35kV-220kV Oil-Immersed Vertical Current Transformers from China Suppliers and Factory for Protection and Measurement

The current transformer has a wound iron core. According to the accurate class requirement, the material thereof is cold-rolled oriented silicon steel sheet or soft magnetic material with high permeability.

The secondary winding is wound from high quality electromagnetic copper wires and the insulation and heat resistance class is B. It is wound on the iron core uniformly. The iron core is wrapped in a high-quality insulating material to ensure sufficient insulation between the secondary wires and iron core.

The insulation between the primary winding and the grounding part is made by wrapping with high-voltage cable paper, which is dried and oil-immersed under a high vacuum state to ensure strictly the requirements of local discharge quantity and dielectric dissipation factor tan δ. The products at a voltage level of 66kV and below is in a chain structure, with the main insulation being wrapped and wound on the primary winding wire cores by using high-voltage able paper tape to ensure a sufficient dielectric strength; the product at a voltage level of 110kV and above has the main insulation in a capacitance screen voltage-sharing structure to increase the lightning impact endurance voltage level. At the same time, the distribution of the operating voltage is optimized.

The external insulation is made of high-strength ceramics with a brown surface. Besides, a surface in other colors can also be provided if necessary. The creepage distance is selected according to the pollution in the surrounding environment or the need of customers.

The oil storage tank of the transformer is made of cast aluminum alloy or diamagnetic steel plate. In the internal part, the primary winding wire core connects with the primary wire conducting terminal. On the upper part of the oil storage tank, a metal expander is installed.

The oil tank of the transformer is welded from steel plates. After treatment to remove dirt and rust, the surface is sprayed with RAL7011 finish after being subject to surface plastic spray treatment. Other colors may also be provided according to relevant requirement. On the oil tank, secondary terminal box, grounding bolt and nameplate are provided. There is also a lifting lug for product hoisting. In the bottom, four mounting holes are provided for securing the transformer onto the mounting base.

The primary terminals are made of aluminum alloy or tin-plated electrolytic copper according to the level of primary current. The secondary terminals and end shield grounding terminals are installed in the terminal box, which are made of copper.

In the transformer, quality transformer oil is injected, which is dehydrated, degassed under a high vacuum state to ensure the micro-water content therein to be lower than 10×10-6 g per gram. The electric performance of the insulating oil can be ensured.

The transformer is required to be fully-enclosed and no transformer oil is allowed to get in contact with air. The high-quality corrugated metal plates made of stainless steel are used to compensate any change resulting from oil volume varying with temperature. As a result, it is ensured that no contact occurs between the oil and air. This isolation is a kind of effective protection.