Insulation Material For Oil Filled Transformers

Aug 11, 2016
Insulation Material For Oil Filled Transformers


In July 2015, a new higher efficiency standard took effect in the European Union and in year 2021 a second more stringent standard will take effect. The new standard of US DOE has taken effect since 1 Jan 2016, which published in April 2013. Though “more-stringent efficiency standards would be technologically feasible and economically justified”, potential issues mightly caused by these regulations.

For example, transformers will have to increase the size and weight in order to meet higher efficiency requirements. Bigger size of mounting poles as according to the US DOE, is needed, as well as bigger size of pads.

High-temperature insulation can help to mitigate these issues and even bring additional benefits to transformer manufacturers and end users.

Conventional liquid-filled transformer insulation

Since the transformers were deployed, liquid filled transformers have been using conventional insulation materials. Presspaper, also known as kraft paper is made wood based. It's thermal class was 105 °C and many years ago thermally upgraded kraft paper is developed to withstands 120°C. They are applied between conductor layers in a coil and between the conductors to ground.

 Kraft paper, which is wood based paper, electrically insulates areas between conductor layers in a coil and between the conductors to ground. Originally, the thermal class was and a few decades ago the industry introduced thermally upgraded Kraft paper which withstands an additional 15 . 

Mineral oil as a cooling system and also insulation system will soke into the paper. In order to cool the interior conductors, it has to be good cooling channels for the winding. Then epoxy resin diamond dotted paper is introduced to the electrical grid. 

The certain gap between each resin dot ensures the elimination of air content in the corona and partial discharge.

Haotai provides the best quality DDP in China and is competitive with Weidmann material.