube thickness around the entire circumference. They are engineered without overlap, ensuring better uniformity and insulation balancing.

They are supplied with high wall thickness (between 0.3 and 3 mm) to ensure perfect insulation and guarantee mechanical rigidity.